Equine MOD Flashcards
When you passport a horse what else must you do?
Microchip it
Does a foal need a passport if it’s being sold before it’s 6 months old?
No but the new owner has 30 days to get one
When does a foal under 6 months need a passport?
Export without its mum or sent for slaughter
Where is a microchip inserted?
Nuchal ligament, left hand side of neck
By when must a horse have a passport?
By the time its 6 months old or by 31st December of the year it’s born (whichever is latest)
How does the caudal maxillary sinus communicate with the frontal sinus? (horse)
Via the frontomaxillary sinus
Where do the rostral maxillary sinus and ventral conchal sinus drain?
Into middle meatus of nasal cavity via nasomaxillary aperture
Horses have a huge reservoir of RBCs where?
What causes RBCs to leave here and enter systemic circulation?
Spleen
At rest, 1/3 of RBCs are here
Exercise/stress -> adrenaline -> spleen contracts -> RBCs enter circulation. PCV can increase from 30-40% to 50-70% at maximum exercise
Where do the rostral and caudal maxillary sinus’ drain?
Middle meatus
Define a mare
A female horse 4 or more years old
What kind of breeder is a mare?
When is the breeding season?
A long day, seasonally polyoestrus breeder
(Most mares are in anoestrus over winter)
Increasing day length -> breeding season lasts from spring to late summer
A ‘transitional period’ of irregular cycling occurs at the start and end of the season
When does puberty occur in the mare?
Between 12 and 24 months
Cycling occurs for rest of life (although fertility may decline)
How long is the oestrus cycle in a horse?
How long does oestrus last?
When does dioestrus occur?
Cycle: 21 days
Oestrus: 4-6 days (ovulates in the last 25-48 hrs
Dioestrus: 16-17
Describe the oestrus cycle of a mare
Dioestrus: waves of follicles develop, reaching 25mm in size, then regress.
When hormonal conditions are correct, one follicle develops into a ‘dominant’ follicle -> produces oestrogens which induce oestrus
When it reaches >35mm -> ovulates
Oestrus ends within 24 hrs after ovulation
Ovulation site becomes corpus haemorrhagicum then corpus luteum (which produces progesterone)
The CL is refractory to effects of prostaglandins for 3-4 days after formation. After 15 days, endometrium releases prostaglandin -> luteolysis
What stimulates initial growth of follicles during dioestrus?
FSH
What stimulates oocyte and follicle maturation and ovulation during oestrus?
LH
What is the ‘transitional period’ during the reproductive cycle?
A period of change from anoestrus to regular cyclical activity
Lasts up to 6 weeks
Ovaries possess multiple small follicles 10-25mm diameter (‘bunch of grapes’)
Transitional follicles don’t ovulate and eventually regress
Mares show no sign of oestrus/behaviour
Mares mated now will not conceive (as there are no dominant follicles)
Eventually one follicle will develop properly and oestrus cycle will commence
Similar period happens when mares pass into anoestrus from oestrus (Autumn)
How can we manipulate oestrus using prostaglandins?
Induce luteolysis in CL
Oestrus will commence 3-5 days post injection
Side effects: transient colic, sweating, diarrhoea
How can we manipulate oestrus using progestagens?
Suppress oestrus
Withdrawal of treatment leads to rebound of ovarian activity; useful in shortening Spring transitional period
Intra-vaginal devices (PRID) sometimes used off-license
How can we manipulate oestrus using oestrogen?
Induce behavioural signs of oestrus (not true oestrus)
Only useful for maintaining ‘teaser mares’ for AI collection
How can we manipulate oestrus using chorionic gonadotrophin (eCG)?
If given during oestrus, will induce the dominant follicle (>35mm) to ovulate within 24 hours
How can we manipulate oestrus using Deslorelin (GnRH analogue)?
Hormone implant given sub-cut when follicle >30mm - should induce ovulation within 48hrs
How can we use light to manipulate oestrus?
Breeding season can be brought forward by using artificial light over winter
16hrs of light and 8 hrs dark from 2-4 weeks before Winter solstice
Light intensity important-should be able to read newspaper in darkest part of stable
Mares start to ovulate 8-10 weeks later
When should you serve a mare and why?
24-48 hours prior to ovulation
Oestrus behaviour ceases within 24hrs of ovulation-no longer receptive to stallion
Unfertilised oocyte viable for only 12 hrs post-ovulation
Spermatozoa viable for up to 48 hrs once in mare, take hours to reach oviduct
Mares served after ovulation have very poor conception rates
How will a mare in oestrus look when being scanned?
Dominant follicle on one ovary
Uterine oedema
Soft oedematous cervix
Oestrus: scan again 24-48 hrs later
Not in oestrus: give prostaglandins and scan again 3-5 days later
What happens to the endometrium during oestrus?
Becomes increasingly oedematous
Oedema decreases in the 24 hrs before ovulation
How long after mating should you scan the mare?
What are you checking for?
12-48 hrs
Has she ovulated (if not-mate again)
Check only one ovulation (twins)
Check for fluid in uterine lumen-post mating endometritis and treat accordingly
How is bacterial entry to the womb prevented?
Vulval seal
Vestibular seal
Cervical competence
How does poor perineal conformation lead to bacterial entry to the womb?
Poor perineal conformation prevents vulval and vestibular seals forming -> bacteria enters womb -> pneumovagina -> urovagina -> cervicitis
Uterine contamination prevents implantation of conceptus
Describe a good perineal conformation
No more than 4cm of vulva above pelvic brim
No greater than 10 degree slope to the vulva
How can you treat perineal conformation problems?
Caslick’s vulvoplasty
Remove a very narrow strip of vulval mucosa and suture up vulval seal, leaving 3cm unopposed to allow for urination
Sutures must be removed 5-10 days prior to parturition to prevent tears
How would you treat a persistent CL?
Give prostaglandins
What effects do granulosa cell tumours have on mares?
How are they diagnosed?
What is the treatment?
Cause either nymphomania, stallion-like behaviour or persistent anoestrus
Diagnosed by scan and blood test for Anti-Mullerian hormone
Surgery
Does endometritis affect conception?
No, but affects implantation and the inflammatory prostaglandins released may hasten luteolysis
What are the 3 types of endometritis?
Chronic infectious metritis
Free fluid in lumen
Mating-induced endometritis
Describe chronic infectious endometritis
Often caused by contamination of repro tract due to poor perineal conformation
May be reduced uterine immune defences
Agents include: E.coli, Pseudominas, Klebsiella, Strep. zooepidemicus, occasionally yeast/fungi
Describe endometritis where there is free-fluid in the lumen
Occurs as a result of uterine oedema during oestrus
May be sterile initially but good culture medium for bacteria
Could be due to delayed uterine clearance by incompetent mares (underlying motility disorder?)
Describe mating-induced endometritis
Mating contaminates repro tract with flora on stallions penis
Semen is inflammatory in itself
Transient inflammation is normal after mating/foaling/vaginal exam
Should be cleared up within 12 hours
Persists in some mares (abnormal uterine defences) -> embryonic loss, possibly chronic endometritis
How could you investigate endometritis?
Scan, especially post-service (needs treating if persistent fluid or fluid >1-2cm in depth)
Uterine swab and smear (culture, cytology)
Endometrial biopsy (histopath)
How can you treat endometritis?
Uterine lavage (saline) Oxytocin (repeated doses every few hours) Intrauterine antibiotics
How can you prevent endometritis?
Use of AI to minimise contamination
Why when treating endometritis, must you carry out treatment before day 5 of pregnancy?
The fertilised conceptus stays in the oviducts until about day 5 of pregnancy, after this it will be in the uterus. Therefore treatment of the uterus after day 5 will risk jeopardising the pregnancy
Describe chronic degenerative endometrial disease (endometriosis)
Progressive degeneration of endometrium and its replacement by fibrotic tissue
Major cause of age-related infertility (esp Thoroughbreds)
Begins about 11-12 yrs
Pregnancy has a positive effect, and lessens progression
Diagnosis: Histopath on endometrial biopsy
No treatment
Why might a mare have cervical incompetence?
Congenital problems or from foaling injury
Uterine cysts look similar to pregnancies on a scan, how can you differentiate between them?
Re-scan the mare in 24-48 hrs; the cyst will remain static in size and shape whereas the cenceptus will grow and will be motile up to day 16
Do uterine cysts cause fertility problems?
Rarely, unless very large
How would you perform a pre-breeding disease clearance test?
Clitoral swab for contagious equine metritis, send off to lab
What is the gestation period of a horse?
340 days
Overdue foals seldom cause a problem
Prematurity -> neonatal disease
Where does fertilisation occur?
Ampulla of oviduct
Embryo remains here for 5 days then it enters the uterus
When does the embryo migrate around the uterus and why?
Between day 5 (enters uterus) and 15/16
Essential for maternal recognition of pregnancy and prevention of prostaglandin release by endometrium
When does the embryo position itself in the uterus and where?
Day 15-16, usually at the base of a horn
When does placental attachment begin during pregnancy?
What else happens then?
Day 36
Endometrial cup production and attachment
When does the foetus grow into the uterine body?
After 70-80 days
Found mostly in the body until 6-7 months, after which it is so large that it occupies part of the horn again
How is pregnancy maintained?
CL produces progesterone
When do endometrial cups start secreting eCG?
From day 35
They maintain pregnancy for the first 5 months
What does eCG (equine chorionic gonadotropin) do during pregnancy?
Maintains primary CL and encourages secondary CL formation
When do endometrial cups degenerate during pregnancy?
Around day 70, gone by day 150
How are the first 5 months of pregnancy maintained?
Endometrial cups secrete eCG -> maintains primary CL and encourages formation of secondary CL
After about day 200 of pregnancy, all CLs have degenerated, so how is pregnancy maintained?
Foetal-placental progesterone production (acts locally)
When do foetal gonads start producing oestrogens during pregnancy?
From day 60 onwards
Abortions must be carried out by when if the mare is to be mated again in the same breeding season?
Why?
Before day 35, as this is when endometrial cups develop. These remain even if the foal has died. The mare will not come into oestrus whilst the cups are present.
How can you diagnose equine pregnancy?
Failure of mare to return to oestrus Lab tests (serum, measure eCG from days 45-90, or oestrone sulphate from day 120 onwards) (urine-oestrone sulphate from day 150) Manual rectal exam (usually done at 6 weeks, can ballot foetus at day 120) Rectal ultrasound (can be done from about 10 days after mating, although embryonic death and twins can occur after this)
When during pregnancy are early embryonic death rates highest?
In first 14 days
From when can you only image parts of the foetus, not the whole thing? (scanning)
6 weeks
When are PD scans usually carried out? (3)
15-16 days post-mating
- check for pregnancy or return to oestrus
- check for twins (can reduce whilst embryos are motile and can be separated, and before endometrial cups have developed)
24-26 days post-mating
- heartbeat visible
- can still reduce twins before cups have established
6 weeks (optional) -reassess (embryonic death less likely)
On a rectal ultrasound, how big will the conceptus be at 14 days, 16 days, 20 days, 25 days and 65 days?
14 days= 1cm 16 days= 1.5cm 20 days= 2cm 25 days= 3cm 65 days= 10cm
From when can a trans-abdominal scan be performed?
6 months onwards
How do you classify foetal death during pregnancy?
From fertilisation to day 40: early embryonic death
Day 40-300: abortion
Day 300 onwards: stillbirth
Give some causes of failure of pregnancy
Early embryonic death Viral (EHV-equine herpes virus 1, EVA-equine viral arteritis) Bacterial Fungal Twins Maternal stress/illness Foetal abnormalities Umbilical torsion Idiopathic
Give some causes of early embryonic death
Congenital abnomalities
Breeding on foal heat
Uterine environment problems (fibrosis, endometritis)
How may you reduce the risk of equine herpes virus in pregnant mares?
Vaccinate at 5, 7 and 9 months of pregnancy
May reduce risk of disease but doesn’t give full immunity
How can you diagnose equine herpes virus in pregnant mares?
PCR of nasopharyngeal swabs for horses showing respiratory signs
PCR of aborted material
When does abortion from equine herpes virus 1 occur?
Late term (>5 months), 1-3 months post-infection
How does equine viral arteritis (EVA) affect stallions and mares?
Stallions: become persistent infected shedders
Mares: abort then recover
Notifiable
Vaccine available
Which bacteria usually cause bacterial abortion?
How do they cause abortion?
Strep species, E.coli, Staph species
Occasionally Salmonella, Leptosporosis
Causes: ascending infection from cervix, haematogenous spread, introduction of bacteria at breeding (from stallion’s penis)
Although fungal infection is a rare cause of abortion, which fungal species is usually the cause?
Aspergillus spp
Why does a twin pregnancy lead to failure of pregnancy?
Mares are not designed to carry more than 1 foal- placenta needs to contact up to 70% of available uterus for adequate nutrition of foetus
Twins compete with each other for attachment space (nutrition). Often one twin runs out of space and dies. The other twin eventually is deprived of space by the remnants of the dead twin and is aborted.
Which is more likely to result in one twin being born:
Both twins in same horn
Twins in opposite horns
Why?
Both twins in same horn, as one twin may die early on whilst it is still small.
If in opposite horns, twins are more likely to abort as they’ll both get to a reasonable size before competing with each other
What percentage of twin pregnancies results in 2 live foals?
2 live: 1%
Of twin pregnancies, what percentage results in a live foal?
63%
What are some signs of abortion?
Vaginal discharge
Running milk
Colic/foaling signs
May be no signs at all
How can you investigate abortion?
Send whole foal carcass and placenta to pathologist
If not possible:
Examine placenta and cord
External exam of foal: weight, crown-rump length
Internal exam
Sample chorion, thymus, liver, lung, spleen
Samples from mare rarely useful
How do you induce abortion before 3 months?
Prostaglandin infection, abortion will occur 5-8 days later
If endometrial cups present, mare will not return to oestrus this breeding season
How do you induce abortion after 3 months?
Repeated prostaglandin injections (twice daily between days 80-150 -> abortion 2-5 days later)
Dilation of cervix and uterine lavage
Trans-abdominal injection of potassium chloride into foetal heart?
Dislocation of foetal neck per rectum?
Considerable risk in attempting termination of pregnancies after 100 days
How do you induce foaling?
Inject 1-2ml oxytoxin every 15-20 mins until delivery starts (may only need 1 dose)
Mare must be close to foaling anyway
What are the risks with inducing foaling?
Uterine rupture
Dystocia
Foal immaturity (matures in last 1% of pregnancy)
Retained membranes
Avoid unless absolutely necessary
What kind of placenta does a horse have?
Diffuse, epithelio-chorial
Give some risk factors for neonatal disease
Mare: placentitis, placental insufficiency, maternal illness, early lactation, poor colostral production
Foal: prematurity, failure of passive transfer
Dystocia
Premature placental separation
How long does it take a newborn foal to adapt to the external environment?
How one does it take it to stand and suck?
24-48 hours
Usually stands within 1 hour, sucks within 2
What is the difference between prematurity and dysmaturity?
Prematurity: a foal born before 320 days gestation that displays immature physical characteristics
Dysmaturity: a full-term foal that displays immature physical characteristics
Give some characteristics of a premature/dysmature foal?
Low birth rate Short, silky hair coat Floppy ears Domed head Weakness, prolonged time to stand Flexor tendon laxity Incomplete ossification of tarsal and carpal bones Severe cases: multiplayer organ dysfunction (eg respiratory depression)
By when do foals have adult levels of IgG?
4 months old
When is the crossover between maternal and foal IgG?
8-9 weeks old
IgG= 400mg/dl
What is the half life of maternal IgG?
20-23 days
Declines by 1-2 months
How are colostral antibodies absorbed?
Specialist enterocytes absorb the IgG by pinocytosis
These cells have a lifespan of max 24 hours
Maximum absorption occurs within 8 hours of life
How much colostrum must a foal have?
1 litre of colostrum within first 6 hours of life
Give some predisposing factors for failure of passive transfer
Loss of colostrum via premature lactation (eg due to premature placental separation)
Inadequate colostrum (IgG/volume) production
Failure to ingest adequate volume of colostrum
Failure to absorb colostrum
When is the best time to test passive transfer?
How?
18-24 hours
ZST (zinc sulphate turbidity test)
ELISA
Colostrum specific gravity can be tested pre-suck
What value of IgG indicates normal transfer of maternal antibodies?
> 8g/l
How do you treat failure of passive transfer?
If >12-24 hours, give foal plasma (from mare or commercial)
What are the consequences of failure of passive transfer?
Immediate-septicaemia
Rotaviral infections, joint sepsis, respiratory disease (1-4 months old)
By when should a foal develop a suck reflex?
Within 20 minutes
What is the body temp of a horse?
36.5- 38.5 (don’t show very high temperatures unless very unwell)
What is the body temp of a foal?
37.2-38.9 degrees (reflects environmental temp)
What is the heart rate of a foal?
Birth: 40-80 bpm
First week: 60-190 bpm
What is the heart rate of a horse?
27-40 bpm
What is the resp rate of an adult horse?
12-16 brpm
What is the resp rate of a foal?
Newborn: 45-60 brpm (no nostril flaring or exaggerated rib movement)
7 days of age: 35-50 brpm
By when should a foal pass meconium?
Within 24 hours
By when should a foal first urinate?
Dilute and large volumes first passed by 6 hours (colts) or 10 hours (fillies)
What is the average weight of a newborn foal?
45-55kg
What is the average weight gain of a new born foal?
0.5-1.5 kg/day
How much of its mothers milk should a newborn foal consume a day?
20-28% bodyweight
Feed every 2 hours
What partial pressure of oxygen indicates cyanosis in foals?
PaO2
Give some signs of sepsis in the mucous membranes of a foal
Congestion, petechiae
Brick red mucous membranes
When doing a physical exam on a foal, where should you pay particular attention to?
Umbilicus
Joints
Mucous membranes
Auscultation
How can you identify sepsis in a foal?
Blood culture (3 days for results, changes in foal can happen within hours) Sepsis score (neutrophil numbers, fibrinogen concentration, blood glucose, clinical exam, history)
How can you identify umbilical infection in a foal?
Ultrasound-look at umbilical vessels
Enlarged umbilicus
Drainage of pus
Pain on palpation
How can you diagnose pneumonia in a foal?
Radiography, blood gas analysis
How can you diagnose osteomyelitis/arthritis in a foal?
Synovial fluid analysis, radiography
Give an NSAID suitable for septicaemic foals
Flunixin 0.5-1mg/kg bid
What is oliguria?
What could you give to a foal with oliguria?
Production of abnormally small amounts of urine
Diuretics if persistent (furosemide-loop or mannitol-osmotic)
How often should you feed a sick foal?
Every 2 hours
Which antibiotics can you use in foals?
Aminoglycosides (care in young foals- nephrotoxicity)
Penicillins and other beta-lactams
Ceftiofur (high doses eg 5mg/kg)
Cefquinome 1mg/kg
How can you provide respiratory support in a newborn foal?
Move it from lateral to sternal recumbency (improves resp function)
Intranasal oxygen
Mechanical ventilation
Drugs (bronchodilators- B2 agonists, central stimulants)
Describe a sick foal
Weak, depressed, lack of suck reflex
What is the most important differential in a sick foal?
Neonatal septicaemia
Risk factors: FPT, hygiene, stress, management, disease
Which common pathogens can cause septicaemia in foals?
E.coli, Actinobacillus, Salmonella spp, Proteus, Klebsiella (all gram negative)
Beta-haemolytic streptococcus, Staphyocloccus, clodtridia
How do organisms enter the foal to cause septicaemia?
Openings (umbilicus?)
Open gut
Inhalation
In utero (mare placentitis)
What are the clinical signs of foal septicaemia?
Foal is off suck and lethargic
Increase resp rate and effort
Acute severe lameness
Discharge or swelling of umbilicus
Congested, dark mucous membranes or severe petechial haemeorrhages
Hypopyon (pus in anterior chamber of eye)
Diarrhoea
Meningitis
Fever not consistent (shock= low temp, SARS= high temp)
What is SARS?
Severe acute respiratory syndrome
Describe the physiology of septic shock (SIRS- systemic inflammatory response syndrome)
Vasoactive inflammatory mediators -> vasodilation
Increased metabolic rate and oxygen consumption
CO initially increased (hyperdynamic phase)
Microvascular permeability -> volume maldistribution
Increased CO can no longer be maintained (hypodynamic phase)
What does septic shock result in in foals?
Multiple organ failure
CNS depression
Renal failure
Autonomic exhaustion and decompensation of circulation
Give some differential diagnoses for a foal with respiratory signs
Neonatal septicaemia Viral pneumonia Meconium aspiration Aspiration pneumonia Pneumothorax Respiratory distress syndrome Pulmonary hypertension Central respiratory depression
What is CID/SDID?
Failure to produce functional B and T lymphocytes
Autosomal recessive
Arab breeds
Normal at birth, disease begins at 1-2 months old
Lethal
How do you diagnose CID/SCID?
Clinical signs
Persistent lymphopenia
What is PAS?
Perinatal asphyxia syndrome
Describe PAS
Dummy foals
HIE (hypoxic ischaemic encephalopathy)
Ischaemia, oedema and reperfusion injury to brain, kidneys, intestines and other organs due to lack of oxygen
Caused by in utero hypoxia or interruption of oxygen supply during birth
May not be apparent until foal is 12-24 hours old
Central respiratory depression
Give the symptoms of mild, moderate and severe PAS
Mild: unable to attach to mare, poor suck reflex
Moderate: aimless wandering, abnormal phonation (‘barkers’), blind
Severe: seizures, coma
How can you control seizures in foals with PAS?
Diazepam, phenobarbital
What can be given to foal with PAS that have cerebral oedema?
DMSO (dimethyl-sulfoxide)
Has anti inflammatory properties, traps free radicals
Are ruptured bladders more common in male or female foals?
Male due to longer urethra
Describe the aetiology of a ruptured bladder in a foal?
Usually excessive pressure during parturition on a distended bladder
Congenital defect also possible, due to dorsal site where there is a change in the muscle of the bladder wall
Describe the presentation of a foal with a ruptured bladder
Signs normally present within first 2-3 days of life
Dysuria (painful urination) esp stranguria (frequent attempts to urinate with only small amounts passed)
Depression and abdominal distension after 2 days
How do you diagnose a ruptured bladder in a foal?
Post-renal azotaemia with hyponatraemia (low sodium), hypochloraemia (low chloride ions) and hyperkalaemia (high potassium)
Ultrasound (urine in abdomen)
May see calcium carbonate crystals in peritoneal fluid
Why do newborn foals have proteinuria?
Absorb small molecular weight proteins from colostrum
How do you manage a ruptured bladder in a foal?
Correct metabolic acidosis and electrolyte changes with IV fluids
Hyperkalaemia may induce arrythmias -> give 0.9% saline with 5% glucose
Resp distress, atelectasis etc should be corrected with oxygen therapy, ventilation and reducing abdominal fluid
Slowly drain peritoneal fluid prior to surgery (it removing urachus)
How does a foal with colic present?
Quiet, will lie down and curl up (like a croissant)
What are some differential diagnoses for a foal with colic?
Meconium impaction Ruptured bladder/uroperitoneum Overfeeding/ lactose intolerance Distension from diarrhoea Gastric ulcers SI/ LI obstruction Congenital abnormalities
Newborn foals have 30-40% higher what than an adult?
Creatinine
Describe neonatal isoerythrolysis
Aa and Qa negative mares mated to positive stallions
Foal inherits RBC antigens from stallion
Exposure of the mare to these antigens causes her to produce alloantibodies to the foals RBCs
At birth, the foal ingests later numbers of RBC antibodies in colostrum -> haemolytic anaemia
How can you diagnose neonatal isoerythrolysis?
Coombs test to detect antibodies on RBCS
How can you prevent neonatal isoerythrolysis?
Blood type both parents before mating
Can withhold colostrum or use jaundiced foal agglutination (JFA) test to detect antibodies against foal RBC’s
What is the treatment for neonatal isoerythrolysis?
Blood transfusion (if PCV 12-15% or less) Donors must be Qa or Aa negative, or washed mare RBCs Supportive care (antibiotics, anti-ulcer meds, monitor fluids, glucose, nursing)
Foal heat diarrhoea affects foals of what age?
Why does it occur?
How does it present?
5-12 days
Changes in bacterial flora in foal
Alteration in milk composition relating to hormonal changes in mare (oestrus)
Mild, self-limiting diarrhoea
No treatments, or can use probiotics or intestinal protectants
Describe clostridial diarrhoea
Severe peracute frequently fatal
Necrotising foul-smelling faeces
Seen in individual septicaemic foals and as outbreaks
Cl difficile and Cl perfringens most common (normal Gi inhabitants)
Severe gas distension and colic
Contagious-isolate
How do you diagnose clostridial diarrhoea in foals?
Culture- normal flora so interpretation difficult
ELISA or PCR (for toxins)
Gas in or on the mucosa in ultrasound
How do you treat clostridial diarrhoea?
Metronidazole, penicillin
Describe cryptosporidium infection in foals
No intermediate hosts Faeco-oral infection Attach to brush border Incubation 3-7 days Diagnosis: flotation of faecal Oocytes or direct FA Treatment: supportive therapy Prevention: good hygiene and management
Describe rotavirus infection in foals
1-4 weeks of age
Highly infectious (outbreaks)
Diarrhoea
Diagnosis: ELISA, electron microscopy
Treatment: passive immunisation, supportive therapy
Prevention: phenolic disinfectants,passive immunisation, vaccination of pregnant mares?
What causes equine strangles?
Streptococcus equi
Describe Rhodococcus equi
Excreted in dams faeces, builds up on pasture in warm, dry conditions, ingested, colonises WBCs, abscessation Enteric infection (persistent diarrhoea, fever) Intra-abdominal abscess (fever, colic)
What causes equine proliferative enteropathy (EPE)?
Lawsonia intracellularis
What are the effects of equine proliferative enteropathy (EPE)?
How old are affected foals?
How do they get it?
Weight loss, oedema, lethargy, depression, weakness, diarrhoea, mild colic
3-11 months of age
Infection from faeces (equine or other species)
How do you diagnose equine proliferative enteropathy (EPE)?
Ultrasound
Hypoproteinaemia
PCR of faeces and serology
How do you treat equine proliferative enteropathy (EPE)?
Antimicrobials eh erythromycin, rifampin, Oxytetracycline
Give some mechanisms for weight loss in a horse
Reduced intake: inappropriate feeding, competition for feed, dental disorders, dysphagia, unable to obtain feed
Reduced digestion or absorption of nutrients: dental disorders, malabsorption syndrome, liver disease
Increased losses: protein-losing enteropathy
Increased requirements: pregnancy, lactation, sepsis, neoplasia, other systemic disease
Give some common causes of weight loss
Dental disorders, parasitism, inadequate diet, PPID (Cushings disease), liver disease, malabsorption and protein-losing enteropathy, chronic diarrhoea, abdominal abscess, renal disease, cardiac disease. Chronic thoracic disease, non-GI neoplasia, equine grass sickness
Why are enzyme deficiencies not a problem in horses?
Bacteria in the hind-gut are able to adapt to increased substances eg lactose that would increase in the absence of enzymes
What% ofa horsesBWTshoulditbeeatinginbulk?
Between 2 and 2.5% BW in roughage
What is the difference between chronic and recurrent colic?
Chronic: colic signs of variable intensity lasting 48 hours or more
Recurrent: shorter period of colic pain which recur at variable intervals
What is ‘colic?’
Acute abdominal pain
Only a symptom
Most commonly related to GI tract
Give the causes of recurrent colic
Anything that pulls on the mesentery
Non-intestinal
Gastrointestinal: mesenteric traction, motility disorders, inflammatory, intermittent partial/complete obstruction
What % DM is hay, haylage and grass?
Hay: 85%
Haylage: 65%
Grass: 45%
Crib-biting increases the likelihood of which type of colic?
Gas-type colic
What should you check when investigating chronic GIT disease?
History-weight loss? Previous colic? Rectal exam Diet Teeth Worming history/faecal test Possible feed competition Next check serum proteins, the perform peritoneal fluid analysis
Tapeworms can cause colic in which location?
Ileo-caecal junction
How does chronic inflammatory disease affect globulins?
Causes hyperglobulinaemia
Give some causes of hyperfibrinogenaemia
Infection
Inflammation
Neoplasia
How can you investigate weight loss?
Oral glucose absorption test (SI): starve overnight, give 1gm/kg in a 20% soliton administered by nasogastric tube, measure absorption into blood
Rectal biopsy
Duodenal biopsy
Describe the results of an oral glucose absorption test
Normal: >85% increase in blood glucose concentration at 2 hours
Partial: 15-85% increases at 2 hours (SI or LI disease, or normal)
Complete:
From where should you take a rectal biopsy?
20-30cm inside rectum at 4 or 8 o clock
Take a small piece of mucosa
Where would you scan to view the stomach on an ultrasound?
8th-13th intercostal space, left side of abdomen
How do infiltrative bowel diseases cause weight loss?
Presence of inflammatory cells in intestinal wall -> malabsorption and protein-loss
How do you treat infiltrative bowel diseases?
Prednisolone
Dexamethasone
Anthelmintics
How do large and small strongyles affect the colon?
Large: verminous arteritis, thromboembolic colic
Small: submucosal inflammation
Give some haematological changes associated with parasitism?
Neutrophilia, hypoalbuminaemia, hyperglobulinaemia
NOT eosinophilia
What are the two divisions of equine gastric ulcer syndrome?
Give possible risk factors for each
EGGUS: Equine glandular gastric ulcer syndrome (bother horses mοre, harder to treat). Risk factors= possibly stress, NSAID-related.
ESGUS: Equine squamous gastric ulcer syndrome. Risk factor= acid injury.
What are the signs of EGUS (equine gastric ulcer syndrome)?
Weight loss, poor performance
Selective appetite, slow eating, prefer roughage over grain
Bad/cranky behaviou
Colic very unlikely
What is the pH in the two parts of the stomach?
Squamous portion prone to acid injury: pH 5.4
Glandular, acid-secreting portion protected from acid injury by mucous layer: 1.8
Where do ESGUS and EGGUS usually occur?
ESGUS: Caused by ‘splashing’ of stomach acid onto the unprotected mucosal lining above the margo plicatus, on squamous portion of stomach
EGGUS: below margo plicatus on glandular portion of stomach, when protective lining breaks down, exposing the mucosa to acids
Why is the horse so susceptible to gastric ulcers?
Stomach anatomy -> poor mixing of food, grain portion is rapidly fermentable -> acid production
Give some predisposing factors to acid injury leading to gastric ulcers
High concentrate diets -> volatile fatty acids and indirect acid injury via gastrin production in response to absorbed CHO (carbohydrates)
Also, low fibre concentrations -> reduced saliva production (saliva is an acid buffer)
Exercise -> gastrin production, also increased abdominal pressure can promote ‘splashing’ of acid onto unprotected squamous portion
How do you diagnose gastric ulcers?
Gastroscopy - 3m endoscope
Why is a faecal occult blood test not reliable for diagnosing gastric ulcers?
False negatives
How do you treat gastric ulcers?
Omeprazole (proton pump inhibitor)
- Buffered
- Enteric coated
- Plain
EGGUS requires higher doses
Give some clinical signs of colic in order of increasing severity
Flank watching Lying down Pawing the ground Rolling Repeatedly getting up and down Violent thrashing around
Give the different classifications of colic
Spasmodic Impactions Gas distension Obstructions (simple/ strangulating) Non-strangulating infarction Inflammation (enteritis/ colitis) Idiopathic
How do severe cases of colic lead to shock?
Loss of vascular supply to mucosa
Absorption of endotoxins into the circulation
Systemic inflammatory response system (SIRS)
What percentage of colic cases require surgery?
7%
What initial advice should you give to an owner of a horse with suspected colic?
Put horse in a well bedded stable
Remove anything it could injure itself on (buckets, feed etc)
Let horse roll if it wants to
A short period (10 mins) of walking exercise is fine but nothing longer before seeing a vet
Which sedative should you give to a horse with violently painful colic when examining it?
Xylazine iv (200mg for a 500kg horse) Also gives analgesia
Which questions should you ask a horse owner when investigating colic?
Which signs were observed?
When did these start/ when was the horse last normal?
Feed intake and faecal output over last 24 hours
Any diarrhoea?
History of equine grass sickness on premises?
Which structures are identifiable during a rectal palpation?
Pelvic flexure Caecum Spleen Nephrosplenic space Small (descending) colon Inguinal rings
What are some common findings when doing a rectal exam to investigate colic?
Distended SI Pelvic flexure impaction Left dorsal displacement Right dorsal displacement Large colon torsion Caecal impaction Small colon impaction
What sized needle should you use when doing an abdominocentesis?
18g, 1.5 inch
What is the appearance of normal peritoneal fluid?
Clear, straw-coloured
Regarding peritoneal fluid, what are the normal values for:
Total protein
WBCC
Lactate
Total protein:
What is the normal packed cell volume of a horse?
35-45%
What is the normal value for systemic total protein?
60-70g/L
Which diagnostic tests should you do when investigating colic?
Haematology (systemic lactate, WBC, systemic TP) Rectal exam Abdominocentesis Nasogastric intubation Ultrasound
What is the most common cause of colic in the foal?
Meconium impaction
What is the medical term for equine grass sickness?
Equine dysautonomia
What is the suspected cause of equine grass sickness?
What are the clinical signs?
Clostridium botulinum type C (exists in soil)
Acute, subacute, and chronic forms
Affects autonomic nervous system -> reduced GI motility
Causes a paralytic ileus (obstruction of ileum)
Patchy sweating, tachycardia
Fatal
What are the functions of the upper airways?
Channel for conveying airflow to and from lung
Filtering and conditioning of inspired air
Protection of lower airway from aspiration
Olfaction
Phonation
Swallowing
Thermoregulation
Why is a normal upper airway so critical in a horse in particular?
Because the horse is an obligate nasal breather
What is the tidal volume of a horse at rest?
5L
What is meant by tidal volume?
Lung volume, representing the normal volume of air displaced between normal inhalation and exhalation
What is the minute ventilation of a horse at rest and during exercise?
Rest: 75L
Exercise: 1500L (20x increase)
How do you work out minute ventilation?
Tidal volume x resp rate
Give some clinical signs of upper airway disease
Nasal discharge
Respiratory distress
Exercise intolerance
Noise at exercise
When investigating URT disease, what should you look out for regarding nasal discharge?
Is it unilateral/bilateral? (unilateral=lesion rostral to nasal septum) Chronicity Nature of discharge (blood/purulent/serous/food material) Recent head trauma? Recent URT infection? Is it associated with exercise? Any cough/ resp noise? Any facial swelling? Any response to treatment?
When investigating URT disease, what should you look out for regarding respiratory noise?
When does it occur (rest/ exercise?)
If it occurs at exercise, what pace does it occur at?
Is the noise inspiratory/ expiratory/ both?
What does it sound like? (Whistle, roar, gurgle, snoring)
Continuous/ intermittent?
If at exercise, does the horse stop/ slow down when it occurs?
Does the noise disappear once the horse’s speed reduces?
Does the noise limit the horse’s performance?
Does the horse recover normally after exercise?
When doing a clinical exam of the head, what should you look for?
Symmetry Nasal/ocular discharge Airflow from both nostrils Percussion of sinuses Palpation of larynx Evidence of previous surgical scars
In RLN (recurrent laryngeal neuropathy- roaring), which Cricoarytenoideus dorsalis muscle is atrophied?
Left
How can you determine whether a noise made at exercise is made during inspiration or expiration?
Expiration occurs as the leading leg hits the ground at canter and gallop
Is ‘roaring’ heard during inspiration or expiration?
Inspiration
Does dorsal displacement of the soft palate causes respiratory noises during inspiration or expiration?
Both:
Expiration= loud
Inspiration= soft gurgling
Give some causes of abnormal respiratory noises heard at exercise
RLN (recurrent laryngeal neuropathy) DDSP Epiglottic entrapment Subepiglottic cyst Epiglottic retroversion 4-BAD (fourth branchial arch defect) Alar fold collapse/ nasal paralysis ADAF (axial deviation of the aryepiglottic folds)
Which structures you examine with an endoscopy when investigating abnormal respiratory noises?
Nasal passages Sinus drainage angles Ethmoturbinates Nasopharynx Larynx Gutteral pouches
What is the only way of identifying causes of URT obstruction that only occur at exercise?
Exercise endoscopy (High speed treadmill endoscopy= gold standard Can also use dynamic respiratory endoscope-attaches to bridle)
How can you tell if a nasal obstruction is present above or below the nasal septum?
Rostral to nasal septum=unilateral discharge
Above nasal septum=bilateral discharge
When doing radiography, the latero-lateral view is good for assessing which structures?
Paranasal sinuses, gutteral pouches and pharynx
When doing radiography, lateral oblique views are good for assessing which structures?
Peri-apical regions of the premolars and molars (prevents superimposition)
When doing radiography, the dorso-ventral view is good for assessing which structures?
Paranasal sinuses, nasal septum and teeth
Helps to decode of lesions are unilateral or bilateral
Why might you perform a sinoscopy?
Investigate suspected paranasal sinus disease
Obtain material for biopsy
Treatment
Which diagnostic techniques might you use to investigate suspected masses?
MRI
CT scan
What is scintigraphy?
Radio isotopes are administered IV
The emitted radiation is measured by external detectors to produce 2D images
When might you use scintigraphy?
Investigation of orthopaedic disease (eg fracture identification)
Suspected TMJ disease
Identification of damaged tooth
Differentiation between primary and secondary sinusitis
How can you investigate alar folds collapse?
Temporary suture across bridge of nose, if resolves, alar folds collapse is cause of problem
Which bone separates the left and right nasal passages?
Nasal septum and vomer bone
The nasal passages are divided into which 3 sections?
Dorsal, middle, ventral meatus
What are the clinical signs of a problem with the nasal passages?
Nasal discharge Halitosis Abnormal respiratory noise Coughing Facial distortion Head shaking
How can you diagnose problems with the nasal passages?
Radiography
Ultrasound
CT scan
What is wry nose?
Congenital shortening of maxilla, nasal and vomer bones
Causes laterally deviated rostral maxilla and associated nasal septum deviation
Nasal obstruction
Usually accompanied by malocclusion of the teeth
Give some causes of disease in the nasal passages
Trauma Wry nose Deviation or thickening of the nasal septum Neoplasia (carcinoma) Progressive ethmoidal haematoma Fungal infection
When placing an nasogastric tube, which meatus should it pass through?
Ventral (less likely to damage ethmoturbinates)
Use lubricant on end of tube, don’t force it when you hit resistance
What is an ethmoid haematoma?
Encapsulated non-neoplastic mass
Grows into the nasal passages/paranasal sinuses
Unknown aetiology
What are the clinical signs of an ethmoid haematoma?
Mild intermittent unilateral epistaxis
Occasionally abnormal resp noise at exercise
+/- bad smell
How can you diagnose an ethmoid haematoma?
Endoscopy +/- radiography
CT scan
How do you treat an ethmoid haematoma?
Lesions in the nasal passages can be treated with intra-lesional formalin (causes aggressive necrosis of haematoma), however there is potential damage to sinus lining
Laser removal
Surgical removal
Recurrence common
What are the clinical signs of fungal rhinitis (nasal aspergillosis)?
How do you diagnose and treat it?
Unilateral purulent/ occasionally haemorrhagic nasal discharge
Foul smell
Occasionally nasal stertor
Diagnosis: endoscopy
Treatment: removal of fungal plaques and necrotic bone Topical treatment (nystatin powder)
Name the seven pairs of paranasal sinuses
Rostral maxillary Caudal maxillary Frontal Dorsal conchal Ventral conchal Sphenopalatine Ethmoid
How does drainage of sinuses occur?
Gravity and mucociliary action
Where do the other sinuses (apart from rostral maxillary and ventral conchal sinuses) drain?
Into the caudal maxillary sinus -> Middle meatus via the nasomaxillary aperture
What are the clinical signs of paranasal sinus disease?
Unilateral/bilateral nasal discharge (serous/purulent/mucopurulent/ occasionally haemorrhagic)
+/- facial swelling
+/- decreased nasal airflow (depending on amount of secondary oedema)
Fluid lines within a sinus on a radiograph indicate what?
Sinusitis
What is the difference between primary and secondary sinusitis?
Primary: usually results from previous resp tract infection, most commonly infection by streptococcus spp
Secondary: to bother condition, primarily dental disease die to the proximity of the alveolar bone to the maxillary sinuses (08, 09, 10, 11)
How do you treat primary sinusitis?
Rule out strep equi var equi (strangles)
Place on antibiotics eg trimethoprim sulphonamides for 7-14 days
Feed from the ground to encourage drainage
Dust-free management
Turnout as much as possible
Which structure may obstruct the drainage angle of the ventral conchal sinus?
Maxillary septal bulla
How may you surgically approach the paranasal sinuses?
Trephination or bone flap
How do you treat sinusitis that is secondary to peri-apical tooth infection?
Remove affected tooth
Flush sinuses
How do you treat sinusitis that is secondary to a facial fracture?
Remove/stabilise bone fragments
Flush sinuses
Give some clinical signs associated with paranasal sinus cysts
Facial swelling
Reduced nasal airflow
Nasal discharge
Nasal stertor
How do you treat a paranasal sinus cyst?
Surgical removal
What is suturitis?
Periostitis of the suture lines between the nasal and frontal bones
Bilateral firm non-painful swellings in the nasofrontal region
Usually regress with time
What are the two main functions of the pharynx?
Deliver air from the nasal cavity to the larynx
Provides a pathway for food from the oral cavity to the oesophagus
What separates the nasopharynx from the oropharynx?
Soft palate
Why does the pharynx have the potential to collapse during exercise?
Lacks rigid support by bone/cartilage
How does the pharynx retain stability?
Coordinated neuromuscular function
Which nerves innervate the pharynx?
Mandibular branch of trigeminal
Pharyngeal branch of vagus
Hypoglossal
Cervical nerves
What are the main functions of the larynx?
Breathing (communication between pharynx and trachea)
Protect lower airway (prevent inhalation of food during swallowing)
Phonation/ vocalisation
Which cartilages make up the larynx?
Cricoid cartilage
Thyroid cartilage
Epiglottis
Paired arytenoid cartilages
Which muscle is the principle abductor of the glottis?
When does it abduct the glottis?
Cricoarytenoideus dorsalis
Opens glottis during exercise
Which muscle is the principle adductor of the glottis?
When does it close the glottis?
Cricoarytenoidalis lateralis
Closes glottis during swallowing
When does the glottis open and close?
Open: exercise
Close: swallowing
Describe the slap test
Used to diagnose left recurrent laryngeal neuropathy (roaring)
Involves slapping one hemithorax to cause a reflex adduction of the muscular process of the arytenoid cartilage on the opposite side
Which diagnostic techniques can be used to examine the larynx and pharynx?
Endoscopy- exercise and at rest
Radiography
Ultrasound
Give some clinical signs associated with problems with the pharynx
Poor performance Respiratory noise Dysphagia (difficulty swallowing) Nasal discharge Coughing Respiratory distress
Give some diseases associated with the pharynx
Cleft palate Pharyngeal lymphoid hyperplasia DDSP (dorsal displacement of soft palate, can be persistent or intermittent) Palatal instability Pharyngeal collapse Pharyngeal mass Foreign body
When does intermittent dorsal displacement of the soft palate tend to occur?
What happens?
Intense exercise
Soft palate displaces dorsally resulting in an expiratory obstruction
Is intermittent or persistent dorsal displacement of the soft palate often secondary to other disease?
Persistent
Eg epiglottic entrapment, sub-epiglottic ulcer, sub-epiglottic cyst
Give some clinical signs of dorsal displacement of the soft palate
Exercise intolerance
Gurgling/vibrating noise
Rider reports ‘choking/swallowing its tongue’
How can you diagnose DDSP (dorsal displacement of soft palate)?
Endoscopy: resting (limited value) and during exercise (gold standard)
What is the function of thyrohyoideus?
Draws pharynx and larynx rostrally
What is a ‘tie-back’ procedure?
Operation to resolve roaring
Arytenoid cartilage is pulled to the side and sutured to keep it from interfering with airflow
What causes intermittent dorsal displacement of soft palate (IDDSP)?
Neuromuscular dysfunction:
- Pharyngeal branch of vagus nerve/Hypoglossal
- Thyrohyoideus
- Alteration in laryngohyoid position
- Inflammation
Which conservative treatment could you use to treat intermittent dorsal displacement of soft palate (IDDSP)?
Get horses fit
Change tack
Treat inflammatory conditions of the pharynx and gutteral pouch
Try throat support device?
How can you surgically treat dorsal displacement of the soft palate?
Staphylectomy: partial soft palate resection
Myectomy: removal of some of the extrinsic muscles of the larynx, reduced caudal retraction of the larynx
Induction of palatal fibrosis: thermal/laser cautery, stiffens soft palate
Tie forward: BEST, sutures placed between basihyoid bone and thyroid cartilage, positions larynx more rostrally and dorsally
How would you identify a foal with cleft palate?
Milk at nostril
What clinical signs are seen with laryngeal problems?
Respiratory noise Poor performance Dysphagia Coughing Respiratory distress
Explain recurrent laryngeal neuropathy
Common, large breeds
Unilateral paralysis of the left arytenoid cartilage
Progressive loss of myelinated nerve fibres in the left recurrent laryngeal nerve
Atrophy of cricoarytenoidalis dorsalis muscle
Loss of abductor and adductor function
How do you diagnose RLN (recurrent laryngeal neuropathy)?
Abnormal inspiratory noise at exercise - roaring
Poor performance
Clinical exam: +/- atrophy of CAD, negative result on slap test
Endoscopy at rest: asses synchrony of movement, ability to achieve and maintain full abduction (grade 1-4: Havemeyer scale)
Dynamic endoscopy is gold standard to asses degree of collapse during exercise
Describe the 4 grades of the Havemeyer scale when grading RLN (recurrent laryngeal neuropathy)
I: all arytenoid cartilage movements are synchronous and symmetrical. Full arytenoid abduction can be achieved and maintained.
II: arytenoid cartilage movements are asynchronous but full abduction can be achieved and maintained (sub-grades: 1.Transient 2.Permanent)
III. arytenoid cartilage movements are asynchronous and/or asymmetric. Full arytenoid abduction cannot be achieved and maintained (1.Occasions of symmetrical abduction 2.Obvious asymmetry 3.Marked but not total asymmetry)
IV. Complete immobility of the arytenoid cartilage and vocal fold
How can you treat RLN (recurrent laryngeal neuropathy)?
Ventriculectomy
Laryngoplasty (‘tie back’)
Describe a ventriculectomy procedure
Used to treat RLN (recurrent laryngeal neuropathy)
‘Hob day’ procedure
Roaring burr used to every left or both ventricles, which are then excised
+/- vocal cord removed at same time
Describe a ‘tie-back’ procedure
Used to treat RLN (recurrent laryngeal neuropathy)
Suture placed between dorsocaudal edge of cricoid cartilage and muscular process of arytenoid cartilage
Mimics the action of CAD (Cricoarytenoideus dorsalis)
Results in permanent abduction of left arytenoid cartilage
Give some complications of tie-back procedures
Failure Dysphagia Aspiration Persistent cough Infection
Give some causes of laryngeal paralysis (besides RLN)
Gutteral pouch disease
Peripheral neuropathy (eg liver disease)
Organophosphate poisoning
Fourth branchial arch arch defect (4BAD) affects which side of the larynx?
Right side
Explain fourth branchial arch defect
Variable development of the right laryngeal cartilage
Right-sided asymmetry
Rostral displacement of palatopharyngeal arch
Variable ability to abduct right arytenoid cartilage
What is vocal cord collapse (VCC) associated with?
ADAF
Axial deviation of aryepiglottic folds
Describe arytenoid chondritis
Mucosal ulceration
Infection of arytenoid cartilage
Progressive
Respiratory obstruction (younger TB, older mares)
What are the gutteral pouches?
Air-filled mucosa-lined outpouchings of the auditory tubes connecting the nasopharynx to the middle ear
Present in horses but no other domestic species
Paired
350ml in volume
Which structures border the gutteral pouches?
Dorsal: base of skull, first cervical vertebra, tympanic bulla, auditory meatus
Medial: median septum, rectus and longus capitis muscles
Ventral: nasopharynx, retropharyngeal lymph nodes
Lateral: parotid and mandibular salivary glands, Pterygoid muscles
How are gutteral pouches separated?
Separated into a medial and lateral compartment by the stylohyoid bone
Medial is bigger than lateral
Where do gutteral pouches empty?
Nasopharynx via a funnel-shaped orifice that has a fibrocartilage flap
Internal and external carotid arteries supply which compartment of gutteral pouches?
Internal: medial compartment
External: lateral compartment
What are the clinical signs of gutteral pouch disease?
Epistaxis Swelling/dyspnoea Nasal discharge Nerve dysfunction -dysphagia -laryngeal paralysis -Horner's syndrome (constructed pupil) -facial asymmetry
Give some diseases associated with gutteral pouches
Mycosis
Empyema/chondroids
Tympany
Otitis interna/media
Stylohyoid bone: temporohyoid osteopathy, fracture of petrous temporal/basisphenoid
Rupture of longus capitus ‘strap’ muscle
Neoplasia/cysts/foreign bodies
Describe gutteral pouch mycosis
Primary fungal plaque forms over vessels (most commonly internal carotid)
Uncommon but potentially life-threatening
What are the clinical signs of gutteral pouch mycosis?
Nasal discharge
Epistaxis
+/- nerve dysfunction: dysphagia, Horners (pupil constriction), laryngeal paralysis
How do you diagnose gutteral pouch mycosis?
Endoscopy
How do you treat gutteral pouch mycosis?
Surgical occlusion of affected artery: simple ligation (back flow from circle of Willis), or balloon catheterisation, or coil embolisation
Medical management if no history of bleeding: antifungals
Describe gutteral pouch empyema
Purulent material (chondroids) within one or both gutteral pouches
Usually in young horses
Aetiology: URT infection, irritant drugs
What are the clinical signs of gutteral pouch empyema?
Intermittent nasal discharge Parotid swelling and pain Extended head carriage Respiratory noise at rest Difficulty eating and swallowing Occasionally pharyngeal and laryngeal paresis
How do you diagnose gutteral pouch chondroids?
Radiography (increase radiodensity-whiteness- of gutteral pouches on lateral views
Endoscopy (dorsal pharyngeal compression, purulent material in gutteral pouches)
How do you treat chondroids?
Flushing of gutteral pouches using catheters inserted via sinus ostia (small openings connecting sinus to nasal pharynx)
Endoscopic removal of chondroids
Surgical flushing and removal of material
Describe gutteral pouch tympany
Foals
Usually unilateral
Marked retropharyngeal swelling
Clinical signs of: swelling, resp stridor, dysphagia
Confirmed on radiography or endoscopy
Tx: fenestration of membrane separating the two pouches to allow air to move into the non-affected pouch and leave through pharynx
Describe temporohyoid osteoarthropathy
Progressive disease of the middle ear and bones of the temporohyoid joint (stylohyoid bone, squamous portion of temporal bone)
Aetiology: Middle or inner ear infection
What are the clinical signs of temporohyoid osteoarthropathy?
Early: head shaking, ear rubbing, behavioural chane
Chronic: facial nerve paralysis, head tilt, ataxia, nystagmus (toward affected side)
What are the ‘strap’ muscles?
Longus capitus
Rectus capitus ventralis
Rectus capitus lateralis
Why may the ‘strap’ neck muscles rupture?
Trauma
Usually due to rearing and falling over backwards
Which clinical signs are associated with rupture of the ‘strap’ muscles?
Profuse bilateral epistaxis Ataxia Head tilt Pharyngeal and tracheal compression and secondary upper airway obstruction
How do you diagnose rupture of the neck ‘strap’ muscles?
Endoscopy: roof of pharynx collapsed, normal vessels, swollen muscle bellies
Radiography: fluid lines within gutteral pouch
What is the treatment for rupture of the neck ‘strap’ muscles?
Stall rest
Dependent on degree of concurrent brain trauma or skull fracture
Anti-inflammatories
Supportive care
When is a tracheotomy carried out?
Emergency bypass of URT obstruction
Route for intubation
Rest the URT
Bypass inoperable URT obstruction
How would you perform an emergency tracheotomy?
Clip a 20 x 10cm area on ventral midline at junction between middle and upper third of neck
Palpate paired sternothyrohyoideus muscles and tracheal rings
Give 10ml LA (eg mepivacaine) into skin and underlying tissues
Aseptically prepare site
Make a 6-8cm incision on ventral midline of neck
Palpate the two tracheal rings in the centre of the incision
Make a stab incision between the two rings
Extend the incision for 1-2cm each side of the midline
Insert tracheotomy tube
Secure in place
Give some differential diagnoses for dysphagia
Oesophageal obstruction Retropharyngeal abscess (eg strangles) Retropharyngeal mass (neoplasias, granuloma) Pharyngeal foreign body Gutteral pouch mycosis Equine grass sickness URT infection
Onchocerca cervicalis are found where?
Nuchal ligament
nematode
How big are pinworms?
2-13mm
What is the proper name for pinworm?
Oxyuris equi
What is urticaria?
Raised itchy rash
Wheals, oedema and pruritus
Sweet itch is caused by what?
Where on the horse is it seen?
Culicoides spp
Dorsal surface of horse: tail, mane, back
What does atopy mean?
Hyperallergic
How do you diagnose atopy?
Intradermal skin testing
What is the difference between scaling and crusting?
Scaling= dry, grey Crusting= yellow, red, brown, wet/damp
What is the difference between erosion and ulceration?
Erosion is superficial (partial loss of epithelial or mucosal surface that heals by resolution)
Ulceration is deeper (full thickness loss of epithelial or mucosal surface which heals by repair ie replacement with fibrous tissue)
Describe pemphigus foliaceus
Rare, autoimmune, horse makes antibodies against its own skin Severe crusting No age or sex predilection Dx: skin biopsy Tx: immunosuppressive drugs Prognosis: guarded
Viral papillomas are seen where?
Muzzle, face, pinna, inguinal area
Describe dermatophilosis congolensis
Gram +, facultative anaerobe, branching filaments on histology
Favourable conditions= skin trauma, wet skin
Thick, parakeratotic crusts (continuous epidermal invasion)
Tx: topical (mild cases), systemic antimicrobials (severe cases)
Bacterial folliculitis is caused by what?
Staphylococcus and streptococcus
Give an antifungal used to treat ringworm?
Miconazole
Describe leukocytoclastic vasculitis
Common, affects non-pigmented areas on distal limb
Results from deposition of immune complexes at vessel wall
Painful
Dx: skin biopsy
Tx: corticosteroids, avoid exposure to light
Describe pastern dermatitis
‘Greasy heel’ syndrome
Very common
Caused by chronic wetting of skin on distal heel
Winter, white limbs
What are warbles?
Larval stages of Hypoderma bovis and lineatum, appear as nodule with a central pore (larvae inside)
Neck and trunk
Often painful
Tx: enlargement of pore to remove central grub
What is an atheroma?
Degeneration of the walls of the arteries caused by accumulated fatty deposits and scar tissue
Leads to restriction of circulation -> thrombosis
What types of skin tumours are present in horses?
Sarcoids
Melanoma
Squamous cell carcinoma
Mast cell tumour
Describe sarcoids
Most common skin tumour in horses
Tumour of fibroblasts
Bovine papillomavirus 1 and 2 are most likely cause
6 clinical presentations: occult, verrucous, nodular, fibroblastic, mixed, malignant
Dx: biopsy
Tx: surgery, immune therapy, cytotoxics,
Where are melanomas usually seen?
Perineum, tail head (near anus), parotid region
How do you treat a melanoma?
Surgical excision, immunotherapy
Where are squamous cell carcinomas usually seen?
Poorly pigmented animals
External genitalia, eyes
Where are mast cell rumours found?
Head
Solitary
Males
How is equine herpes virus spread?
Mainly be respiratory route
Aborted foetus/ membranes/ vaginal discharge are highly contagious
What is the name of the equine roundworm?
Parascaris equorum
How do large and small strongyles affect the colon?
Large: verminous arteritis, thromboembolic colic
Small: submucosal inflammation
Give some haematological changes associated with parasitism?
Neutrophilia, hypoalbuminaemia, hyperglobulinaemia
NOT eosinophilia
What are the two divisions of equine gastric ulcer syndrome?
Give possible risk factors for each
EGGUS: Equine glandular gastric ulcer syndrome (bother horses mοre, harder to treat). Risk factors= possibly stress, NSAID-related.
ESGUS: Equine squamous gastric ulcer syndrome. Risk factor= acid injury.
What are the signs of EGUS (equine gastric ulcer syndrome)?
Weight loss, poor performance
Selective appetite, slow eating, prefer roughage over grain
Bad/cranky behaviou
Colic very unlikely
What is the pH in the two parts of the stomach?
Squamous portion prone to acid injury: pH 5.4
Glandular, acid-secreting portion protected from acid injury by mucous layer: 1.8
Where do ESGUS and EGGUS usually occur?
ESGUS: Caused by ‘splashing’ of stomach acid onto the unprotected mucosal lining above the margo plicatus, on squamous portion of stomach
EGGUS: below margo plicatus on glandular portion of stomach, when protective lining breaks down, exposing the mucosa to acids
Why is the horse so susceptible to gastric ulcers?
Stomach anatomy -> poor mixing of food, grain portion is rapidly fermentable -> acid production
Give some predisposing factors to acid injury leading to gastric ulcers
High concentrate diets -> volatile fatty acids and indirect acid injury via gastrin production in response to absorbed CHO (carbohydrates)
Also, low fibre concentrations -> reduced saliva production (saliva is an acid buffer)
Exercise -> gastrin production, also increased abdominal pressure can promote ‘splashing’ of acid onto unprotected squamous portion
How do you diagnose gastric ulcers?
Gastroscopy - 3m endoscope
Why is a faecal occult blood test not reliable for diagnosing gastric ulcers?
False negatives
How do you treat gastric ulcers?
Omeprazole (proton pump inhibitor)
- Buffered
- Enteric coated
- Plain
EGGUS requires higher doses
Give some clinical signs of colic in order of increasing severity
Flank watching Lying down Pawing the ground Rolling Repeatedly getting up and down Violent thrashing around
Give the different classifications of colic
Spasmodic Impactions Gas distension Obstructions (simple/ strangulating) Non-strangulating infarction Inflammation (enteritis/ colitis) Idiopathic
How do severe cases of colic lead to shock?
Loss of vascular supply to mucosa
Absorption of endotoxins into the circulation
Systemic inflammatory response system (SIRS)
What percentage of colic cases require surgery?
7%
What initial advice should you give to an owner of a horse with suspected colic?
Put horse in a well bedded stable
Remove anything it could injure itself on (buckets, feed etc)
Let horse roll if it wants to
A short period (10 mins) of walking exercise is fine but nothing longer before seeing a vet
Which sedative should you give to a horse with colic when examining it?
Xylazine iv (200mg for a 500kg horse) Also gives analgesia
Which questions should you ask a horse owner when investigating colic?
Which signs were observed?
When did these start/ when was the horse last normal?
Feed intake and faecal output over last 24 hours
Any diarrhoea?
History of equine grass sickness on premises?
Which structures are identifiable during a rectal palpation?
Pelvic flexure Caecum Spleen Nephrosplenic space Small (descending) colon Inguinal rings
What are some common findings when doing a rectal exam to investigate colic?
Distended SI Pelvic flexure impaction Left dorsal displacement Right dorsal displacement Large colon torsion Caecal impaction Small colon impaction
What sized needle should you use when doing an abdominocentesis?
18g, 1.5 inch
What is the appearance of normal peritoneal fluid?
Clear, straw-coloured
Regarding peritoneal fluid, what are the normal values for:
Total protein
WBCC
Lactate
Total protein:
What is the normal packed cell volume of a horse?
35-45%
What is the normal value for systemic total protein?
60-70g/L
Which diagnostic tests should you do when investigating colic?
Haematology (systemic lactate, WBC, systemic TP) Rectal exam Abdominocentesis Nasogastric intubation Ultrasound
What is the most common cause of colic in the foal?
Meconium impaction
What is the medical term for equine grass sickness?
Equine dysautonomia
What is the suspected cause of equine grass sickness?
Clostridium botulinum type C (exists in soil)
Acute, subacute, and chronic forms
Affects autonomic nervous system -> reduced GI motility
Causes a paralytic ileus (obstruction of ileum)
Patchy sweating, tachycardia
Fatal
What are the functions of the upper airways?
Channel for conveying airflow to and from lung
Filtering and conditioning of inspired air
Protection of lower airway from aspiration
Olfaction
Phonation
Swallowing
Thermoregulation
Why is a normal upper airway so critical in a horse in particular?
Because the horse is an obligate nasal breather
What is the tidal volume of a horse at rest?
5L
What is meant by tidal volume?
Lung volume, representing the normal volume of air displaced between normal inhalation and exhalation
What is the minute ventilation of a horse at rest and during exercise?
Rest: 75L
Exercise: 1500L (20x increase)
How do you work out minute ventilation?
Tidal volume x resp rate
Give some clinical signs of upper airway disease
Nasal discharge
Respiratory distress
Exercise intolerance
Noise at exercise
When investigating URT disease, what should you look out for regarding nasal discharge?
Is it unilateral/bilateral? Chronicity Nature of discharge (blood/purulent/serous/food material) Recent head trauma? Recent URT infection? Is it associated with exercise? Any cough/ resp noise? Any facial swelling? Any response to treatment?
When investigating URT disease, what should you look out for regarding respiratory noise?
When does it occur (rest/ exercise?)
If it occurs at exercise, what pace does it occur at?
Is the noise inspiratory/ expiratory/ both?
What does it sound like? (Whistle, roar, gurgle, snoring)
Continuous/ intermittent?
If at exercise, does the horse stop/ slow down when it occurs?
Does the noise disappear once the horse’s speed reduces?
Does the noise limit the horse’s performance?
Does the horse recover normally after exercise?
When doing a clinical exam of the head, what should you look for?
Symmetry Nasal/ocular discharge Airflow from both nostrils Percussion of sinuses Palpation of larynx Evidence of previous surgical scars
In RLN (recurrent laryngeal neuropathy- roaring), which Cricoarytenoideus dorsalis muscle is atrophied?
Left
How can you determine whether a noise made at exercise is made during inspiration or expiration?
Expiration occurs as the leading leg hits the ground at canter and gallop
Is ‘roaring’ heard during inspiration or expiration?
Inspiration
Does dorsal displacement of the soft palate causes respiratory noises during inspiration or expiration?
Both:
Expiration= loud
Inspiration= soft gurgling
Give some causes of abnormal respiratory noises heard at exercise
RLN (recurrent laryngeal neuropathy) DDSP Epiglottic entrapment Subepiglottic cyst Epiglottic retroversion 4-BAD (fourth branchial arch defect) Alar fold collapse/ nasal paralysis ADAF (axial deviation of the aryepiglottic folds)
Which structures you examine with an endoscopy when investigating abnormal respiratory noises?
Nasal passages Sinus drainage angles Ethmoturbinates Nasopharynx Larynx Gutteral pouches
What is the only way of identifying causes of URT obstruction that only occur at exercise?
Exercise endoscopy (High speed treadmill endoscopy= gold standard Can also use dynamic respiratory endoscope-attaches to bridle)
How can you tell if a nasal obstruction is present above or below the nasal septum?
Rostral to nasal septum=unilateral discharge
Above nasal septum=bilateral discharge
When doing radiography, the latero-lateral view is good for assessing which structures?
Paranasal sinuses, gutteral pouches and pharynx
When doing radiography, lateral oblique views are good for assessing which structures?
Peri-apical regions of the premolars and molars (prevents superimposition)
When doing radiography, the dorso-ventral view is good for assessing which structures?
Paranasal sinuses, nasal septum and teeth
Helps to decode of lesions are unilateral or bilateral
Why might you perform a sinoscopy?
Investigate suspected paranasal sinus disease
Obtain material for biopsy
Treatment
Which diagnostic techniques might you use to investigate suspected masses?
MRI
CT scan
What is scintigraphy?
Radio isotopes are administered IV
The emitted radiation is measured by external detectors to produce 2D images
When might you use scintigraphy?
Investigation of orthopaedic disease (eg fracture identification)
Suspected TMJ disease
Identification of damaged tooth
Differentiation between primary and secondary sinusitis
How can you investigate alar folds collapse?
Temporary suture across bridge of nose, if resolves, alar folds collapse is cause of problem
Which bone separates the left and right nasal passages?
Nasal septum and vomer bone
The nasal passages are divided into which 3 sections?
Dorsal, middle, ventral meatus
What are the clinical signs of a problem with the nasal passages?
Nasal discharge Halitosis Abnormal respiratory noise Coughing Facial distortion Head shaking
How can you diagnose problems with the nasal passages?
Radiography
Ultrasound
CT scan
What is wry nose?
Congenital shortening of maxilla, nasal and vomer bones
Causes laterally deviated rostral maxilla and associated nasal septum deviation
Nasal obstruction
Usually accompanied by malocclusion of the teeth
Give some causes of disease in the nasal passages
Trauma Wry nose Deviation or thickening of the nasal septum Neoplasia (carcinoma) Progressive ethmoidal haematoma Fungal infection
When placing an nasogastric tube, which meatus should it pass through?
Ventral (less likely to damage ethmoturbinates)
Use lubricant on end of tube, don’t force it when you hit resistance
What is an ethmoid haematoma?
Encapsulated non-neoplastic mass
Grows into the nasal passages/paranasal sinuses
Unknown aetiology
What are the clinical signs of an ethmoid haematoma?
Mild intermittent unilateral epistaxis
Occasionally abnormal resp noise at exercise
+/- bad smell
How can you diagnose an ethmoid haematoma?
Endoscopy +/- radiography
CT scan
How do you treat an ethmoid haematoma?
Lesions in the nasal passages can be treated with intra-lesional formalin (causes aggressive necrosis of haematoma), however there is potential damage to sinus lining
Laser removal
Surgical removal
Recurrence common
What are the clinical signs of fungal rhinitis (nasal aspergillosis)?
How do you diagnose and treat it?
Unilateral purulent/ occasionally haemorrhagic nasal discharge
Foul smell
Occasionally nasal stertor
Diagnosis: endoscopy
Treatment: removal of fungal plaques and necrotic bone Topical treatment (nystatin powder)
Name the seven pairs of paranasal sinuses
Rostral maxillary Caudal maxillary Frontal Dorsal conchal Ventral conchal Sphenopalatine Ethmoid
How does drainage of sinuses occur?
Gravity and mucociliary action
Where do the other sinuses (apart from rostral maxillary and ventral conchal sinuses) drain?
Into the caudal maxillary sinus -> Middle meatus via the nasomaxillary aperture
What are the clinical signs of paranasal sinus disease?
Unilateral/bilateral nasal discharge (serous/purulent/mucopurulent/ occasionally haemorrhagic)
+/- facial swelling
+/- decreased nasal airflow (depending on amount of secondary oedema)
Fluid lines within a sinus on a radiograph indicate what?
Sinusitis
What is the difference between primary and secondary sinusitis?
Primary: usually results from previous resp tract infection, most commonly infection by streptococcus spp
Secondary: to bother condition, primarily dental disease die to the proximity of the alveolar bone to the maxillary sinuses (08, 09, 10, 11)
How do you treat primary sinusitis?
Rule out strep equi var equi (strangles)
Place on antibiotics eg trimethoprim sulphonamides for 7-14 days
Feed from the ground to encourage drainage
Dust-free management
Turnout as much as possible
Which structure may obstruct the drainage angle of the ventral conchal sinus?
Maxillary septal bulla
How may you surgically approach the paranasal sinuses?
Trephination or bone flap
How do you treat sinusitis that is secondary to peri-apical tooth infection?
Remove affected tooth
Flush sinuses
How do you treat sinusitis that is secondary to a facial fracture?
Remove/stabilise bone fragments
Flush sinuses
Give some clinical signs associated with paranasal sinus cysts
Facial swelling
Reduced nasal airflow
Nasal discharge
Nasal stertor
How do you treat a paranasal sinus cyst?
Surgical removal
What is suturitis?
Periostitis of the suture lines between the nasal and frontal bones
Bilateral firm non-painful swellings in the nasofrontal region
Usually regress with time
What are the two main functions of the pharynx?
Deliver air from the nasal cavity to the larynx
Provides a pathway for food from the oral cavity to the oesophagus
What separates the nasopharynx from the oropharynx?
Soft palate
Why does the pharynx have the potential to collapse during exercise?
Lacks rigid support by bone/cartilage
How does the pharynx retain stability?
Coordinated neuromuscular function
Which nerves innervate the pharynx?
Mandibular branch of trigeminal
Pharyngeal branch of vagus
Hypoglossal
Cervical nerves
What are the main functions of the larynx?
Breathing (communication between pharynx and trachea)
Protect lower airway (prevent inhalation of food during swallowing)
Phonation/ vocalisation
Which cartilages make up the larynx?
Cricoid cartilage
Thyroid cartilage
Epiglottis
Paired arytenoid cartilages
Which muscle is the principle abductor of the glottis?
Cricoarytenoideus dorsalis
Which muscle is the principle adductor of the glottis?
Cricoarytenoidalis lateralis
When does the glottis open and close?
Open: exercise
Close: swallowing
Describe the slap test
Used to diagnose left recurrent laryngeal neuropathy (roaring)
Involves slapping one hemithorax to cause a reflex adduction of the muscular process of the arytenoid cartilage on the opposite side
Which diagnostic techniques can be used to examine the larynx and pharynx?
Endoscopy- exercise and at rest
Radiography
Ultrasound
Give some clinical signs associated with problems with the pharynx
Poor performance Respiratory noise Dysphagia (difficulty swallowing) Nasal discharge Coughing Respiratory distress
Give some diseases associated with the pharynx
Cleft palate Pharyngeal lymphoid hyperplasia DDSP (dorsal displacement of soft palate, can be persistent or intermittent) Palatal instability Pharyngeal collapse Pharyngeal mass Foreign body
When does intermittent dorsal displacement of the soft palate tend to occur?
What happens?
Intense exercise
Soft palate displaces dorsally resulting in an expiratory obstruction
Is intermittent or persistent dorsal displacement of the soft palate often secondary to other disease?
Persistent
Eg epiglottic entrapment, sub-epiglottic ulcer, sub-epiglottic cyst
Give some clinical signs of dorsal displacement of the soft palate
Exercise intolerance
Gurgling/vibrating noise
Rider reports ‘choking/swallowing its tongue’
How can you diagnose DDSP (dorsal displacement of soft palate)?
Endoscopy: resting (limited value) and during exercise (gold standard)
What is the function of thyrohyoideus?
Draws pharynx and larynx rostrally
What is a ‘tie-back’ procedure?
Operation to resolve roaring
Arytenoid cartilage is pulled to the side and sutured to keep it from interfering with airflow
What causes intermittent dorsal displacement of soft palate (IDDSP)?
Neuromuscular dysfunction:
- Pharyngeal branch of vagus nerve/Hypoglossal
- Thyrohyoideus
- Alteration in laryngohyoid position
- Inflammation
Which conservative treatment could you use to treat intermittent dorsal displacement of soft palate (IDDSP)?
Get horses fit
Change tack
Treat inflammatory conditions of the pharynx and gutteral pouch
Try throat support device?
How can you surgically treat dorsal displacement of the soft palate?
Staphylectomy: partial soft palate resection
Myectomy: removal of some of the extrinsic muscles of the larynx, reduced caudal retraction of the larynx
Induction of palatal fibrosis: thermal/laser cautery, stiffens soft palate
Tie forward: BEST, sutures placed between basihyoid bone and thyroid cartilage, positions larynx more rostrally and dorsally
How would you identify a foal with cleft palate?
Milk at nostril
What clinical signs are seen with laryngeal problems?
Respiratory noise Poor performance Dysphagia Coughing Respiratory distress
Explain recurrent laryngeal neuropathy
Common, large breeds
Unilateral paralysis of the left arytenoid cartilage
Progressive loss of myelinated nerve fibres in the left recurrent laryngeal nerve
Atrophy of cricoarytenoidalis dorsalis muscle
Loss of abductor and adductor function
How do you diagnose RLN (recurrent laryngeal neuropathy)?
Abnormal inspiratory noise at exercise - roaring
Poor performance
Clinical exam: +/- atrophy of CAD, negative result on slap test
Endoscopy at rest: asses synchrony of movement, ability to achieve and maintain full abduction (grade 1-4: Havemeyer scale)
Dynamic endoscopy is gold standard to asses degree of collapse during exercise
Describe the 4 grades of the Havemeyer scale when grading RLN (recurrent laryngeal neuropathy)
I: all arytenoid cartilage movements are synchronous and symmetrical. Full arytenoid abduction can be achieved and maintained.
II: arytenoid cartilage movements are asynchronous but full abduction can be achieved and maintained (sub-grades: 1.Transient 2.Permanent)
III. arytenoid cartilage movements are asynchronous and/or asymmetric. Full arytenoid abduction cannot be achieved and maintained (1.Occasions of symmetrical abduction 2.Obvious asymmetry 3.Marked but not total asymmetry)
IV. Complete immobility of the arytenoid cartilage and vocal fold
How can you treat RLN (recurrent laryngeal neuropathy)?
Ventriculectomy
Laryngoplasty (‘tie back’)
Describe a ventriculectomy procedure
Used to treat RLN (recurrent laryngeal neuropathy)
‘Hob day’ procedure
Roaring burr used to every left or both ventricles, which are then excised
+/- vocal cord removed at same time
Describe a ‘tie-back’ procedure
Used to treat RLN (recurrent laryngeal neuropathy)
Suture placed between dorsocaudal edge of cricoid cartilage and muscular process of arytenoid cartilage
Mimics the action of CAD (Cricoarytenoideus dorsalis)
Results in permanent abduction of left arytenoid cartilage
Give some complications of tie-back procedures
Failure Dysphagia Aspiration Persistent cough Infection
Give some causes of laryngeal paralysis (besides RLN)
Gutteral pouch disease
Peripheral neuropathy (eg liver disease)
Organophosphate poisoning
Fourth branchial arch arch defect (4BAD) affects which side of the larynx?
Right side
Explain fourth branchial arch defect
Variable development of the right laryngeal cartilage
Right-sided asymmetry
Rostral displacement of palatopharyngeal arch
Variable ability to abduct right arytenoid cartilage
What is vocal cord collapse (VCC) associated with?
ADAF
Axial deviation of aryepiglottic folds
Describe arytenoid chondritis
Mucosal ulceration
Infection of arytenoid cartilage
Progressive
Respiratory obstruction (younger TB, older mares)
What are the gutteral pouches?
Air-filled mucosa-lined outpouchings of the auditory tubes connecting the nasopharynx to the middle ear
Present in horses but no other domestic species
Paired
350ml in volume
Which structures border the gutteral pouches?
Dorsal: base of skull, first cervical vertebra, tympanic bulla, auditory meatus
Medial: median septum, rectus and longus capitis muscles
Ventral: nasopharynx, retropharyngeal lymph nodes
Lateral: parotid and mandibular salivary glands, Pterygoid muscles
How are gutteral pouches separated?
Separated into a medial and lateral compartment by the stylohyoid bone
Medial is bigger than lateral
Where do gutteral pouches empty?
Nasopharynx via a funnel-shaped orifice that has a fibrocartilage flap
Internal and external carotid arteries supply which compartment of gutteral pouches?
Internal: medial compartment
External: lateral compartment
What are the clinical signs of gutteral pouch disease?
Epistaxis Swelling/dyspnoea Nasal discharge Nerve dysfunction -dysphagia -laryngeal paralysis -Horner's syndrome (constructed pupil) -facial asymmetry
Give some diseases associated with gutteral pouches
Mycosis
Empyema/chondroids
Tympany
Otitis interna/media
Stylohyoid bone: temporohyoid osteopathy, fracture of petrous temporal/basisphenoid
Rupture of longus capitus ‘strap’ muscle
Neoplasia/cysts/foreign bodies
Describe gutteral pouch mycosis
Primary fungal plaque forms over vessels (most commonly internal carotid)
Uncommon but potentially life-threatening
What are the clinical signs of gutteral pouch mycosis?
Nasal discharge
Epistaxis
+/- nerve dysfunction: dysphagia, Horners (pupil constriction), laryngeal paralysis
How do you diagnose gutteral pouch mycosis?
Endoscopy
How do you treat gutteral pouch mycosis?
Surgical occlusion of affected artery: simple ligation (back flow from circle of Willis), or balloon catheterisation, or coil embolisation
Medical management if no history of bleeding: antifungals
Describe gutteral pouch empyema
Purulent material (chondroids) within one or both gutteral pouches
Usually in young horses
Aetiology: URT infection, irritant drugs
What are the clinical signs of gutteral pouch empyema?
Intermittent nasal discharge Parotid swelling and pain Extended head carriage Respiratory noise at rest Difficulty eating and swallowing Occasionally pharyngeal and laryngeal paresis
How do you diagnose gutteral pouch chondroids?
Radiography (increase radiodensity-whiteness- of gutteral pouches on lateral views
Endoscopy (dorsal pharyngeal compression, purulent material in gutteral pouches)
How do you treat chondroids?
Flushing of gutteral pouches using catheters inserted via sinus ostia (small openings connecting sinus to nasal pharynx)
Endoscopic removal of chondroids
Surgical flushing and removal of material
Describe gutteral pouch tympany
Foals Usually unilateral Marked retropharyngeal swelling Clinical signs of: swelling, resp stridor, dysphagia Confirmed on radiography or endoscopy
Describe temporohyoid osteoarthropathy
Progressive disease of the middle ear and bones of the temporohyoid joint (stylohyoid bone, squamous portion of temporal bone)
Aetiology: Middle or inner ear infection
What are the clinical signs of temporohyoid osteoarthropathy?
Early: head shaking, ear rubbing, behavioural chane
Chronic: facial nerve paralysis, head tilt, ataxia, nystagmus (toward affected side)
What are the ‘strap’ muscles?
Longus capitus
Rectus capitus ventralis
Rectus capitus lateralis
Why may the ‘strap’ neck muscles rupture?
Trauma
Usually due to rearing and falling over backwards
Which clinical signs are associated with rupture of the ‘strap’ muscles?
Profuse bilateral epistaxis Ataxia Head tilt Pharyngeal and tracheal compression and secondary upper airway obstruction
How do you diagnose rupture of the neck ‘strap’ muscles?
Endoscopy: roof of pharynx collapsed, normal vessels, swollen muscle bellies
Radiography: fluid lines within gutteral pouch
What is the treatment for rupture of the neck ‘strap’ muscles?
Stall rest
Dependent on degree of concurrent brain trauma or skull fracture
Anti-inflammatories
Supportive care
When is a tracheotomy carried out?
Emergency bypass of URT obstruction
Route for intubation
Rest the URT
Bypass inoperable URT obstruction
How would you perform an emergency tracheotomy?
Clip a 20 x 10cm area on ventral midline at junction between middle and upper third of neck
Palpate paired sternothyrohyoideus muscles and tracheal rings
Give 10ml LA (eg mepivacaine) into skin and underlying tissues
Aseptically prepare site
Make a 6-8cm incision on ventral midline of neck
Palpate the two tracheal rings in the centre of the incision
Make a stab incision between the two rings
Extend the incision for 1-2cm each side of the midline
Insert tracheotomy tube
Secure in place
Give some differential diagnoses for dysphagia
Oesophageal obstruction Retropharyngeal abscess (eg strangles) Retropharyngeal mass (neoplasias, granuloma) Pharyngeal foreign body Gutteral pouch mycosis Equine grass sickness URT infection
Onchocerca cervicalis are found where?
Nuchal ligament
nematode
How big are pinworms?
2-13mm
What is the proper name for pinworm?
Oxyuris equi
What is urticaria?
Raised itchy rash
Wheals, oedema and pruritus
Sweet itch is caused by what?
Where on the horse is it seen?
Culicoides spp
Dorsal surface of horse: tail, mane, back
What does atopy mean?
Hyperallergic
How do you diagnose atopy?
Intradermal skin testing
What is the difference between scaling and crusting?
Scaling= dry, grey Crusting= yellow, red, brown, wet/damp
What is the difference between erosion and ulceration?
Erosion is superficial (partial loss of epithelial or mucosal surface that heals by resolution)
Ulceration is deeper (full thickness loss of epithelial or mucosal surface which heals by repair ie replacement with fibrous tissue)
Describe pemphigus foliaceus
Rare, autoimmune, horse makes antibodies against its own skin Severe crusting No age or sex predilection Dx: skin biopsy Tx: immunosuppressive drugs Prognosis: guarded
Viral papillomas are seen where?
Muzzle, face, pinna, inguinal area
Describe dermatophilosis congolensis
Gram +, facultative anaerobe, branching filaments on histology
Favourable conditions= skin trauma, wet skin
Thick, parakeratotic crusts (continuous epidermal invasion)
Tx: topical (mild cases), systemic antimicrobials (severe cases)
Bacterial folliculitis is caused by what?
Staphylococcus and streptococcus
Give an antifungal used to treat ringworm?
Miconazole
Describe leukocytoclastic vasculitis
Common, affects non-pigmented areas on distal limb
Results from deposition of immune complexes at vessel wall
Painful
Dx: skin biopsy
Tx: corticosteroids, avoid exposure to light
Describe pastern dermatitis
‘Greasy heel’ syndrome
Very common
Caused by chronic wetting of skin on distal heel
Winter, white limbs
What are warbles?
Larval stages of Hypoderma bovis and lineatum, appear as nodule with a central pore (larvae inside)
Neck and trunk
Often painful
Tx: enlargement of pore to remove central grub
What is an atheroma?
Degeneration of the walls of the arteries caused by accumulated fatty deposits and scar tissue
Leads to restriction of circulation -> thrombosis
What types of skin tumours are present in horses?
Sarcoids
Melanoma
Squamous cell carcinoma
Mast cell tumour
Describe sarcoids
Most common skin tumour in horses
Tumour of fibroblasts
Bovine papillomavirus 1 and 2 are most likely cause
6 clinical presentations: occult, verrucous, nodular, fibroblastic, mixed, malignant
Dx: biopsy
Tx: surgery, immune therapy, cytotoxics,
Where are melanomas usually seen?
Perineum, tail head (near anus), parotid region
How do you treat a melanoma?
Surgical excision, immunotherapy
Where are squamous cell carcinomas usually seen?
Poorly pigmented animals
External genitalia, eyes
Where are mast cell rumours found?
Head
Solitary
Males
How is equine herpes virus spread?
Mainly be respiratory route
Aborted foetus/ membranes/ vaginal discharge are highly contagious
How do large and small strongyles affect the colon?
Large: verminous arteritis, thromboembolic colic
Small: submucosal inflammation
Give some haematological changes associated with parasitism?
Neutrophilia, hypoalbuminaemia, hyperglobulinaemia
NOT eosinophilia
What are the two divisions of equine gastric ulcer syndrome?
Give possible risk factors for each
EGGUS: Equine glandular gastric ulcer syndrome (bother horses mοre, harder to treat). Risk factors= possibly stress, NSAID-related.
ESGUS: Equine squamous gastric ulcer syndrome. Risk factor= acid injury.
What are the signs of EGUS (equine gastric ulcer syndrome)?
Weight loss, poor performance
Selective appetite, slow eating, prefer roughage over grain
Bad/cranky behaviou
Colic very unlikely
What is the pH in the two parts of the stomach?
Squamous portion prone to acid injury: pH 5.4
Glandular, acid-secreting portion protected from acid injury by mucous layer: 1.8
Where do ESGUS and EGGUS usually occur?
ESGUS: Caused by ‘splashing’ of stomach acid onto the unprotected mucosal lining above the margo plicatus, on squamous portion of stomach
EGGUS: below margo plicatus on glandular portion of stomach, when protective lining breaks down, exposing the mucosa to acids
Why is the horse so susceptible to gastric ulcers?
Stomach anatomy -> poor mixing of food, grain portion is rapidly fermentable -> acid production
Give some predisposing factors to acid injury leading to gastric ulcers
High concentrate diets -> volatile fatty acids and indirect acid injury via gastrin production in response to absorbed CHO (carbohydrates)
Also, low fibre concentrations -> reduced saliva production (saliva is an acid buffer)
Exercise -> gastrin production, also increased abdominal pressure can promote ‘splashing’ of acid onto unprotected squamous portion
How do you diagnose gastric ulcers?
Gastroscopy - 3m endoscope
Why is a faecal occult blood test not reliable for diagnosing gastric ulcers?
False negatives
How do you treat gastric ulcers?
Omeprazole (proton pump inhibitor)
- Buffered
- Enteric coated
- Plain
EGGUS requires higher doses
Give some clinical signs of colic in order of increasing severity
Flank watching Lying down Pawing the ground Rolling Repeatedly getting up and down Violent thrashing around
Give the different classifications of colic
Spasmodic Impactions Gas distension Obstructions (simple/ strangulating) Non-strangulating infarction Inflammation (enteritis/ colitis) Idiopathic
How do severe cases of colic lead to shock?
Loss of vascular supply to mucosa
Absorption of endotoxins into the circulation
Systemic inflammatory response system (SIRS)
What percentage of colic cases require surgery?
7%
What initial advice should you give to an owner of a horse with suspected colic?
Put horse in a well bedded stable
Remove anything it could injure itself on (buckets, feed etc)
Let horse roll if it wants to
A short period (10 mins) of walking exercise is fine but nothing longer before seeing a vet
Which sedative should you give to a horse with colic when examining it?
Xylazine iv (200mg for a 500kg horse) Also gives analgesia
Which questions should you ask a horse owner when investigating colic?
Which signs were observed?
When did these start/ when was the horse last normal?
Feed intake and faecal output over last 24 hours
Any diarrhoea?
History of equine grass sickness on premises?
Which structures are identifiable during a rectal palpation?
Pelvic flexure Caecum Spleen Nephrosplenic space Small (descending) colon Inguinal rings
What are some common findings when doing a rectal exam to investigate colic?
Distended SI Pelvic flexure impaction Left dorsal displacement Right dorsal displacement Large colon torsion Caecal impaction Small colon impaction
What sized needle should you use when doing an abdominocentesis?
18g, 1.5 inch
What is the appearance of normal peritoneal fluid?
Clear, straw-coloured
Regarding peritoneal fluid, what are the normal values for:
Total protein
WBCC
Lactate
Total protein:
What is the normal packed cell volume of a horse?
35-45%
What is the normal value for systemic total protein?
60-70g/L
Which diagnostic tests should you do when investigating colic?
Haematology (systemic lactate, WBC, systemic TP) Rectal exam Abdominocentesis Nasogastric intubation Ultrasound
What is the most common cause of colic in the foal?
Meconium impaction
What is the medical term for equine grass sickness?
Equine dysautonomia
What is the suspected cause of equine grass sickness?
Clostridium botulinum type C (exists in soil)
Acute, subacute, and chronic forms
Affects autonomic nervous system -> reduced GI motility
Causes a paralytic ileus (obstruction of ileum)
Patchy sweating, tachycardia
Fatal
What are the functions of the upper airways?
Channel for conveying airflow to and from lung
Filtering and conditioning of inspired air
Protection of lower airway from aspiration
Olfaction
Phonation
Swallowing
Thermoregulation
Why is a normal upper airway so critical in a horse in particular?
Because the horse is an obligate nasal breather
What is the tidal volume of a horse at rest?
5L
What is meant by tidal volume?
Lung volume, representing the normal volume of air displaced between normal inhalation and exhalation
What is the minute ventilation of a horse at rest and during exercise?
Rest: 75L
Exercise: 1500L (20x increase)
How do you work out minute ventilation?
Tidal volume x resp rate
Give some clinical signs of upper airway disease
Nasal discharge
Respiratory distress
Exercise intolerance
Noise at exercise
When investigating URT disease, what should you look out for regarding nasal discharge?
Is it unilateral/bilateral? Chronicity Nature of discharge (blood/purulent/serous/food material) Recent head trauma? Recent URT infection? Is it associated with exercise? Any cough/ resp noise? Any facial swelling? Any response to treatment?
When investigating URT disease, what should you look out for regarding respiratory noise?
When does it occur (rest/ exercise?)
If it occurs at exercise, what pace does it occur at?
Is the noise inspiratory/ expiratory/ both?
What does it sound like? (Whistle, roar, gurgle, snoring)
Continuous/ intermittent?
If at exercise, does the horse stop/ slow down when it occurs?
Does the noise disappear once the horse’s speed reduces?
Does the noise limit the horse’s performance?
Does the horse recover normally after exercise?
When doing a clinical exam of the head, what should you look for?
Symmetry Nasal/ocular discharge Airflow from both nostrils Percussion of sinuses Palpation of larynx Evidence of previous surgical scars
In RLN (recurrent laryngeal neuropathy- roaring), which Cricoarytenoideus dorsalis muscle is atrophied?
Left
How can you determine whether a noise made at exercise is made during inspiration or expiration?
Expiration occurs as the leading leg hits the ground at canter and gallop
Is ‘roaring’ heard during inspiration or expiration?
Inspiration
Does dorsal displacement of the soft palate causes respiratory noises during inspiration or expiration?
Both:
Expiration= loud
Inspiration= soft gurgling
Give some causes of abnormal respiratory noises heard at exercise
RLN (recurrent laryngeal neuropathy) DDSP Epiglottic entrapment Subepiglottic cyst Epiglottic retroversion 4-BAD (fourth branchial arch defect) Alar fold collapse/ nasal paralysis ADAF (axial deviation of the aryepiglottic folds)
Which structures you examine with an endoscopy when investigating abnormal respiratory noises?
Nasal passages Sinus drainage angles Ethmoturbinates Nasopharynx Larynx Gutteral pouches
What is the only way of identifying causes of URT obstruction that only occur at exercise?
Exercise endoscopy (High speed treadmill endoscopy= gold standard Can also use dynamic respiratory endoscope-attaches to bridle)
How can you tell if a nasal obstruction is present above or below the nasal septum?
Rostral to nasal septum=unilateral discharge
Above nasal septum=bilateral discharge
When doing radiography, the latero-lateral view is good for assessing which structures?
Paranasal sinuses, gutteral pouches and pharynx
When doing radiography, lateral oblique views are good for assessing which structures?
Peri-apical regions of the premolars and molars (prevents superimposition)
When doing radiography, the dorso-ventral view is good for assessing which structures?
Paranasal sinuses, nasal septum and teeth
Helps to decode of lesions are unilateral or bilateral
Why might you perform a sinoscopy?
Investigate suspected paranasal sinus disease
Obtain material for biopsy
Treatment
Which diagnostic techniques might you use to investigate suspected masses?
MRI
CT scan
What is scintigraphy?
Radio isotopes are administered IV
The emitted radiation is measured by external detectors to produce 2D images
When might you use scintigraphy?
Investigation of orthopaedic disease (eg fracture identification)
Suspected TMJ disease
Identification of damaged tooth
Differentiation between primary and secondary sinusitis
How can you investigate alar folds collapse?
Temporary suture across bridge of nose, if resolves, alar folds collapse is cause of problem
Which bone separates the left and right nasal passages?
Nasal septum and vomer bone
The nasal passages are divided into which 3 sections?
Dorsal, middle, ventral meatus
What are the clinical signs of a problem with the nasal passages?
Nasal discharge Halitosis Abnormal respiratory noise Coughing Facial distortion Head shaking
How can you diagnose problems with the nasal passages?
Radiography
Ultrasound
CT scan
What is wry nose?
Congenital shortening of maxilla, nasal and vomer bones
Causes laterally deviated rostral maxilla and associated nasal septum deviation
Nasal obstruction
Usually accompanied by malocclusion of the teeth
Give some causes of disease in the nasal passages
Trauma Wry nose Deviation or thickening of the nasal septum Neoplasia (carcinoma) Progressive ethmoidal haematoma Fungal infection
When placing an nasogastric tube, which meatus should it pass through?
Ventral (less likely to damage ethmoturbinates)
Use lubricant on end of tube, don’t force it when you hit resistance
What is an ethmoid haematoma?
Encapsulated non-neoplastic mass
Grows into the nasal passages/paranasal sinuses
Unknown aetiology
What are the clinical signs of an ethmoid haematoma?
Mild intermittent unilateral epistaxis
Occasionally abnormal resp noise at exercise
+/- bad smell
How can you diagnose an ethmoid haematoma?
Endoscopy +/- radiography
CT scan
How do you treat an ethmoid haematoma?
Lesions in the nasal passages can be treated with intra-lesional formalin (causes aggressive necrosis of haematoma), however there is potential damage to sinus lining
Laser removal
Surgical removal
Recurrence common
What are the clinical signs of fungal rhinitis (nasal aspergillosis)?
How do you diagnose and treat it?
Unilateral purulent/ occasionally haemorrhagic nasal discharge
Foul smell
Occasionally nasal stertor
Diagnosis: endoscopy
Treatment: removal of fungal plaques and necrotic bone Topical treatment (nystatin powder)
Name the seven pairs of paranasal sinuses
Rostral maxillary Caudal maxillary Frontal Dorsal conchal Ventral conchal Sphenopalatine Ethmoid
How does drainage of sinuses occur?
Gravity and mucociliary action
Where do the other sinuses (apart from rostral maxillary and ventral conchal sinuses) drain?
Into the caudal maxillary sinus -> Middle meatus via the nasomaxillary aperture
What are the clinical signs of paranasal sinus disease?
Unilateral/bilateral nasal discharge (serous/purulent/mucopurulent/ occasionally haemorrhagic)
+/- facial swelling
+/- decreased nasal airflow (depending on amount of secondary oedema)
Fluid lines within a sinus on a radiograph indicate what?
Sinusitis
What is the difference between primary and secondary sinusitis?
Primary: usually results from previous resp tract infection, most commonly infection by streptococcus spp
Secondary: to bother condition, primarily dental disease die to the proximity of the alveolar bone to the maxillary sinuses (08, 09, 10, 11)
How do you treat primary sinusitis?
Rule out strep equi var equi (strangles)
Place on antibiotics eg trimethoprim sulphonamides for 7-14 days
Feed from the ground to encourage drainage
Dust-free management
Turnout as much as possible
Which structure may obstruct the drainage angle of the ventral conchal sinus?
Maxillary septal bulla
How may you surgically approach the paranasal sinuses?
Trephination or bone flap
How do you treat sinusitis that is secondary to peri-apical tooth infection?
Remove affected tooth
Flush sinuses
How do you treat sinusitis that is secondary to a facial fracture?
Remove/stabilise bone fragments
Flush sinuses
Give some clinical signs associated with paranasal sinus cysts
Facial swelling
Reduced nasal airflow
Nasal discharge
Nasal stertor
How do you treat a paranasal sinus cyst?
Surgical removal
What is suturitis?
Periostitis of the suture lines between the nasal and frontal bones
Bilateral firm non-painful swellings in the nasofrontal region
Usually regress with time
What are the two main functions of the pharynx?
Deliver air from the nasal cavity to the larynx
Provides a pathway for food from the oral cavity to the oesophagus
What separates the nasopharynx from the oropharynx?
Soft palate
Why does the pharynx have the potential to collapse during exercise?
Lacks rigid support by bone/cartilage
How does the pharynx retain stability?
Coordinated neuromuscular function
Which nerves innervate the pharynx?
Mandibular branch of trigeminal
Pharyngeal branch of vagus
Hypoglossal
Cervical nerves
What are the main functions of the larynx?
Breathing (communication between pharynx and trachea)
Protect lower airway (prevent inhalation of food during swallowing)
Phonation/ vocalisation
Which cartilages make up the larynx?
Cricoid cartilage
Thyroid cartilage
Epiglottis
Paired arytenoid cartilages
Which muscle is the principle abductor of the glottis?
Cricoarytenoideus dorsalis
Which muscle is the principle adductor of the glottis?
Cricoarytenoidalis lateralis
When does the glottis open and close?
Open: exercise
Close: swallowing
Describe the slap test
Used to diagnose left recurrent laryngeal neuropathy (roaring)
Involves slapping one hemithorax to cause a reflex adduction of the muscular process of the arytenoid cartilage on the opposite side
Which diagnostic techniques can be used to examine the larynx and pharynx?
Endoscopy- exercise and at rest
Radiography
Ultrasound
Give some clinical signs associated with problems with the pharynx
Poor performance Respiratory noise Dysphagia (difficulty swallowing) Nasal discharge Coughing Respiratory distress
Give some diseases associated with the pharynx
Cleft palate Pharyngeal lymphoid hyperplasia DDSP (dorsal displacement of soft palate, can be persistent or intermittent) Palatal instability Pharyngeal collapse Pharyngeal mass Foreign body
When does intermittent dorsal displacement of the soft palate tend to occur?
What happens?
Intense exercise
Soft palate displaces dorsally resulting in an expiratory obstruction
Is intermittent or persistent dorsal displacement of the soft palate often secondary to other disease?
Persistent
Eg epiglottic entrapment, sub-epiglottic ulcer, sub-epiglottic cyst
Give some clinical signs of dorsal displacement of the soft palate
Exercise intolerance
Gurgling/vibrating noise
Rider reports ‘choking/swallowing its tongue’
How can you diagnose DDSP (dorsal displacement of soft palate)?
Endoscopy: resting (limited value) and during exercise (gold standard)
What is the function of thyrohyoideus?
Draws pharynx and larynx rostrally
What is a ‘tie-back’ procedure?
Operation to resolve roaring
Arytenoid cartilage is pulled to the side and sutured to keep it from interfering with airflow
What causes intermittent dorsal displacement of soft palate (IDDSP)?
Neuromuscular dysfunction:
- Pharyngeal branch of vagus nerve/Hypoglossal
- Thyrohyoideus
- Alteration in laryngohyoid position
- Inflammation
Which conservative treatment could you use to treat intermittent dorsal displacement of soft palate (IDDSP)?
Get horses fit
Change tack
Treat inflammatory conditions of the pharynx and gutteral pouch
Try throat support device?
How can you surgically treat dorsal displacement of the soft palate?
Staphylectomy: partial soft palate resection
Myectomy: removal of some of the extrinsic muscles of the larynx, reduced caudal retraction of the larynx
Induction of palatal fibrosis: thermal/laser cautery, stiffens soft palate
Tie forward: BEST, sutures placed between basihyoid bone and thyroid cartilage, positions larynx more rostrally and dorsally
How would you identify a foal with cleft palate?
Milk at nostril
What clinical signs are seen with laryngeal problems?
Respiratory noise Poor performance Dysphagia Coughing Respiratory distress
Explain recurrent laryngeal neuropathy
Common, large breeds
Unilateral paralysis of the left arytenoid cartilage
Progressive loss of myelinated nerve fibres in the left recurrent laryngeal nerve
Atrophy of cricoarytenoidalis dorsalis muscle
Loss of abductor and adductor function
How do you diagnose RLN (recurrent laryngeal neuropathy)?
Abnormal inspiratory noise at exercise - roaring
Poor performance
Clinical exam: +/- atrophy of CAD, negative result on slap test
Endoscopy at rest: asses synchrony of movement, ability to achieve and maintain full abduction (grade 1-4: Havemeyer scale)
Dynamic endoscopy is gold standard to asses degree of collapse during exercise
Describe the 4 grades of the Havemeyer scale when grading RLN (recurrent laryngeal neuropathy)
I: all arytenoid cartilage movements are synchronous and symmetrical. Full arytenoid abduction can be achieved and maintained.
II: arytenoid cartilage movements are asynchronous but full abduction can be achieved and maintained (sub-grades: 1.Transient 2.Permanent)
III. arytenoid cartilage movements are asynchronous and/or asymmetric. Full arytenoid abduction cannot be achieved and maintained (1.Occasions of symmetrical abduction 2.Obvious asymmetry 3.Marked but not total asymmetry)
IV. Complete immobility of the arytenoid cartilage and vocal fold
How can you treat RLN (recurrent laryngeal neuropathy)?
Ventriculectomy
Laryngoplasty (‘tie back’)
Describe a ventriculectomy procedure
Used to treat RLN (recurrent laryngeal neuropathy)
‘Hob day’ procedure
Roaring burr used to every left or both ventricles, which are then excised
+/- vocal cord removed at same time
Describe a ‘tie-back’ procedure
Used to treat RLN (recurrent laryngeal neuropathy)
Suture placed between dorsocaudal edge of cricoid cartilage and muscular process of arytenoid cartilage
Mimics the action of CAD (Cricoarytenoideus dorsalis)
Results in permanent abduction of left arytenoid cartilage
Give some complications of tie-back procedures
Failure Dysphagia Aspiration Persistent cough Infection
Give some causes of laryngeal paralysis (besides RLN)
Gutteral pouch disease
Peripheral neuropathy (eg liver disease)
Organophosphate poisoning
Fourth branchial arch arch defect (4BAD) affects which side of the larynx?
Right side
Explain fourth branchial arch defect
Variable development of the right laryngeal cartilage
Right-sided asymmetry
Rostral displacement of palatopharyngeal arch
Variable ability to abduct right arytenoid cartilage
What is vocal cord collapse (VCC) associated with?
ADAF
Axial deviation of aryepiglottic folds
Describe arytenoid chondritis
Mucosal ulceration
Infection of arytenoid cartilage
Progressive
Respiratory obstruction (younger TB, older mares)
What are the gutteral pouches?
Air-filled mucosa-lined outpouchings of the auditory tubes connecting the nasopharynx to the middle ear
Present in horses but no other domestic species
Paired
350ml in volume
Which structures border the gutteral pouches?
Dorsal: base of skull, first cervical vertebra, tympanic bulla, auditory meatus
Medial: median septum, rectus and longus capitis muscles
Ventral: nasopharynx, retropharyngeal lymph nodes
Lateral: parotid and mandibular salivary glands, Pterygoid muscles
How are gutteral pouches separated?
Separated into a medial and lateral compartment by the stylohyoid bone
Medial is bigger than lateral
Where do gutteral pouches empty?
Nasopharynx via a funnel-shaped orifice that has a fibrocartilage flap
Internal and external carotid arteries supply which compartment of gutteral pouches?
Internal: medial compartment
External: lateral compartment
What are the clinical signs of gutteral pouch disease?
Epistaxis Swelling/dyspnoea Nasal discharge Nerve dysfunction -dysphagia -laryngeal paralysis -Horner's syndrome (constructed pupil) -facial asymmetry
Give some diseases associated with gutteral pouches
Mycosis
Empyema/chondroids
Tympany
Otitis interna/media
Stylohyoid bone: temporohyoid osteopathy, fracture of petrous temporal/basisphenoid
Rupture of longus capitus ‘strap’ muscle
Neoplasia/cysts/foreign bodies
Describe gutteral pouch mycosis
Primary fungal plaque forms over vessels (most commonly internal carotid)
Uncommon but potentially life-threatening
What are the clinical signs of gutteral pouch mycosis?
Nasal discharge
Epistaxis
+/- nerve dysfunction: dysphagia, Horners (pupil constriction), laryngeal paralysis
How do you diagnose gutteral pouch mycosis?
Endoscopy
How do you treat gutteral pouch mycosis?
Surgical occlusion of affected artery: simple ligation (back flow from circle of Willis), or balloon catheterisation, or coil embolisation
Medical management if no history of bleeding: antifungals
Describe gutteral pouch empyema
Purulent material (chondroids) within one or both gutteral pouches
Usually in young horses
Aetiology: URT infection, irritant drugs
What are the clinical signs of gutteral pouch empyema?
Intermittent nasal discharge Parotid swelling and pain Extended head carriage Respiratory noise at rest Difficulty eating and swallowing Occasionally pharyngeal and laryngeal paresis
How do you diagnose gutteral pouch chondroids?
Radiography (increase radiodensity-whiteness- of gutteral pouches on lateral views
Endoscopy (dorsal pharyngeal compression, purulent material in gutteral pouches)
How do you treat chondroids?
Flushing of gutteral pouches using catheters inserted via sinus ostia (small openings connecting sinus to nasal pharynx)
Endoscopic removal of chondroids
Surgical flushing and removal of material
Describe gutteral pouch tympany
Foals Usually unilateral Marked retropharyngeal swelling Clinical signs of: swelling, resp stridor, dysphagia Confirmed on radiography or endoscopy
Describe temporohyoid osteoarthropathy
Progressive disease of the middle ear and bones of the temporohyoid joint (stylohyoid bone, squamous portion of temporal bone)
Aetiology: Middle or inner ear infection
What are the clinical signs of temporohyoid osteoarthropathy?
Early: head shaking, ear rubbing, behavioural chane
Chronic: facial nerve paralysis, head tilt, ataxia, nystagmus (toward affected side)
What are the ‘strap’ muscles?
Longus capitus
Rectus capitus ventralis
Rectus capitus lateralis
Why may the ‘strap’ neck muscles rupture?
Trauma
Usually due to rearing and falling over backwards
Which clinical signs are associated with rupture of the ‘strap’ muscles?
Profuse bilateral epistaxis Ataxia Head tilt Pharyngeal and tracheal compression and secondary upper airway obstruction
How do you diagnose rupture of the neck ‘strap’ muscles?
Endoscopy: roof of pharynx collapsed, normal vessels, swollen muscle bellies
Radiography: fluid lines within gutteral pouch
What is the treatment for rupture of the neck ‘strap’ muscles?
Stall rest
Dependent on degree of concurrent brain trauma or skull fracture
Anti-inflammatories
Supportive care
When is a tracheotomy carried out?
Emergency bypass of URT obstruction
Route for intubation
Rest the URT
Bypass inoperable URT obstruction
How would you perform an emergency tracheotomy?
Clip a 20 x 10cm area on ventral midline at junction between middle and upper third of neck
Palpate paired sternothyrohyoideus muscles and tracheal rings
Give 10ml LA (eg mepivacaine) into skin and underlying tissues
Aseptically prepare site
Make a 6-8cm incision on ventral midline of neck
Palpate the two tracheal rings in the centre of the incision
Make a stab incision between the two rings
Extend the incision for 1-2cm each side of the midline
Insert tracheotomy tube
Secure in place
Give some differential diagnoses for dysphagia
Oesophageal obstruction Retropharyngeal abscess (eg strangles) Retropharyngeal mass (neoplasias, granuloma) Pharyngeal foreign body Gutteral pouch mycosis Equine grass sickness URT infection
Onchocerca cervicalis are found where?
Nuchal ligament
nematode
How big are pinworms?
2-13mm
What is the proper name for pinworm?
Oxyuris equi
What is urticaria?
Raised itchy rash
Wheals, oedema and pruritus
Sweet itch is caused by what?
Where on the horse is it seen?
Culicoides spp
Dorsal surface of horse: tail, mane, back
What does atopy mean?
Hyperallergic
How do you diagnose atopy?
Intradermal skin testing
What is the difference between scaling and crusting?
Scaling= dry, grey Crusting= yellow, red, brown, wet/damp
What is the difference between erosion and ulceration?
Erosion is superficial (partial loss of epithelial or mucosal surface that heals by resolution)
Ulceration is deeper (full thickness loss of epithelial or mucosal surface which heals by repair ie replacement with fibrous tissue)
Describe pemphigus foliaceus
Rare, autoimmune, horse makes antibodies against its own skin Severe crusting No age or sex predilection Dx: skin biopsy Tx: immunosuppressive drugs Prognosis: guarded
Viral papillomas are seen where?
Muzzle, face, pinna, inguinal area
Describe dermatophilosis congolensis
Gram +, facultative anaerobe, branching filaments on histology
Favourable conditions= skin trauma, wet skin
Thick, parakeratotic crusts (continuous epidermal invasion)
Tx: topical (mild cases), systemic antimicrobials (severe cases)
Bacterial folliculitis is caused by what?
Staphylococcus and streptococcus
Give an antifungal used to treat ringworm?
Miconazole
Describe leukocytoclastic vasculitis
Common, affects non-pigmented areas on distal limb
Results from deposition of immune complexes at vessel wall
Painful
Dx: skin biopsy
Tx: corticosteroids, avoid exposure to light
Describe pastern dermatitis
‘Greasy heel’ syndrome
Very common
Caused by chronic wetting of skin on distal heel
Winter, white limbs
What are warbles?
Larval stages of Hypoderma bovis and lineatum, appear as nodule with a central pore (larvae inside)
Neck and trunk
Often painful
Tx: enlargement of pore to remove central grub
What is an atheroma?
Degeneration of the walls of the arteries caused by accumulated fatty deposits and scar tissue
Leads to restriction of circulation -> thrombosis
What types of skin tumours are present in horses?
Sarcoids
Melanoma
Squamous cell carcinoma
Mast cell tumour
Describe sarcoids
Most common skin tumour in horses
Tumour of fibroblasts
Bovine papillomavirus 1 and 2 are most likely cause
6 clinical presentations: occult, verrucous, nodular, fibroblastic, mixed, malignant
Dx: biopsy
Tx: surgery, immune therapy, cytotoxics,
Where are melanomas usually seen?
Perineum, tail head (near anus), parotid region
How do you treat a melanoma?
Surgical excision, immunotherapy
Where are squamous cell carcinomas usually seen?
Poorly pigmented animals
External genitalia, eyes
Where are mast cell rumours found?
Head
Solitary
Males
How is equine herpes virus spread?
Mainly be respiratory route
Aborted foetus/ membranes/ vaginal discharge are highly contagious
How do large and small strongyles affect the colon?
Large: verminous arteritis, thromboembolic colic
Small: submucosal inflammation
Give some haematological changes associated with parasitism?
Neutrophilia, hypoalbuminaemia, hyperglobulinaemia
NOT eosinophilia
What are the two divisions of equine gastric ulcer syndrome?
Give possible risk factors for each
EGGUS: Equine glandular gastric ulcer syndrome (bother horses mοre, harder to treat). Risk factors= possibly stress, NSAID-related.
ESGUS: Equine squamous gastric ulcer syndrome. Risk factor= acid injury.
What are the signs of EGUS (equine gastric ulcer syndrome)?
Weight loss, poor performance
Selective appetite, slow eating, prefer roughage over grain
Bad/cranky behaviou
Colic very unlikely
What is the pH in the two parts of the stomach?
Squamous portion prone to acid injury: pH 5.4
Glandular, acid-secreting portion protected from acid injury by mucous layer: 1.8
Where do ESGUS and EGGUS usually occur?
ESGUS: Caused by ‘splashing’ of stomach acid onto the unprotected mucosal lining above the margo plicatus, on squamous portion of stomach
EGGUS: below margo plicatus on glandular portion of stomach, when protective lining breaks down, exposing the mucosa to acids
Why is the horse so susceptible to gastric ulcers?
Stomach anatomy -> poor mixing of food, grain portion is rapidly fermentable -> acid production
Give some predisposing factors to acid injury leading to gastric ulcers
High concentrate diets -> volatile fatty acids and indirect acid injury via gastrin production in response to absorbed CHO (carbohydrates)
Also, low fibre concentrations -> reduced saliva production (saliva is an acid buffer)
Exercise -> gastrin production, also increased abdominal pressure can promote ‘splashing’ of acid onto unprotected squamous portion
How do you diagnose gastric ulcers?
Gastroscopy - 3m endoscope
Why is a faecal occult blood test not reliable for diagnosing gastric ulcers?
False negatives
How do you treat gastric ulcers?
Omeprazole (proton pump inhibitor)
- Buffered
- Enteric coated
- Plain
EGGUS requires higher doses
Give some clinical signs of colic in order of increasing severity
Flank watching Lying down Pawing the ground Rolling Repeatedly getting up and down Violent thrashing around
Give the different classifications of colic
Spasmodic Impactions Gas distension Obstructions (simple/ strangulating) Non-strangulating infarction Inflammation (enteritis/ colitis) Idiopathic
How do severe cases of colic lead to shock?
Loss of vascular supply to mucosa
Absorption of endotoxins into the circulation
Systemic inflammatory response system (SIRS)
What percentage of colic cases require surgery?
7%
What initial advice should you give to an owner of a horse with suspected colic?
Put horse in a well bedded stable
Remove anything it could injure itself on (buckets, feed etc)
Let horse roll if it wants to
A short period (10 mins) of walking exercise is fine but nothing longer before seeing a vet
Which sedative should you give to a horse with colic when examining it?
Xylazine iv (200mg for a 500kg horse) Also gives analgesia
Which questions should you ask a horse owner when investigating colic?
Which signs were observed?
When did these start/ when was the horse last normal?
Feed intake and faecal output over last 24 hours
Any diarrhoea?
History of equine grass sickness on premises?
Which structures are identifiable during a rectal palpation?
Pelvic flexure Caecum Spleen Nephrosplenic space Small (descending) colon Inguinal rings
What are some common findings when doing a rectal exam to investigate colic?
Distended SI Pelvic flexure impaction Left dorsal displacement Right dorsal displacement Large colon torsion Caecal impaction Small colon impaction
What sized needle should you use when doing an abdominocentesis?
18g, 1.5 inch
What is the appearance of normal peritoneal fluid?
Clear, straw-coloured
Regarding peritoneal fluid, what are the normal values for:
Total protein
WBCC
Lactate
Total protein:
What is the normal packed cell volume of a horse?
35-45%
What is the normal value for systemic total protein?
60-70g/L
Which diagnostic tests should you do when investigating colic?
Haematology (systemic lactate, WBC, systemic TP) Rectal exam Abdominocentesis Nasogastric intubation Ultrasound
What is the most common cause of colic in the foal?
Meconium impaction
What is the medical term for equine grass sickness?
Equine dysautonomia
What is the suspected cause of equine grass sickness?
Clostridium botulinum type C (exists in soil)
Acute, subacute, and chronic forms
Affects autonomic nervous system -> reduced GI motility
Causes a paralytic ileus (obstruction of ileum)
Patchy sweating, tachycardia
Fatal
What are the functions of the upper airways?
Channel for conveying airflow to and from lung
Filtering and conditioning of inspired air
Protection of lower airway from aspiration
Olfaction
Phonation
Swallowing
Thermoregulation
Why is a normal upper airway so critical in a horse in particular?
Because the horse is an obligate nasal breather
What is the tidal volume of a horse at rest?
5L
What is meant by tidal volume?
Lung volume, representing the normal volume of air displaced between normal inhalation and exhalation
What is the minute ventilation of a horse at rest and during exercise?
Rest: 75L
Exercise: 1500L (20x increase)
How do you work out minute ventilation?
Tidal volume x resp rate
Give some clinical signs of upper airway disease
Nasal discharge
Respiratory distress
Exercise intolerance
Noise at exercise
When investigating URT disease, what should you look out for regarding nasal discharge?
Is it unilateral/bilateral? Chronicity Nature of discharge (blood/purulent/serous/food material) Recent head trauma? Recent URT infection? Is it associated with exercise? Any cough/ resp noise? Any facial swelling? Any response to treatment?
When investigating URT disease, what should you look out for regarding respiratory noise?
When does it occur (rest/ exercise?)
If it occurs at exercise, what pace does it occur at?
Is the noise inspiratory/ expiratory/ both?
What does it sound like? (Whistle, roar, gurgle, snoring)
Continuous/ intermittent?
If at exercise, does the horse stop/ slow down when it occurs?
Does the noise disappear once the horse’s speed reduces?
Does the noise limit the horse’s performance?
Does the horse recover normally after exercise?
When doing a clinical exam of the head, what should you look for?
Symmetry Nasal/ocular discharge Airflow from both nostrils Percussion of sinuses Palpation of larynx Evidence of previous surgical scars
In RLN (recurrent laryngeal neuropathy- roaring), which Cricoarytenoideus dorsalis muscle is atrophied?
Left
How can you determine whether a noise made at exercise is made during inspiration or expiration?
Expiration occurs as the leading leg hits the ground at canter and gallop
Is ‘roaring’ heard during inspiration or expiration?
Inspiration
Does dorsal displacement of the soft palate causes respiratory noises during inspiration or expiration?
Both:
Expiration= loud
Inspiration= soft gurgling
Give some causes of abnormal respiratory noises heard at exercise
RLN (recurrent laryngeal neuropathy) DDSP Epiglottic entrapment Subepiglottic cyst Epiglottic retroversion 4-BAD (fourth branchial arch defect) Alar fold collapse/ nasal paralysis ADAF (axial deviation of the aryepiglottic folds)
Which structures you examine with an endoscopy when investigating abnormal respiratory noises?
Nasal passages Sinus drainage angles Ethmoturbinates Nasopharynx Larynx Gutteral pouches
What is the only way of identifying causes of URT obstruction that only occur at exercise?
Exercise endoscopy (High speed treadmill endoscopy= gold standard Can also use dynamic respiratory endoscope-attaches to bridle)
How can you tell if a nasal obstruction is present above or below the nasal septum?
Rostral to nasal septum=unilateral discharge
Above nasal septum=bilateral discharge
When doing radiography, the latero-lateral view is good for assessing which structures?
Paranasal sinuses, gutteral pouches and pharynx
When doing radiography, lateral oblique views are good for assessing which structures?
Peri-apical regions of the premolars and molars (prevents superimposition)
When doing radiography, the dorso-ventral view is good for assessing which structures?
Paranasal sinuses, nasal septum and teeth
Helps to decode of lesions are unilateral or bilateral
Why might you perform a sinoscopy?
Investigate suspected paranasal sinus disease
Obtain material for biopsy
Treatment
Which diagnostic techniques might you use to investigate suspected masses?
MRI
CT scan
What is scintigraphy?
Radio isotopes are administered IV
The emitted radiation is measured by external detectors to produce 2D images
When might you use scintigraphy?
Investigation of orthopaedic disease (eg fracture identification)
Suspected TMJ disease
Identification of damaged tooth
Differentiation between primary and secondary sinusitis
How can you investigate alar folds collapse?
Temporary suture across bridge of nose, if resolves, alar folds collapse is cause of problem
Which bone separates the left and right nasal passages?
Nasal septum and vomer bone
The nasal passages are divided into which 3 sections?
Dorsal, middle, ventral meatus
What are the clinical signs of a problem with the nasal passages?
Nasal discharge Halitosis Abnormal respiratory noise Coughing Facial distortion Head shaking
How can you diagnose problems with the nasal passages?
Radiography
Ultrasound
CT scan
What is wry nose?
Congenital shortening of maxilla, nasal and vomer bones
Causes laterally deviated rostral maxilla and associated nasal septum deviation
Nasal obstruction
Usually accompanied by malocclusion of the teeth
Give some causes of disease in the nasal passages
Trauma Wry nose Deviation or thickening of the nasal septum Neoplasia (carcinoma) Progressive ethmoidal haematoma Fungal infection
When placing an nasogastric tube, which meatus should it pass through?
Ventral (less likely to damage ethmoturbinates)
Use lubricant on end of tube, don’t force it when you hit resistance
What is an ethmoid haematoma?
Encapsulated non-neoplastic mass
Grows into the nasal passages/paranasal sinuses
Unknown aetiology
What are the clinical signs of an ethmoid haematoma?
Mild intermittent unilateral epistaxis
Occasionally abnormal resp noise at exercise
+/- bad smell
How can you diagnose an ethmoid haematoma?
Endoscopy +/- radiography
CT scan
How do you treat an ethmoid haematoma?
Lesions in the nasal passages can be treated with intra-lesional formalin (causes aggressive necrosis of haematoma), however there is potential damage to sinus lining
Laser removal
Surgical removal
Recurrence common
What are the clinical signs of fungal rhinitis (nasal aspergillosis)?
How do you diagnose and treat it?
Unilateral purulent/ occasionally haemorrhagic nasal discharge
Foul smell
Occasionally nasal stertor
Diagnosis: endoscopy
Treatment: removal of fungal plaques and necrotic bone Topical treatment (nystatin powder)
Name the seven pairs of paranasal sinuses
Rostral maxillary Caudal maxillary Frontal Dorsal conchal Ventral conchal Sphenopalatine Ethmoid
How does drainage of sinuses occur?
Gravity and mucociliary action
Where do the other sinuses (apart from rostral maxillary and ventral conchal sinuses) drain?
Into the caudal maxillary sinus -> Middle meatus via the nasomaxillary aperture
What are the clinical signs of paranasal sinus disease?
Unilateral/bilateral nasal discharge (serous/purulent/mucopurulent/ occasionally haemorrhagic)
+/- facial swelling
+/- decreased nasal airflow (depending on amount of secondary oedema)
Fluid lines within a sinus on a radiograph indicate what?
Sinusitis
What is the difference between primary and secondary sinusitis?
Primary: usually results from previous resp tract infection, most commonly infection by streptococcus spp
Secondary: to bother condition, primarily dental disease die to the proximity of the alveolar bone to the maxillary sinuses (08, 09, 10, 11)
How do you treat primary sinusitis?
Rule out strep equi var equi (strangles)
Place on antibiotics eg trimethoprim sulphonamides for 7-14 days
Feed from the ground to encourage drainage
Dust-free management
Turnout as much as possible
Which structure may obstruct the drainage angle of the ventral conchal sinus?
Maxillary septal bulla
How may you surgically approach the paranasal sinuses?
Trephination or bone flap
How do you treat sinusitis that is secondary to peri-apical tooth infection?
Remove affected tooth
Flush sinuses
How do you treat sinusitis that is secondary to a facial fracture?
Remove/stabilise bone fragments
Flush sinuses
Give some clinical signs associated with paranasal sinus cysts
Facial swelling
Reduced nasal airflow
Nasal discharge
Nasal stertor
How do you treat a paranasal sinus cyst?
Surgical removal
What is suturitis?
Periostitis of the suture lines between the nasal and frontal bones
Bilateral firm non-painful swellings in the nasofrontal region
Usually regress with time
What are the two main functions of the pharynx?
Deliver air from the nasal cavity to the larynx
Provides a pathway for food from the oral cavity to the oesophagus
What separates the nasopharynx from the oropharynx?
Soft palate
Why does the pharynx have the potential to collapse during exercise?
Lacks rigid support by bone/cartilage
How does the pharynx retain stability?
Coordinated neuromuscular function
Which nerves innervate the pharynx?
Mandibular branch of trigeminal
Pharyngeal branch of vagus
Hypoglossal
Cervical nerves
What are the main functions of the larynx?
Breathing (communication between pharynx and trachea)
Protect lower airway (prevent inhalation of food during swallowing)
Phonation/ vocalisation
Which cartilages make up the larynx?
Cricoid cartilage
Thyroid cartilage
Epiglottis
Paired arytenoid cartilages
Which muscle is the principle abductor of the glottis?
Cricoarytenoideus dorsalis
Which muscle is the principle adductor of the glottis?
Cricoarytenoidalis lateralis
When does the glottis open and close?
Open: exercise
Close: swallowing
Describe the slap test
Used to diagnose left recurrent laryngeal neuropathy (roaring)
Involves slapping one hemithorax to cause a reflex adduction of the muscular process of the arytenoid cartilage on the opposite side
Which diagnostic techniques can be used to examine the larynx and pharynx?
Endoscopy- exercise and at rest
Radiography
Ultrasound
Give some clinical signs associated with problems with the pharynx
Poor performance Respiratory noise Dysphagia (difficulty swallowing) Nasal discharge Coughing Respiratory distress
Give some diseases associated with the pharynx
Cleft palate Pharyngeal lymphoid hyperplasia DDSP (dorsal displacement of soft palate, can be persistent or intermittent) Palatal instability Pharyngeal collapse Pharyngeal mass Foreign body
When does intermittent dorsal displacement of the soft palate tend to occur?
What happens?
Intense exercise
Soft palate displaces dorsally resulting in an expiratory obstruction
Is intermittent or persistent dorsal displacement of the soft palate often secondary to other disease?
Persistent
Eg epiglottic entrapment, sub-epiglottic ulcer, sub-epiglottic cyst
Give some clinical signs of dorsal displacement of the soft palate
Exercise intolerance
Gurgling/vibrating noise
Rider reports ‘choking/swallowing its tongue’
How can you diagnose DDSP (dorsal displacement of soft palate)?
Endoscopy: resting (limited value) and during exercise (gold standard)
What is the function of thyrohyoideus?
Draws pharynx and larynx rostrally
What is a ‘tie-back’ procedure?
Operation to resolve roaring
Arytenoid cartilage is pulled to the side and sutured to keep it from interfering with airflow
What causes intermittent dorsal displacement of soft palate (IDDSP)?
Neuromuscular dysfunction:
- Pharyngeal branch of vagus nerve/Hypoglossal
- Thyrohyoideus
- Alteration in laryngohyoid position
- Inflammation
Which conservative treatment could you use to treat intermittent dorsal displacement of soft palate (IDDSP)?
Get horses fit
Change tack
Treat inflammatory conditions of the pharynx and gutteral pouch
Try throat support device?
How can you surgically treat dorsal displacement of the soft palate?
Staphylectomy: partial soft palate resection
Myectomy: removal of some of the extrinsic muscles of the larynx, reduced caudal retraction of the larynx
Induction of palatal fibrosis: thermal/laser cautery, stiffens soft palate
Tie forward: BEST, sutures placed between basihyoid bone and thyroid cartilage, positions larynx more rostrally and dorsally
How would you identify a foal with cleft palate?
Milk at nostril
What clinical signs are seen with laryngeal problems?
Respiratory noise Poor performance Dysphagia Coughing Respiratory distress
Explain recurrent laryngeal neuropathy
Common, large breeds
Unilateral paralysis of the left arytenoid cartilage
Progressive loss of myelinated nerve fibres in the left recurrent laryngeal nerve
Atrophy of cricoarytenoidalis dorsalis muscle
Loss of abductor and adductor function
How do you diagnose RLN (recurrent laryngeal neuropathy)?
Abnormal inspiratory noise at exercise - roaring
Poor performance
Clinical exam: +/- atrophy of CAD, negative result on slap test
Endoscopy at rest: asses synchrony of movement, ability to achieve and maintain full abduction (grade 1-4: Havemeyer scale)
Dynamic endoscopy is gold standard to asses degree of collapse during exercise
Describe the 4 grades of the Havemeyer scale when grading RLN (recurrent laryngeal neuropathy)
I: all arytenoid cartilage movements are synchronous and symmetrical. Full arytenoid abduction can be achieved and maintained.
II: arytenoid cartilage movements are asynchronous but full abduction can be achieved and maintained (sub-grades: 1.Transient 2.Permanent)
III. arytenoid cartilage movements are asynchronous and/or asymmetric. Full arytenoid abduction cannot be achieved and maintained (1.Occasions of symmetrical abduction 2.Obvious asymmetry 3.Marked but not total asymmetry)
IV. Complete immobility of the arytenoid cartilage and vocal fold
How can you treat RLN (recurrent laryngeal neuropathy)?
Ventriculectomy
Laryngoplasty (‘tie back’)
Describe a ventriculectomy procedure
Used to treat RLN (recurrent laryngeal neuropathy)
‘Hob day’ procedure
Roaring burr used to every left or both ventricles, which are then excised
+/- vocal cord removed at same time
Describe a ‘tie-back’ procedure
Used to treat RLN (recurrent laryngeal neuropathy)
Suture placed between dorsocaudal edge of cricoid cartilage and muscular process of arytenoid cartilage
Mimics the action of CAD (Cricoarytenoideus dorsalis)
Results in permanent abduction of left arytenoid cartilage
Give some complications of tie-back procedures
Failure Dysphagia Aspiration Persistent cough Infection
Give some causes of laryngeal paralysis (besides RLN)
Gutteral pouch disease
Peripheral neuropathy (eg liver disease)
Organophosphate poisoning
Fourth branchial arch arch defect (4BAD) affects which side of the larynx?
Right side
Explain fourth branchial arch defect
Variable development of the right laryngeal cartilage
Right-sided asymmetry
Rostral displacement of palatopharyngeal arch
Variable ability to abduct right arytenoid cartilage
What is vocal cord collapse (VCC) associated with?
ADAF
Axial deviation of aryepiglottic folds
Describe arytenoid chondritis
Mucosal ulceration
Infection of arytenoid cartilage
Progressive
Respiratory obstruction (younger TB, older mares)
What are the gutteral pouches?
Air-filled mucosa-lined outpouchings of the auditory tubes connecting the nasopharynx to the middle ear
Present in horses but no other domestic species
Paired
350ml in volume
Which structures border the gutteral pouches?
Dorsal: base of skull, first cervical vertebra, tympanic bulla, auditory meatus
Medial: median septum, rectus and longus capitis muscles
Ventral: nasopharynx, retropharyngeal lymph nodes
Lateral: parotid and mandibular salivary glands, Pterygoid muscles
How are gutteral pouches separated?
Separated into a medial and lateral compartment by the stylohyoid bone
Medial is bigger than lateral
Where do gutteral pouches empty?
Nasopharynx via a funnel-shaped orifice that has a fibrocartilage flap
Internal and external carotid arteries supply which compartment of gutteral pouches?
Internal: medial compartment
External: lateral compartment
What are the clinical signs of gutteral pouch disease?
Epistaxis Swelling/dyspnoea Nasal discharge Nerve dysfunction -dysphagia -laryngeal paralysis -Horner's syndrome (constructed pupil) -facial asymmetry
Give some diseases associated with gutteral pouches
Mycosis
Empyema/chondroids
Tympany
Otitis interna/media
Stylohyoid bone: temporohyoid osteopathy, fracture of petrous temporal/basisphenoid
Rupture of longus capitus ‘strap’ muscle
Neoplasia/cysts/foreign bodies
Describe gutteral pouch mycosis
Primary fungal plaque forms over vessels (most commonly internal carotid)
Uncommon but potentially life-threatening
What are the clinical signs of gutteral pouch mycosis?
Nasal discharge
Epistaxis
+/- nerve dysfunction: dysphagia, Horners (pupil constriction), laryngeal paralysis
How do you diagnose gutteral pouch mycosis?
Endoscopy
How do you treat gutteral pouch mycosis?
Surgical occlusion of affected artery: simple ligation (back flow from circle of Willis), or balloon catheterisation, or coil embolisation
Medical management if no history of bleeding: antifungals
Describe gutteral pouch empyema
Purulent material (chondroids) within one or both gutteral pouches
Usually in young horses
Aetiology: URT infection, irritant drugs
What are the clinical signs of gutteral pouch empyema?
Intermittent nasal discharge Parotid swelling and pain Extended head carriage Respiratory noise at rest Difficulty eating and swallowing Occasionally pharyngeal and laryngeal paresis
How do you diagnose gutteral pouch chondroids?
Radiography (increase radiodensity-whiteness- of gutteral pouches on lateral views
Endoscopy (dorsal pharyngeal compression, purulent material in gutteral pouches)
How do you treat chondroids?
Flushing of gutteral pouches using catheters inserted via sinus ostia (small openings connecting sinus to nasal pharynx)
Endoscopic removal of chondroids
Surgical flushing and removal of material
Describe gutteral pouch tympany
Foals Usually unilateral Marked retropharyngeal swelling Clinical signs of: swelling, resp stridor, dysphagia Confirmed on radiography or endoscopy
Describe temporohyoid osteoarthropathy
Progressive disease of the middle ear and bones of the temporohyoid joint (stylohyoid bone, squamous portion of temporal bone)
Aetiology: Middle or inner ear infection
What are the clinical signs of temporohyoid osteoarthropathy?
Early: head shaking, ear rubbing, behavioural chane
Chronic: facial nerve paralysis, head tilt, ataxia, nystagmus (toward affected side)
What are the ‘strap’ muscles?
Longus capitus
Rectus capitus ventralis
Rectus capitus lateralis
Why may the ‘strap’ neck muscles rupture?
Trauma
Usually due to rearing and falling over backwards
Which clinical signs are associated with rupture of the ‘strap’ muscles?
Profuse bilateral epistaxis Ataxia Head tilt Pharyngeal and tracheal compression and secondary upper airway obstruction
How do you diagnose rupture of the neck ‘strap’ muscles?
Endoscopy: roof of pharynx collapsed, normal vessels, swollen muscle bellies
Radiography: fluid lines within gutteral pouch
What is the treatment for rupture of the neck ‘strap’ muscles?
Stall rest
Dependent on degree of concurrent brain trauma or skull fracture
Anti-inflammatories
Supportive care
When is a tracheotomy carried out?
Emergency bypass of URT obstruction
Route for intubation
Rest the URT
Bypass inoperable URT obstruction
How would you perform an emergency tracheotomy?
Clip a 20 x 10cm area on ventral midline at junction between middle and upper third of neck
Palpate paired sternothyrohyoideus muscles and tracheal rings
Give 10ml LA (eg mepivacaine) into skin and underlying tissues
Aseptically prepare site
Make a 6-8cm incision on ventral midline of neck
Palpate the two tracheal rings in the centre of the incision
Make a stab incision between the two rings
Extend the incision for 1-2cm each side of the midline
Insert tracheotomy tube
Secure in place
Give some differential diagnoses for dysphagia
Oesophageal obstruction Retropharyngeal abscess (eg strangles) Retropharyngeal mass (neoplasias, granuloma) Pharyngeal foreign body Gutteral pouch mycosis Equine grass sickness URT infection
Onchocerca cervicalis are found where?
Nuchal ligament
nematode
How big are pinworms?
2-13mm
What is the proper name for pinworm?
Oxyuris equi
What is urticaria?
Raised itchy rash
Wheals, oedema and pruritus
Sweet itch is caused by what?
Where on the horse is it seen?
Culicoides spp
Dorsal surface of horse: tail, mane, back
What does atopy mean?
Hyperallergic
How do you diagnose atopy?
Intradermal skin testing
What is the difference between scaling and crusting?
Scaling= dry, grey Crusting= yellow, red, brown, wet/damp
What is the difference between erosion and ulceration?
Erosion is superficial (partial loss of epithelial or mucosal surface that heals by resolution)
Ulceration is deeper (full thickness loss of epithelial or mucosal surface which heals by repair ie replacement with fibrous tissue)
Describe pemphigus foliaceus
Rare, autoimmune, horse makes antibodies against its own skin Severe crusting No age or sex predilection Dx: skin biopsy Tx: immunosuppressive drugs Prognosis: guarded
Viral papillomas are seen where?
Muzzle, face, pinna, inguinal area
Describe dermatophilosis congolensis
Gram +, facultative anaerobe, branching filaments on histology
Favourable conditions= skin trauma, wet skin
Thick, parakeratotic crusts (continuous epidermal invasion)
Tx: topical (mild cases), systemic antimicrobials (severe cases)
Bacterial folliculitis is caused by what?
Staphylococcus and streptococcus
Give an antifungal used to treat ringworm?
Miconazole
Describe leukocytoclastic vasculitis
Common, affects non-pigmented areas on distal limb
Results from deposition of immune complexes at vessel wall
Painful
Dx: skin biopsy
Tx: corticosteroids, avoid exposure to light
Describe pastern dermatitis
‘Greasy heel’ syndrome
Very common
Caused by chronic wetting of skin on distal heel
Winter, white limbs
What are warbles?
Larval stages of Hypoderma bovis and lineatum, appear as nodule with a central pore (larvae inside)
Neck and trunk
Often painful
Tx: enlargement of pore to remove central grub
What is an atheroma?
Degeneration of the walls of the arteries caused by accumulated fatty deposits and scar tissue
Leads to restriction of circulation -> thrombosis
What types of skin tumours are present in horses?
Sarcoids
Melanoma
Squamous cell carcinoma
Mast cell tumour
Describe sarcoids
Most common skin tumour in horses
Tumour of fibroblasts
Bovine papillomavirus 1 and 2 are most likely cause
6 clinical presentations: occult, verrucous, nodular, fibroblastic, mixed, malignant
Dx: biopsy
Tx: surgery, immune therapy, cytotoxics,
Where are melanomas usually seen?
Perineum, tail head (near anus), parotid region
How do you treat a melanoma?
Surgical excision, immunotherapy
Where are squamous cell carcinomas usually seen?
Poorly pigmented animals
External genitalia, eyes
Where are mast cell rumours found?
Head
Solitary
Males
How is equine herpes virus spread?
Mainly be respiratory route
Aborted foetus/ membranes/ vaginal discharge are highly contagious
How do large and small strongyles affect the colon?
Large: verminous arteritis, thromboembolic colic
Small: submucosal inflammation
Give some haematological changes associated with parasitism?
Neutrophilia, hypoalbuminaemia, hyperglobulinaemia
NOT eosinophilia
What are the two divisions of equine gastric ulcer syndrome?
Give possible risk factors for each
EGGUS: Equine glandular gastric ulcer syndrome (bother horses mοre, harder to treat). Risk factors= possibly stress, NSAID-related.
ESGUS: Equine squamous gastric ulcer syndrome. Risk factor= acid injury.
What are the signs of EGUS (equine gastric ulcer syndrome)?
Weight loss, poor performance
Selective appetite, slow eating, prefer roughage over grain
Bad/cranky behaviou
Colic very unlikely
What is the pH in the two parts of the stomach?
Squamous portion prone to acid injury: pH 5.4
Glandular, acid-secreting portion protected from acid injury by mucous layer: 1.8
Where do ESGUS and EGGUS usually occur?
ESGUS: Caused by ‘splashing’ of stomach acid onto the unprotected mucosal lining above the margo plicatus, on squamous portion of stomach
EGGUS: below margo plicatus on glandular portion of stomach, when protective lining breaks down, exposing the mucosa to acids
Why is the horse so susceptible to gastric ulcers?
Stomach anatomy -> poor mixing of food, grain portion is rapidly fermentable -> acid production
Give some predisposing factors to acid injury leading to gastric ulcers
High concentrate diets -> volatile fatty acids and indirect acid injury via gastrin production in response to absorbed CHO (carbohydrates)
Also, low fibre concentrations -> reduced saliva production (saliva is an acid buffer)
Exercise -> gastrin production, also increased abdominal pressure can promote ‘splashing’ of acid onto unprotected squamous portion
How do you diagnose gastric ulcers?
Gastroscopy - 3m endoscope
Why is a faecal occult blood test not reliable for diagnosing gastric ulcers?
False negatives
How do you treat gastric ulcers?
Omeprazole (proton pump inhibitor)
- Buffered
- Enteric coated
- Plain
EGGUS requires higher doses
Give some clinical signs of colic in order of increasing severity
Flank watching Lying down Pawing the ground Rolling Repeatedly getting up and down Violent thrashing around
Give the different classifications of colic
Spasmodic Impactions Gas distension Obstructions (simple/ strangulating) Non-strangulating infarction Inflammation (enteritis/ colitis) Idiopathic
How do severe cases of colic lead to shock?
Loss of vascular supply to mucosa
Absorption of endotoxins into the circulation
Systemic inflammatory response system (SIRS)
What percentage of colic cases require surgery?
7%
What initial advice should you give to an owner of a horse with suspected colic?
Put horse in a well bedded stable
Remove anything it could injure itself on (buckets, feed etc)
Let horse roll if it wants to
A short period (10 mins) of walking exercise is fine but nothing longer before seeing a vet
Which sedative should you give to a horse with colic when examining it?
Xylazine iv (200mg for a 500kg horse) Also gives analgesia
Which questions should you ask a horse owner when investigating colic?
Which signs were observed?
When did these start/ when was the horse last normal?
Feed intake and faecal output over last 24 hours
Any diarrhoea?
History of equine grass sickness on premises?
Which structures are identifiable during a rectal palpation?
Pelvic flexure Caecum Spleen Nephrosplenic space Small (descending) colon Inguinal rings
What are some common findings when doing a rectal exam to investigate colic?
Distended SI Pelvic flexure impaction Left dorsal displacement Right dorsal displacement Large colon torsion Caecal impaction Small colon impaction
What sized needle should you use when doing an abdominocentesis?
18g, 1.5 inch
What is the appearance of normal peritoneal fluid?
Clear, straw-coloured
Regarding peritoneal fluid, what are the normal values for:
Total protein
WBCC
Lactate
Total protein:
What is the normal packed cell volume of a horse?
35-45%
What is the normal value for systemic total protein?
60-70g/L
Which diagnostic tests should you do when investigating colic?
Haematology (systemic lactate, WBC, systemic TP) Rectal exam Abdominocentesis Nasogastric intubation Ultrasound
What is the most common cause of colic in the foal?
Meconium impaction
What is the medical term for equine grass sickness?
Equine dysautonomia
What is the suspected cause of equine grass sickness?
Clostridium botulinum type C (exists in soil)
Acute, subacute, and chronic forms
Affects autonomic nervous system -> reduced GI motility
Causes a paralytic ileus (obstruction of ileum)
Patchy sweating, tachycardia
Fatal
What are the functions of the upper airways?
Channel for conveying airflow to and from lung
Filtering and conditioning of inspired air
Protection of lower airway from aspiration
Olfaction
Phonation
Swallowing
Thermoregulation
Why is a normal upper airway so critical in a horse in particular?
Because the horse is an obligate nasal breather
What is the tidal volume of a horse at rest?
5L
What is meant by tidal volume?
Lung volume, representing the normal volume of air displaced between normal inhalation and exhalation
What is the minute ventilation of a horse at rest and during exercise?
Rest: 75L
Exercise: 1500L (20x increase)
How do you work out minute ventilation?
Tidal volume x resp rate
Give some clinical signs of upper airway disease
Nasal discharge
Respiratory distress
Exercise intolerance
Noise at exercise
When investigating URT disease, what should you look out for regarding nasal discharge?
Is it unilateral/bilateral? Chronicity Nature of discharge (blood/purulent/serous/food material) Recent head trauma? Recent URT infection? Is it associated with exercise? Any cough/ resp noise? Any facial swelling? Any response to treatment?
When investigating URT disease, what should you look out for regarding respiratory noise?
When does it occur (rest/ exercise?)
If it occurs at exercise, what pace does it occur at?
Is the noise inspiratory/ expiratory/ both?
What does it sound like? (Whistle, roar, gurgle, snoring)
Continuous/ intermittent?
If at exercise, does the horse stop/ slow down when it occurs?
Does the noise disappear once the horse’s speed reduces?
Does the noise limit the horse’s performance?
Does the horse recover normally after exercise?
When doing a clinical exam of the head, what should you look for?
Symmetry Nasal/ocular discharge Airflow from both nostrils Percussion of sinuses Palpation of larynx Evidence of previous surgical scars
In RLN (recurrent laryngeal neuropathy- roaring), which Cricoarytenoideus dorsalis muscle is atrophied?
Left
How can you determine whether a noise made at exercise is made during inspiration or expiration?
Expiration occurs as the leading leg hits the ground at canter and gallop
Is ‘roaring’ heard during inspiration or expiration?
Inspiration
Does dorsal displacement of the soft palate causes respiratory noises during inspiration or expiration?
Both:
Expiration= loud
Inspiration= soft gurgling
Give some causes of abnormal respiratory noises heard at exercise
RLN (recurrent laryngeal neuropathy) DDSP Epiglottic entrapment Subepiglottic cyst Epiglottic retroversion 4-BAD (fourth branchial arch defect) Alar fold collapse/ nasal paralysis ADAF (axial deviation of the aryepiglottic folds)
Which structures you examine with an endoscopy when investigating abnormal respiratory noises?
Nasal passages Sinus drainage angles Ethmoturbinates Nasopharynx Larynx Gutteral pouches
What is the only way of identifying causes of URT obstruction that only occur at exercise?
Exercise endoscopy (High speed treadmill endoscopy= gold standard Can also use dynamic respiratory endoscope-attaches to bridle)
How can you tell if a nasal obstruction is present above or below the nasal septum?
Rostral to nasal septum=unilateral discharge
Above nasal septum=bilateral discharge
When doing radiography, the latero-lateral view is good for assessing which structures?
Paranasal sinuses, gutteral pouches and pharynx
When doing radiography, lateral oblique views are good for assessing which structures?
Peri-apical regions of the premolars and molars (prevents superimposition)
When doing radiography, the dorso-ventral view is good for assessing which structures?
Paranasal sinuses, nasal septum and teeth
Helps to decode of lesions are unilateral or bilateral
Why might you perform a sinoscopy?
Investigate suspected paranasal sinus disease
Obtain material for biopsy
Treatment
Which diagnostic techniques might you use to investigate suspected masses?
MRI
CT scan
What is scintigraphy?
Radio isotopes are administered IV
The emitted radiation is measured by external detectors to produce 2D images
When might you use scintigraphy?
Investigation of orthopaedic disease (eg fracture identification)
Suspected TMJ disease
Identification of damaged tooth
Differentiation between primary and secondary sinusitis
How can you investigate alar folds collapse?
Temporary suture across bridge of nose, if resolves, alar folds collapse is cause of problem
Which bone separates the left and right nasal passages?
Nasal septum and vomer bone
The nasal passages are divided into which 3 sections?
Dorsal, middle, ventral meatus
What are the clinical signs of a problem with the nasal passages?
Nasal discharge Halitosis Abnormal respiratory noise Coughing Facial distortion Head shaking
How can you diagnose problems with the nasal passages?
Radiography
Ultrasound
CT scan
What is wry nose?
Congenital shortening of maxilla, nasal and vomer bones
Causes laterally deviated rostral maxilla and associated nasal septum deviation
Nasal obstruction
Usually accompanied by malocclusion of the teeth
Give some causes of disease in the nasal passages
Trauma Wry nose Deviation or thickening of the nasal septum Neoplasia (carcinoma) Progressive ethmoidal haematoma Fungal infection
When placing an nasogastric tube, which meatus should it pass through?
Ventral (less likely to damage ethmoturbinates)
Use lubricant on end of tube, don’t force it when you hit resistance
What is an ethmoid haematoma?
Encapsulated non-neoplastic mass
Grows into the nasal passages/paranasal sinuses
Unknown aetiology
What are the clinical signs of an ethmoid haematoma?
Mild intermittent unilateral epistaxis
Occasionally abnormal resp noise at exercise
+/- bad smell
How can you diagnose an ethmoid haematoma?
Endoscopy +/- radiography
CT scan
How do you treat an ethmoid haematoma?
Lesions in the nasal passages can be treated with intra-lesional formalin (causes aggressive necrosis of haematoma), however there is potential damage to sinus lining
Laser removal
Surgical removal
Recurrence common
What are the clinical signs of fungal rhinitis (nasal aspergillosis)?
How do you diagnose and treat it?
Unilateral purulent/ occasionally haemorrhagic nasal discharge
Foul smell
Occasionally nasal stertor
Diagnosis: endoscopy
Treatment: removal of fungal plaques and necrotic bone Topical treatment (nystatin powder)
Name the seven pairs of paranasal sinuses
Rostral maxillary Caudal maxillary Frontal Dorsal conchal Ventral conchal Sphenopalatine Ethmoid
How does drainage of sinuses occur?
Gravity and mucociliary action
Where do the other sinuses (apart from rostral maxillary and ventral conchal sinuses) drain?
Into the caudal maxillary sinus -> Middle meatus via the nasomaxillary aperture
What are the clinical signs of paranasal sinus disease?
Unilateral/bilateral nasal discharge (serous/purulent/mucopurulent/ occasionally haemorrhagic)
+/- facial swelling
+/- decreased nasal airflow (depending on amount of secondary oedema)
Fluid lines within a sinus on a radiograph indicate what?
Sinusitis
What is the difference between primary and secondary sinusitis?
Primary: usually results from previous resp tract infection, most commonly infection by streptococcus spp
Secondary: to bother condition, primarily dental disease die to the proximity of the alveolar bone to the maxillary sinuses (08, 09, 10, 11)
How do you treat primary sinusitis?
Rule out strep equi var equi (strangles)
Place on antibiotics eg trimethoprim sulphonamides for 7-14 days
Feed from the ground to encourage drainage
Dust-free management
Turnout as much as possible
Which structure may obstruct the drainage angle of the ventral conchal sinus?
Maxillary septal bulla
How may you surgically approach the paranasal sinuses?
Trephination or bone flap
How do you treat sinusitis that is secondary to peri-apical tooth infection?
Remove affected tooth
Flush sinuses
How do you treat sinusitis that is secondary to a facial fracture?
Remove/stabilise bone fragments
Flush sinuses
Give some clinical signs associated with paranasal sinus cysts
Facial swelling
Reduced nasal airflow
Nasal discharge
Nasal stertor
How do you treat a paranasal sinus cyst?
Surgical removal
What is suturitis?
Periostitis of the suture lines between the nasal and frontal bones
Bilateral firm non-painful swellings in the nasofrontal region
Usually regress with time
What are the two main functions of the pharynx?
Deliver air from the nasal cavity to the larynx
Provides a pathway for food from the oral cavity to the oesophagus
What separates the nasopharynx from the oropharynx?
Soft palate
Why does the pharynx have the potential to collapse during exercise?
Lacks rigid support by bone/cartilage
How does the pharynx retain stability?
Coordinated neuromuscular function
Which nerves innervate the pharynx?
Mandibular branch of trigeminal
Pharyngeal branch of vagus
Hypoglossal
Cervical nerves
What are the main functions of the larynx?
Breathing (communication between pharynx and trachea)
Protect lower airway (prevent inhalation of food during swallowing)
Phonation/ vocalisation
Which cartilages make up the larynx?
Cricoid cartilage
Thyroid cartilage
Epiglottis
Paired arytenoid cartilages
Which muscle is the principle abductor of the glottis?
Cricoarytenoideus dorsalis
Which muscle is the principle adductor of the glottis?
Cricoarytenoidalis lateralis
When does the glottis open and close?
Open: exercise
Close: swallowing
Describe the slap test
Used to diagnose left recurrent laryngeal neuropathy (roaring)
Involves slapping one hemithorax to cause a reflex adduction of the muscular process of the arytenoid cartilage on the opposite side
Which diagnostic techniques can be used to examine the larynx and pharynx?
Endoscopy- exercise and at rest
Radiography
Ultrasound
Give some clinical signs associated with problems with the pharynx
Poor performance Respiratory noise Dysphagia (difficulty swallowing) Nasal discharge Coughing Respiratory distress
Give some diseases associated with the pharynx
Cleft palate Pharyngeal lymphoid hyperplasia DDSP (dorsal displacement of soft palate, can be persistent or intermittent) Palatal instability Pharyngeal collapse Pharyngeal mass Foreign body
When does intermittent dorsal displacement of the soft palate tend to occur?
What happens?
Intense exercise
Soft palate displaces dorsally resulting in an expiratory obstruction
Is intermittent or persistent dorsal displacement of the soft palate often secondary to other disease?
Persistent
Eg epiglottic entrapment, sub-epiglottic ulcer, sub-epiglottic cyst
Give some clinical signs of dorsal displacement of the soft palate
Exercise intolerance
Gurgling/vibrating noise
Rider reports ‘choking/swallowing its tongue’
How can you diagnose DDSP (dorsal displacement of soft palate)?
Endoscopy: resting (limited value) and during exercise (gold standard)
What is the function of thyrohyoideus?
Draws pharynx and larynx rostrally
What is a ‘tie-back’ procedure?
Operation to resolve roaring
Arytenoid cartilage is pulled to the side and sutured to keep it from interfering with airflow
What causes intermittent dorsal displacement of soft palate (IDDSP)?
Neuromuscular dysfunction:
- Pharyngeal branch of vagus nerve/Hypoglossal
- Thyrohyoideus
- Alteration in laryngohyoid position
- Inflammation
Which conservative treatment could you use to treat intermittent dorsal displacement of soft palate (IDDSP)?
Get horses fit
Change tack
Treat inflammatory conditions of the pharynx and gutteral pouch
Try throat support device?
How can you surgically treat dorsal displacement of the soft palate?
Staphylectomy: partial soft palate resection
Myectomy: removal of some of the extrinsic muscles of the larynx, reduced caudal retraction of the larynx
Induction of palatal fibrosis: thermal/laser cautery, stiffens soft palate
Tie forward: BEST, sutures placed between basihyoid bone and thyroid cartilage, positions larynx more rostrally and dorsally
How would you identify a foal with cleft palate?
Milk at nostril
What clinical signs are seen with laryngeal problems?
Respiratory noise Poor performance Dysphagia Coughing Respiratory distress
Explain recurrent laryngeal neuropathy
Common, large breeds
Unilateral paralysis of the left arytenoid cartilage
Progressive loss of myelinated nerve fibres in the left recurrent laryngeal nerve
Atrophy of cricoarytenoidalis dorsalis muscle
Loss of abductor and adductor function
How do you diagnose RLN (recurrent laryngeal neuropathy)?
Abnormal inspiratory noise at exercise - roaring
Poor performance
Clinical exam: +/- atrophy of CAD, negative result on slap test
Endoscopy at rest: asses synchrony of movement, ability to achieve and maintain full abduction (grade 1-4: Havemeyer scale)
Dynamic endoscopy is gold standard to asses degree of collapse during exercise
Describe the 4 grades of the Havemeyer scale when grading RLN (recurrent laryngeal neuropathy)
I: all arytenoid cartilage movements are synchronous and symmetrical. Full arytenoid abduction can be achieved and maintained.
II: arytenoid cartilage movements are asynchronous but full abduction can be achieved and maintained (sub-grades: 1.Transient 2.Permanent)
III. arytenoid cartilage movements are asynchronous and/or asymmetric. Full arytenoid abduction cannot be achieved and maintained (1.Occasions of symmetrical abduction 2.Obvious asymmetry 3.Marked but not total asymmetry)
IV. Complete immobility of the arytenoid cartilage and vocal fold
How can you treat RLN (recurrent laryngeal neuropathy)?
Ventriculectomy
Laryngoplasty (‘tie back’)
Describe a ventriculectomy procedure
Used to treat RLN (recurrent laryngeal neuropathy)
‘Hob day’ procedure
Roaring burr used to every left or both ventricles, which are then excised
+/- vocal cord removed at same time
Describe a ‘tie-back’ procedure
Used to treat RLN (recurrent laryngeal neuropathy)
Suture placed between dorsocaudal edge of cricoid cartilage and muscular process of arytenoid cartilage
Mimics the action of CAD (Cricoarytenoideus dorsalis)
Results in permanent abduction of left arytenoid cartilage
Give some complications of tie-back procedures
Failure Dysphagia Aspiration Persistent cough Infection
Give some causes of laryngeal paralysis (besides RLN)
Gutteral pouch disease
Peripheral neuropathy (eg liver disease)
Organophosphate poisoning
Fourth branchial arch arch defect (4BAD) affects which side of the larynx?
Right side
Explain fourth branchial arch defect
Variable development of the right laryngeal cartilage
Right-sided asymmetry
Rostral displacement of palatopharyngeal arch
Variable ability to abduct right arytenoid cartilage
What is vocal cord collapse (VCC) associated with?
ADAF
Axial deviation of aryepiglottic folds
Describe arytenoid chondritis
Mucosal ulceration
Infection of arytenoid cartilage
Progressive
Respiratory obstruction (younger TB, older mares)
What are the gutteral pouches?
Air-filled mucosa-lined outpouchings of the auditory tubes connecting the nasopharynx to the middle ear
Present in horses but no other domestic species
Paired
350ml in volume
Which structures border the gutteral pouches?
Dorsal: base of skull, first cervical vertebra, tympanic bulla, auditory meatus
Medial: median septum, rectus and longus capitis muscles
Ventral: nasopharynx, retropharyngeal lymph nodes
Lateral: parotid and mandibular salivary glands, Pterygoid muscles
How are gutteral pouches separated?
Separated into a medial and lateral compartment by the stylohyoid bone
Medial is bigger than lateral
Where do gutteral pouches empty?
Nasopharynx via a funnel-shaped orifice that has a fibrocartilage flap
Internal and external carotid arteries supply which compartment of gutteral pouches?
Internal: medial compartment
External: lateral compartment
What are the clinical signs of gutteral pouch disease?
Epistaxis Swelling/dyspnoea Nasal discharge Nerve dysfunction -dysphagia -laryngeal paralysis -Horner's syndrome (constructed pupil) -facial asymmetry
Give some diseases associated with gutteral pouches
Mycosis
Empyema/chondroids
Tympany
Otitis interna/media
Stylohyoid bone: temporohyoid osteopathy, fracture of petrous temporal/basisphenoid
Rupture of longus capitus ‘strap’ muscle
Neoplasia/cysts/foreign bodies
Describe gutteral pouch mycosis
Primary fungal plaque forms over vessels (most commonly internal carotid)
Uncommon but potentially life-threatening
What are the clinical signs of gutteral pouch mycosis?
Nasal discharge
Epistaxis
+/- nerve dysfunction: dysphagia, Horners (pupil constriction), laryngeal paralysis
How do you diagnose gutteral pouch mycosis?
Endoscopy
How do you treat gutteral pouch mycosis?
Surgical occlusion of affected artery: simple ligation (back flow from circle of Willis), or balloon catheterisation, or coil embolisation
Medical management if no history of bleeding: antifungals
Describe gutteral pouch empyema
Purulent material (chondroids) within one or both gutteral pouches
Usually in young horses
Aetiology: URT infection, irritant drugs
What are the clinical signs of gutteral pouch empyema?
Intermittent nasal discharge Parotid swelling and pain Extended head carriage Respiratory noise at rest Difficulty eating and swallowing Occasionally pharyngeal and laryngeal paresis
How do you diagnose gutteral pouch chondroids?
Radiography (increase radiodensity-whiteness- of gutteral pouches on lateral views
Endoscopy (dorsal pharyngeal compression, purulent material in gutteral pouches)
How do you treat chondroids?
Flushing of gutteral pouches using catheters inserted via sinus ostia (small openings connecting sinus to nasal pharynx)
Endoscopic removal of chondroids
Surgical flushing and removal of material
Describe gutteral pouch tympany
Foals Usually unilateral Marked retropharyngeal swelling Clinical signs of: swelling, resp stridor, dysphagia Confirmed on radiography or endoscopy
Describe temporohyoid osteoarthropathy
Progressive disease of the middle ear and bones of the temporohyoid joint (stylohyoid bone, squamous portion of temporal bone)
Aetiology: Middle or inner ear infection
What are the clinical signs of temporohyoid osteoarthropathy?
Early: head shaking, ear rubbing, behavioural chane
Chronic: facial nerve paralysis, head tilt, ataxia, nystagmus (toward affected side)
What are the ‘strap’ muscles?
Longus capitus
Rectus capitus ventralis
Rectus capitus lateralis
Why may the ‘strap’ neck muscles rupture?
Trauma
Usually due to rearing and falling over backwards
Which clinical signs are associated with rupture of the ‘strap’ muscles?
Profuse bilateral epistaxis Ataxia Head tilt Pharyngeal and tracheal compression and secondary upper airway obstruction
How do you diagnose rupture of the neck ‘strap’ muscles?
Endoscopy: roof of pharynx collapsed, normal vessels, swollen muscle bellies
Radiography: fluid lines within gutteral pouch
What is the treatment for rupture of the neck ‘strap’ muscles?
Stall rest
Dependent on degree of concurrent brain trauma or skull fracture
Anti-inflammatories
Supportive care
When is a tracheotomy carried out?
Emergency bypass of URT obstruction
Route for intubation
Rest the URT
Bypass inoperable URT obstruction
How would you perform an emergency tracheotomy?
Clip a 20 x 10cm area on ventral midline at junction between middle and upper third of neck
Palpate paired sternothyrohyoideus muscles and tracheal rings
Give 10ml LA (eg mepivacaine) into skin and underlying tissues
Aseptically prepare site
Make a 6-8cm incision on ventral midline of neck
Palpate the two tracheal rings in the centre of the incision
Make a stab incision between the two rings
Extend the incision for 1-2cm each side of the midline
Insert tracheotomy tube
Secure in place
Give some differential diagnoses for dysphagia
Oesophageal obstruction Retropharyngeal abscess (eg strangles) Retropharyngeal mass (neoplasias, granuloma) Pharyngeal foreign body Gutteral pouch mycosis Equine grass sickness URT infection
Onchocerca cervicalis are found where?
Nuchal ligament
nematode
How big are pinworms?
2-13mm
What is the proper name for pinworm?
Oxyuris equi
What is urticaria?
Raised itchy rash
Wheals, oedema and pruritus
Sweet itch is caused by what?
Where on the horse is it seen?
Culicoides spp
Dorsal surface of horse: tail, mane, back
What does atopy mean?
Hyperallergic
How do you diagnose atopy?
Intradermal skin testing
What is the difference between scaling and crusting?
Scaling= dry, grey Crusting= yellow, red, brown, wet/damp
What is the difference between erosion and ulceration?
Erosion is superficial (partial loss of epithelial or mucosal surface that heals by resolution)
Ulceration is deeper (full thickness loss of epithelial or mucosal surface which heals by repair ie replacement with fibrous tissue)
Describe pemphigus foliaceus
Rare, autoimmune, horse makes antibodies against its own skin Severe crusting No age or sex predilection Dx: skin biopsy Tx: immunosuppressive drugs Prognosis: guarded
Viral papillomas are seen where?
Muzzle, face, pinna, inguinal area
Describe dermatophilosis congolensis
Gram +, facultative anaerobe, branching filaments on histology
Favourable conditions= skin trauma, wet skin
Thick, parakeratotic crusts (continuous epidermal invasion)
Tx: topical (mild cases), systemic antimicrobials (severe cases)
Bacterial folliculitis is caused by what?
Staphylococcus and streptococcus
Give an antifungal used to treat ringworm?
Miconazole
Describe leukocytoclastic vasculitis
Common, affects non-pigmented areas on distal limb
Results from deposition of immune complexes at vessel wall
Painful
Dx: skin biopsy
Tx: corticosteroids, avoid exposure to light
Describe pastern dermatitis
‘Greasy heel’ syndrome
Very common
Caused by chronic wetting of skin on distal heel
Winter, white limbs
What are warbles?
Larval stages of Hypoderma bovis and lineatum, appear as nodule with a central pore (larvae inside)
Neck and trunk
Often painful
Tx: enlargement of pore to remove central grub
What is an atheroma?
Degeneration of the walls of the arteries caused by accumulated fatty deposits and scar tissue
Leads to restriction of circulation -> thrombosis
What types of skin tumours are present in horses?
Sarcoids
Melanoma
Squamous cell carcinoma
Mast cell tumour
Describe sarcoids
Most common skin tumour in horses
Tumour of fibroblasts
Bovine papillomavirus 1 and 2 are most likely cause
6 clinical presentations: occult, verrucous, nodular, fibroblastic, mixed, malignant
Dx: biopsy
Tx: surgery, immune therapy, cytotoxics,
Where are melanomas usually seen?
Perineum, tail head (near anus), parotid region
How do you treat a melanoma?
Surgical excision, immunotherapy
Where are squamous cell carcinomas usually seen?
Poorly pigmented animals
External genitalia, eyes
Where are mast cell rumours found?
Head
Solitary
Males
How is equine herpes virus spread?
Mainly be respiratory route
Aborted foetus/ membranes/ vaginal discharge are highly contagious
How do large and small strongyles affect the colon?
Large: verminous arteritis, thromboembolic colic
Small: submucosal inflammation
Give some haematological changes associated with parasitism?
Neutrophilia, hypoalbuminaemia, hyperglobulinaemia
NOT eosinophilia
What are the two divisions of equine gastric ulcer syndrome?
Give possible risk factors for each
EGGUS: Equine glandular gastric ulcer syndrome (bother horses mοre, harder to treat). Risk factors= possibly stress, NSAID-related.
ESGUS: Equine squamous gastric ulcer syndrome. Risk factor= acid injury.
What are the signs of EGUS (equine gastric ulcer syndrome)?
Weight loss, poor performance
Selective appetite, slow eating, prefer roughage over grain
Bad/cranky behaviou
Colic very unlikely
What is the pH in the two parts of the stomach?
Squamous portion prone to acid injury: pH 5.4
Glandular, acid-secreting portion protected from acid injury by mucous layer: 1.8
Where do ESGUS and EGGUS usually occur?
ESGUS: Caused by ‘splashing’ of stomach acid onto the unprotected mucosal lining above the margo plicatus, on squamous portion of stomach
EGGUS: below margo plicatus on glandular portion of stomach, when protective lining breaks down, exposing the mucosa to acids
Why is the horse so susceptible to gastric ulcers?
Stomach anatomy -> poor mixing of food, grain portion is rapidly fermentable -> acid production
Give some predisposing factors to acid injury leading to gastric ulcers
High concentrate diets -> volatile fatty acids and indirect acid injury via gastrin production in response to absorbed CHO (carbohydrates)
Also, low fibre concentrations -> reduced saliva production (saliva is an acid buffer)
Exercise -> gastrin production, also increased abdominal pressure can promote ‘splashing’ of acid onto unprotected squamous portion
How do you diagnose gastric ulcers?
Gastroscopy - 3m endoscope
Why is a faecal occult blood test not reliable for diagnosing gastric ulcers?
False negatives
How do you treat gastric ulcers?
Omeprazole (proton pump inhibitor)
- Buffered
- Enteric coated
- Plain
EGGUS requires higher doses
Give some clinical signs of colic in order of increasing severity
Flank watching Lying down Pawing the ground Rolling Repeatedly getting up and down Violent thrashing around
Give the different classifications of colic
Spasmodic Impactions Gas distension Obstructions (simple/ strangulating) Non-strangulating infarction Inflammation (enteritis/ colitis) Idiopathic
How do severe cases of colic lead to shock?
Loss of vascular supply to mucosa
Absorption of endotoxins into the circulation
Systemic inflammatory response system (SIRS)
What percentage of colic cases require surgery?
7%
What initial advice should you give to an owner of a horse with suspected colic?
Put horse in a well bedded stable
Remove anything it could injure itself on (buckets, feed etc)
Let horse roll if it wants to
A short period (10 mins) of walking exercise is fine but nothing longer before seeing a vet
Which sedative should you give to a horse with colic when examining it?
Xylazine iv (200mg for a 500kg horse) Also gives analgesia
Which questions should you ask a horse owner when investigating colic?
Which signs were observed?
When did these start/ when was the horse last normal?
Feed intake and faecal output over last 24 hours
Any diarrhoea?
History of equine grass sickness on premises?
Which structures are identifiable during a rectal palpation?
Pelvic flexure Caecum Spleen Nephrosplenic space Small (descending) colon Inguinal rings
What are some common findings when doing a rectal exam to investigate colic?
Distended SI Pelvic flexure impaction Left dorsal displacement Right dorsal displacement Large colon torsion Caecal impaction Small colon impaction
What sized needle should you use when doing an abdominocentesis?
18g, 1.5 inch
What is the appearance of normal peritoneal fluid?
Clear, straw-coloured
Regarding peritoneal fluid, what are the normal values for:
Total protein
WBCC
Lactate
Total protein:
What is the normal packed cell volume of a horse?
35-45%
What is the normal value for systemic total protein?
60-70g/L
Which diagnostic tests should you do when investigating colic?
Haematology (systemic lactate, WBC, systemic TP) Rectal exam Abdominocentesis Nasogastric intubation Ultrasound
What is the most common cause of colic in the foal?
Meconium impaction
What is the medical term for equine grass sickness?
Equine dysautonomia
What is the suspected cause of equine grass sickness?
Clostridium botulinum type C (exists in soil)
Acute, subacute, and chronic forms
Affects autonomic nervous system -> reduced GI motility
Causes a paralytic ileus (obstruction of ileum)
Patchy sweating, tachycardia
Fatal
What are the functions of the upper airways?
Channel for conveying airflow to and from lung
Filtering and conditioning of inspired air
Protection of lower airway from aspiration
Olfaction
Phonation
Swallowing
Thermoregulation
Why is a normal upper airway so critical in a horse in particular?
Because the horse is an obligate nasal breather
What is the tidal volume of a horse at rest?
5L
What is meant by tidal volume?
Lung volume, representing the normal volume of air displaced between normal inhalation and exhalation
What is the minute ventilation of a horse at rest and during exercise?
Rest: 75L
Exercise: 1500L (20x increase)
How do you work out minute ventilation?
Tidal volume x resp rate
Give some clinical signs of upper airway disease
Nasal discharge
Respiratory distress
Exercise intolerance
Noise at exercise
When investigating URT disease, what should you look out for regarding nasal discharge?
Is it unilateral/bilateral? Chronicity Nature of discharge (blood/purulent/serous/food material) Recent head trauma? Recent URT infection? Is it associated with exercise? Any cough/ resp noise? Any facial swelling? Any response to treatment?
When investigating URT disease, what should you look out for regarding respiratory noise?
When does it occur (rest/ exercise?)
If it occurs at exercise, what pace does it occur at?
Is the noise inspiratory/ expiratory/ both?
What does it sound like? (Whistle, roar, gurgle, snoring)
Continuous/ intermittent?
If at exercise, does the horse stop/ slow down when it occurs?
Does the noise disappear once the horse’s speed reduces?
Does the noise limit the horse’s performance?
Does the horse recover normally after exercise?
When doing a clinical exam of the head, what should you look for?
Symmetry Nasal/ocular discharge Airflow from both nostrils Percussion of sinuses Palpation of larynx Evidence of previous surgical scars
In RLN (recurrent laryngeal neuropathy- roaring), which Cricoarytenoideus dorsalis muscle is atrophied?
Left
How can you determine whether a noise made at exercise is made during inspiration or expiration?
Expiration occurs as the leading leg hits the ground at canter and gallop
Is ‘roaring’ heard during inspiration or expiration?
Inspiration
Does dorsal displacement of the soft palate causes respiratory noises during inspiration or expiration?
Both:
Expiration= loud
Inspiration= soft gurgling
Give some causes of abnormal respiratory noises heard at exercise
RLN (recurrent laryngeal neuropathy) DDSP Epiglottic entrapment Subepiglottic cyst Epiglottic retroversion 4-BAD (fourth branchial arch defect) Alar fold collapse/ nasal paralysis ADAF (axial deviation of the aryepiglottic folds)
Which structures you examine with an endoscopy when investigating abnormal respiratory noises?
Nasal passages Sinus drainage angles Ethmoturbinates Nasopharynx Larynx Gutteral pouches
What is the only way of identifying causes of URT obstruction that only occur at exercise?
Exercise endoscopy (High speed treadmill endoscopy= gold standard Can also use dynamic respiratory endoscope-attaches to bridle)
How can you tell if a nasal obstruction is present above or below the nasal septum?
Rostral to nasal septum=unilateral discharge
Above nasal septum=bilateral discharge
When doing radiography, the latero-lateral view is good for assessing which structures?
Paranasal sinuses, gutteral pouches and pharynx
When doing radiography, lateral oblique views are good for assessing which structures?
Peri-apical regions of the premolars and molars (prevents superimposition)
When doing radiography, the dorso-ventral view is good for assessing which structures?
Paranasal sinuses, nasal septum and teeth
Helps to decode of lesions are unilateral or bilateral
Why might you perform a sinoscopy?
Investigate suspected paranasal sinus disease
Obtain material for biopsy
Treatment
Which diagnostic techniques might you use to investigate suspected masses?
MRI
CT scan
What is scintigraphy?
Radio isotopes are administered IV
The emitted radiation is measured by external detectors to produce 2D images
When might you use scintigraphy?
Investigation of orthopaedic disease (eg fracture identification)
Suspected TMJ disease
Identification of damaged tooth
Differentiation between primary and secondary sinusitis
How can you investigate alar folds collapse?
Temporary suture across bridge of nose, if resolves, alar folds collapse is cause of problem
Which bone separates the left and right nasal passages?
Nasal septum and vomer bone
The nasal passages are divided into which 3 sections?
Dorsal, middle, ventral meatus
What are the clinical signs of a problem with the nasal passages?
Nasal discharge Halitosis Abnormal respiratory noise Coughing Facial distortion Head shaking
How can you diagnose problems with the nasal passages?
Radiography
Ultrasound
CT scan
What is wry nose?
Congenital shortening of maxilla, nasal and vomer bones
Causes laterally deviated rostral maxilla and associated nasal septum deviation
Nasal obstruction
Usually accompanied by malocclusion of the teeth
Give some causes of disease in the nasal passages
Trauma Wry nose Deviation or thickening of the nasal septum Neoplasia (carcinoma) Progressive ethmoidal haematoma Fungal infection
When placing an nasogastric tube, which meatus should it pass through?
Ventral (less likely to damage ethmoturbinates)
Use lubricant on end of tube, don’t force it when you hit resistance
What is an ethmoid haematoma?
Encapsulated non-neoplastic mass
Grows into the nasal passages/paranasal sinuses
Unknown aetiology
What are the clinical signs of an ethmoid haematoma?
Mild intermittent unilateral epistaxis
Occasionally abnormal resp noise at exercise
+/- bad smell
How can you diagnose an ethmoid haematoma?
Endoscopy +/- radiography
CT scan
How do you treat an ethmoid haematoma?
Lesions in the nasal passages can be treated with intra-lesional formalin (causes aggressive necrosis of haematoma), however there is potential damage to sinus lining
Laser removal
Surgical removal
Recurrence common
What are the clinical signs of fungal rhinitis (nasal aspergillosis)?
How do you diagnose and treat it?
Unilateral purulent/ occasionally haemorrhagic nasal discharge
Foul smell
Occasionally nasal stertor
Diagnosis: endoscopy
Treatment: removal of fungal plaques and necrotic bone Topical treatment (nystatin powder)
Name the seven pairs of paranasal sinuses
Rostral maxillary Caudal maxillary Frontal Dorsal conchal Ventral conchal Sphenopalatine Ethmoid
How does drainage of sinuses occur?
Gravity and mucociliary action
Where do the other sinuses (apart from rostral maxillary and ventral conchal sinuses) drain?
Into the caudal maxillary sinus -> Middle meatus via the nasomaxillary aperture
What are the clinical signs of paranasal sinus disease?
Unilateral/bilateral nasal discharge (serous/purulent/mucopurulent/ occasionally haemorrhagic)
+/- facial swelling
+/- decreased nasal airflow (depending on amount of secondary oedema)
Fluid lines within a sinus on a radiograph indicate what?
Sinusitis
What is the difference between primary and secondary sinusitis?
Primary: usually results from previous resp tract infection, most commonly infection by streptococcus spp
Secondary: to bother condition, primarily dental disease die to the proximity of the alveolar bone to the maxillary sinuses (08, 09, 10, 11)
How do you treat primary sinusitis?
Rule out strep equi var equi (strangles)
Place on antibiotics eg trimethoprim sulphonamides for 7-14 days
Feed from the ground to encourage drainage
Dust-free management
Turnout as much as possible
Which structure may obstruct the drainage angle of the ventral conchal sinus?
Maxillary septal bulla
How may you surgically approach the paranasal sinuses?
Trephination or bone flap
How do you treat sinusitis that is secondary to peri-apical tooth infection?
Remove affected tooth
Flush sinuses
How do you treat sinusitis that is secondary to a facial fracture?
Remove/stabilise bone fragments
Flush sinuses
Give some clinical signs associated with paranasal sinus cysts
Facial swelling
Reduced nasal airflow
Nasal discharge
Nasal stertor
How do you treat a paranasal sinus cyst?
Surgical removal
What is suturitis?
Periostitis of the suture lines between the nasal and frontal bones
Bilateral firm non-painful swellings in the nasofrontal region
Usually regress with time
What are the two main functions of the pharynx?
Deliver air from the nasal cavity to the larynx
Provides a pathway for food from the oral cavity to the oesophagus
What separates the nasopharynx from the oropharynx?
Soft palate
Why does the pharynx have the potential to collapse during exercise?
Lacks rigid support by bone/cartilage
How does the pharynx retain stability?
Coordinated neuromuscular function
Which nerves innervate the pharynx?
Mandibular branch of trigeminal
Pharyngeal branch of vagus
Hypoglossal
Cervical nerves
What are the main functions of the larynx?
Breathing (communication between pharynx and trachea)
Protect lower airway (prevent inhalation of food during swallowing)
Phonation/ vocalisation
Which cartilages make up the larynx?
Cricoid cartilage
Thyroid cartilage
Epiglottis
Paired arytenoid cartilages
Which muscle is the principle abductor of the glottis?
Cricoarytenoideus dorsalis
Which muscle is the principle adductor of the glottis?
Cricoarytenoidalis lateralis
When does the glottis open and close?
Open: exercise
Close: swallowing
Describe the slap test
Used to diagnose left recurrent laryngeal neuropathy (roaring)
Involves slapping one hemithorax to cause a reflex adduction of the muscular process of the arytenoid cartilage on the opposite side
Which diagnostic techniques can be used to examine the larynx and pharynx?
Endoscopy- exercise and at rest
Radiography
Ultrasound
Give some clinical signs associated with problems with the pharynx
Poor performance Respiratory noise Dysphagia (difficulty swallowing) Nasal discharge Coughing Respiratory distress
Give some diseases associated with the pharynx
Cleft palate Pharyngeal lymphoid hyperplasia DDSP (dorsal displacement of soft palate, can be persistent or intermittent) Palatal instability Pharyngeal collapse Pharyngeal mass Foreign body
When does intermittent dorsal displacement of the soft palate tend to occur?
What happens?
Intense exercise
Soft palate displaces dorsally resulting in an expiratory obstruction
Is intermittent or persistent dorsal displacement of the soft palate often secondary to other disease?
Persistent
Eg epiglottic entrapment, sub-epiglottic ulcer, sub-epiglottic cyst
Give some clinical signs of dorsal displacement of the soft palate
Exercise intolerance
Gurgling/vibrating noise
Rider reports ‘choking/swallowing its tongue’
How can you diagnose DDSP (dorsal displacement of soft palate)?
Endoscopy: resting (limited value) and during exercise (gold standard)
What is the function of thyrohyoideus?
Draws pharynx and larynx rostrally
What is a ‘tie-back’ procedure?
Operation to resolve roaring
Arytenoid cartilage is pulled to the side and sutured to keep it from interfering with airflow
What causes intermittent dorsal displacement of soft palate (IDDSP)?
Neuromuscular dysfunction:
- Pharyngeal branch of vagus nerve/Hypoglossal
- Thyrohyoideus
- Alteration in laryngohyoid position
- Inflammation
Which conservative treatment could you use to treat intermittent dorsal displacement of soft palate (IDDSP)?
Get horses fit
Change tack
Treat inflammatory conditions of the pharynx and gutteral pouch
Try throat support device?
How can you surgically treat dorsal displacement of the soft palate?
Staphylectomy: partial soft palate resection
Myectomy: removal of some of the extrinsic muscles of the larynx, reduced caudal retraction of the larynx
Induction of palatal fibrosis: thermal/laser cautery, stiffens soft palate
Tie forward: BEST, sutures placed between basihyoid bone and thyroid cartilage, positions larynx more rostrally and dorsally
How would you identify a foal with cleft palate?
Milk at nostril
What clinical signs are seen with laryngeal problems?
Respiratory noise Poor performance Dysphagia Coughing Respiratory distress
Explain recurrent laryngeal neuropathy
Common, large breeds
Unilateral paralysis of the left arytenoid cartilage
Progressive loss of myelinated nerve fibres in the left recurrent laryngeal nerve
Atrophy of cricoarytenoidalis dorsalis muscle
Loss of abductor and adductor function
How do you diagnose RLN (recurrent laryngeal neuropathy)?
Abnormal inspiratory noise at exercise - roaring
Poor performance
Clinical exam: +/- atrophy of CAD, negative result on slap test
Endoscopy at rest: asses synchrony of movement, ability to achieve and maintain full abduction (grade 1-4: Havemeyer scale)
Dynamic endoscopy is gold standard to asses degree of collapse during exercise
Describe the 4 grades of the Havemeyer scale when grading RLN (recurrent laryngeal neuropathy)
I: all arytenoid cartilage movements are synchronous and symmetrical. Full arytenoid abduction can be achieved and maintained.
II: arytenoid cartilage movements are asynchronous but full abduction can be achieved and maintained (sub-grades: 1.Transient 2.Permanent)
III. arytenoid cartilage movements are asynchronous and/or asymmetric. Full arytenoid abduction cannot be achieved and maintained (1.Occasions of symmetrical abduction 2.Obvious asymmetry 3.Marked but not total asymmetry)
IV. Complete immobility of the arytenoid cartilage and vocal fold
How can you treat RLN (recurrent laryngeal neuropathy)?
Ventriculectomy
Laryngoplasty (‘tie back’)
Describe a ventriculectomy procedure
Used to treat RLN (recurrent laryngeal neuropathy)
‘Hob day’ procedure
Roaring burr used to every left or both ventricles, which are then excised
+/- vocal cord removed at same time
Describe a ‘tie-back’ procedure
Used to treat RLN (recurrent laryngeal neuropathy)
Suture placed between dorsocaudal edge of cricoid cartilage and muscular process of arytenoid cartilage
Mimics the action of CAD (Cricoarytenoideus dorsalis)
Results in permanent abduction of left arytenoid cartilage
Give some complications of tie-back procedures
Failure Dysphagia Aspiration Persistent cough Infection
Give some causes of laryngeal paralysis (besides RLN)
Gutteral pouch disease
Peripheral neuropathy (eg liver disease)
Organophosphate poisoning
Fourth branchial arch arch defect (4BAD) affects which side of the larynx?
Right side
Explain fourth branchial arch defect
Variable development of the right laryngeal cartilage
Right-sided asymmetry
Rostral displacement of palatopharyngeal arch
Variable ability to abduct right arytenoid cartilage
What is vocal cord collapse (VCC) associated with?
ADAF
Axial deviation of aryepiglottic folds
Describe arytenoid chondritis
Mucosal ulceration
Infection of arytenoid cartilage
Progressive
Respiratory obstruction (younger TB, older mares)
What are the gutteral pouches?
Air-filled mucosa-lined outpouchings of the auditory tubes connecting the nasopharynx to the middle ear
Present in horses but no other domestic species
Paired
350ml in volume
Which structures border the gutteral pouches?
Dorsal: base of skull, first cervical vertebra, tympanic bulla, auditory meatus
Medial: median septum, rectus and longus capitis muscles
Ventral: nasopharynx, retropharyngeal lymph nodes
Lateral: parotid and mandibular salivary glands, Pterygoid muscles
How are gutteral pouches separated?
Separated into a medial and lateral compartment by the stylohyoid bone
Medial is bigger than lateral
Where do gutteral pouches empty?
Nasopharynx via a funnel-shaped orifice that has a fibrocartilage flap
Internal and external carotid arteries supply which compartment of gutteral pouches?
Internal: medial compartment
External: lateral compartment
What are the clinical signs of gutteral pouch disease?
Epistaxis Swelling/dyspnoea Nasal discharge Nerve dysfunction -dysphagia -laryngeal paralysis -Horner's syndrome (constructed pupil) -facial asymmetry
Give some diseases associated with gutteral pouches
Mycosis
Empyema/chondroids
Tympany
Otitis interna/media
Stylohyoid bone: temporohyoid osteopathy, fracture of petrous temporal/basisphenoid
Rupture of longus capitus ‘strap’ muscle
Neoplasia/cysts/foreign bodies
Describe gutteral pouch mycosis
Primary fungal plaque forms over vessels (most commonly internal carotid)
Uncommon but potentially life-threatening
What are the clinical signs of gutteral pouch mycosis?
Nasal discharge
Epistaxis
+/- nerve dysfunction: dysphagia, Horners (pupil constriction), laryngeal paralysis
How do you diagnose gutteral pouch mycosis?
Endoscopy
How do you treat gutteral pouch mycosis?
Surgical occlusion of affected artery: simple ligation (back flow from circle of Willis), or balloon catheterisation, or coil embolisation
Medical management if no history of bleeding: antifungals
Describe gutteral pouch empyema
Purulent material (chondroids) within one or both gutteral pouches
Usually in young horses
Aetiology: URT infection, irritant drugs
What are the clinical signs of gutteral pouch empyema?
Intermittent nasal discharge Parotid swelling and pain Extended head carriage Respiratory noise at rest Difficulty eating and swallowing Occasionally pharyngeal and laryngeal paresis
How do you diagnose gutteral pouch chondroids?
Radiography (increase radiodensity-whiteness- of gutteral pouches on lateral views
Endoscopy (dorsal pharyngeal compression, purulent material in gutteral pouches)
How do you treat chondroids?
Flushing of gutteral pouches using catheters inserted via sinus ostia (small openings connecting sinus to nasal pharynx)
Endoscopic removal of chondroids
Surgical flushing and removal of material
Describe gutteral pouch tympany
Foals Usually unilateral Marked retropharyngeal swelling Clinical signs of: swelling, resp stridor, dysphagia Confirmed on radiography or endoscopy
Describe temporohyoid osteoarthropathy
Progressive disease of the middle ear and bones of the temporohyoid joint (stylohyoid bone, squamous portion of temporal bone)
Aetiology: Middle or inner ear infection
What are the clinical signs of temporohyoid osteoarthropathy?
Early: head shaking, ear rubbing, behavioural chane
Chronic: facial nerve paralysis, head tilt, ataxia, nystagmus (toward affected side)
What are the ‘strap’ muscles?
Longus capitus
Rectus capitus ventralis
Rectus capitus lateralis
Why may the ‘strap’ neck muscles rupture?
Trauma
Usually due to rearing and falling over backwards
Which clinical signs are associated with rupture of the ‘strap’ muscles?
Profuse bilateral epistaxis Ataxia Head tilt Pharyngeal and tracheal compression and secondary upper airway obstruction
How do you diagnose rupture of the neck ‘strap’ muscles?
Endoscopy: roof of pharynx collapsed, normal vessels, swollen muscle bellies
Radiography: fluid lines within gutteral pouch
What is the treatment for rupture of the neck ‘strap’ muscles?
Stall rest
Dependent on degree of concurrent brain trauma or skull fracture
Anti-inflammatories
Supportive care
When is a tracheotomy carried out?
Emergency bypass of URT obstruction
Route for intubation
Rest the URT
Bypass inoperable URT obstruction
How would you perform an emergency tracheotomy?
Clip a 20 x 10cm area on ventral midline at junction between middle and upper third of neck
Palpate paired sternothyrohyoideus muscles and tracheal rings
Give 10ml LA (eg mepivacaine) into skin and underlying tissues
Aseptically prepare site
Make a 6-8cm incision on ventral midline of neck
Palpate the two tracheal rings in the centre of the incision
Make a stab incision between the two rings
Extend the incision for 1-2cm each side of the midline
Insert tracheotomy tube
Secure in place
Give some differential diagnoses for dysphagia
Oesophageal obstruction Retropharyngeal abscess (eg strangles) Retropharyngeal mass (neoplasias, granuloma) Pharyngeal foreign body Gutteral pouch mycosis Equine grass sickness URT infection
Onchocerca cervicalis are found where?
Nuchal ligament
nematode
How big are pinworms?
2-13mm
What is the proper name for pinworm?
Oxyuris equi
What is urticaria?
Raised itchy rash
Wheals, oedema and pruritus
Sweet itch is caused by what?
Where on the horse is it seen?
Culicoides spp
Dorsal surface of horse: tail, mane, back
What does atopy mean?
Hyperallergic
How do you diagnose atopy?
Intradermal skin testing
What is the difference between scaling and crusting?
Scaling= dry, grey Crusting= yellow, red, brown, wet/damp
What is the difference between erosion and ulceration?
Erosion is superficial (partial loss of epithelial or mucosal surface that heals by resolution)
Ulceration is deeper (full thickness loss of epithelial or mucosal surface which heals by repair ie replacement with fibrous tissue)
Describe pemphigus foliaceus
Rare, autoimmune, horse makes antibodies against its own skin Severe crusting No age or sex predilection Dx: skin biopsy Tx: immunosuppressive drugs Prognosis: guarded
Viral papillomas are seen where?
Muzzle, face, pinna, inguinal area
Describe dermatophilosis congolensis
Gram +, facultative anaerobe, branching filaments on histology
Favourable conditions= skin trauma, wet skin
Thick, parakeratotic crusts (continuous epidermal invasion)
Tx: topical (mild cases), systemic antimicrobials (severe cases)
Bacterial folliculitis is caused by what?
Staphylococcus and streptococcus
Give an antifungal used to treat ringworm?
Miconazole
Describe leukocytoclastic vasculitis
Common, affects non-pigmented areas on distal limb
Results from deposition of immune complexes at vessel wall
Painful
Dx: skin biopsy
Tx: corticosteroids, avoid exposure to light
Describe pastern dermatitis
‘Greasy heel’ syndrome
Very common
Caused by chronic wetting of skin on distal heel
Winter, white limbs
What are warbles?
Larval stages of Hypoderma bovis and lineatum, appear as nodule with a central pore (larvae inside)
Neck and trunk
Often painful
Tx: enlargement of pore to remove central grub
What is an atheroma?
Degeneration of the walls of the arteries caused by accumulated fatty deposits and scar tissue
Leads to restriction of circulation -> thrombosis
What types of skin tumours are present in horses?
Sarcoids
Melanoma
Squamous cell carcinoma
Mast cell tumour
Describe sarcoids
Most common skin tumour in horses
Tumour of fibroblasts
Bovine papillomavirus 1 and 2 are most likely cause
6 clinical presentations: occult, verrucous, nodular, fibroblastic, mixed, malignant
Dx: biopsy
Tx: surgery, immune therapy, cytotoxics,
Where are melanomas usually seen?
Perineum, tail head (near anus), parotid region
How do you treat a melanoma?
Surgical excision, immunotherapy
Where are squamous cell carcinomas usually seen?
Poorly pigmented animals
External genitalia, eyes
Where are mast cell rumours found?
Head
Solitary
Males
How is equine herpes virus spread?
Mainly be respiratory route
Aborted foetus/ membranes/ vaginal discharge are highly contagious
How do large and small strongyles affect the colon?
Large: verminous arteritis, thromboembolic colic
Small: submucosal inflammation
Give some haematological changes associated with parasitism?
Neutrophilia, hypoalbuminaemia, hyperglobulinaemia
NOT eosinophilia
What are the two divisions of equine gastric ulcer syndrome?
Give possible risk factors for each
EGGUS: Equine glandular gastric ulcer syndrome (bother horses mοre, harder to treat). Risk factors= possibly stress, NSAID-related.
ESGUS: Equine squamous gastric ulcer syndrome. Risk factor= acid injury.
What are the signs of EGUS (equine gastric ulcer syndrome)?
Weight loss, poor performance
Selective appetite, slow eating, prefer roughage over grain
Bad/cranky behaviou
Colic very unlikely
What is the pH in the two parts of the stomach?
Squamous portion prone to acid injury: pH 5.4
Glandular, acid-secreting portion protected from acid injury by mucous layer: 1.8
Where do ESGUS and EGGUS usually occur?
ESGUS: Caused by ‘splashing’ of stomach acid onto the unprotected mucosal lining above the margo plicatus, on squamous portion of stomach
EGGUS: below margo plicatus on glandular portion of stomach, when protective lining breaks down, exposing the mucosa to acids
Why is the horse so susceptible to gastric ulcers?
Stomach anatomy -> poor mixing of food, grain portion is rapidly fermentable -> acid production
Give some predisposing factors to acid injury leading to gastric ulcers
High concentrate diets -> volatile fatty acids and indirect acid injury via gastrin production in response to absorbed CHO (carbohydrates)
Also, low fibre concentrations -> reduced saliva production (saliva is an acid buffer)
Exercise -> gastrin production, also increased abdominal pressure can promote ‘splashing’ of acid onto unprotected squamous portion
How do you diagnose gastric ulcers?
Gastroscopy - 3m endoscope
Why is a faecal occult blood test not reliable for diagnosing gastric ulcers?
False negatives
How do you treat gastric ulcers?
Omeprazole (proton pump inhibitor)
- Buffered
- Enteric coated
- Plain
EGGUS requires higher doses
Give some clinical signs of colic in order of increasing severity
Flank watching Lying down Pawing the ground Rolling Repeatedly getting up and down Violent thrashing around
Give the different classifications of colic
Spasmodic Impactions Gas distension Obstructions (simple/ strangulating) Non-strangulating infarction Inflammation (enteritis/ colitis) Idiopathic
How do severe cases of colic lead to shock?
Loss of vascular supply to mucosa
Absorption of endotoxins into the circulation
Systemic inflammatory response system (SIRS)
What percentage of colic cases require surgery?
7%
What initial advice should you give to an owner of a horse with suspected colic?
Put horse in a well bedded stable
Remove anything it could injure itself on (buckets, feed etc)
Let horse roll if it wants to
A short period (10 mins) of walking exercise is fine but nothing longer before seeing a vet
Which sedative should you give to a horse with colic when examining it?
Xylazine iv (200mg for a 500kg horse) Also gives analgesia
Which questions should you ask a horse owner when investigating colic?
Which signs were observed?
When did these start/ when was the horse last normal?
Feed intake and faecal output over last 24 hours
Any diarrhoea?
History of equine grass sickness on premises?
Which structures are identifiable during a rectal palpation?
Pelvic flexure Caecum Spleen Nephrosplenic space Small (descending) colon Inguinal rings
What are some common findings when doing a rectal exam to investigate colic?
Distended SI Pelvic flexure impaction Left dorsal displacement Right dorsal displacement Large colon torsion Caecal impaction Small colon impaction
What sized needle should you use when doing an abdominocentesis?
18g, 1.5 inch
What is the appearance of normal peritoneal fluid?
Clear, straw-coloured
Regarding peritoneal fluid, what are the normal values for:
Total protein
WBCC
Lactate
Total protein:
What is the normal packed cell volume of a horse?
35-45%
What is the normal value for systemic total protein?
60-70g/L
Which diagnostic tests should you do when investigating colic?
Haematology (systemic lactate, WBC, systemic TP) Rectal exam Abdominocentesis Nasogastric intubation Ultrasound
What is the most common cause of colic in the foal?
Meconium impaction
What is the medical term for equine grass sickness?
Equine dysautonomia
What is the suspected cause of equine grass sickness?
Clostridium botulinum type C (exists in soil)
Acute, subacute, and chronic forms
Affects autonomic nervous system -> reduced GI motility
Causes a paralytic ileus (obstruction of ileum)
Patchy sweating, tachycardia
Fatal
What are the functions of the upper airways?
Channel for conveying airflow to and from lung
Filtering and conditioning of inspired air
Protection of lower airway from aspiration
Olfaction
Phonation
Swallowing
Thermoregulation
Why is a normal upper airway so critical in a horse in particular?
Because the horse is an obligate nasal breather
What is the tidal volume of a horse at rest?
5L
What is meant by tidal volume?
Lung volume, representing the normal volume of air displaced between normal inhalation and exhalation
What is the minute ventilation of a horse at rest and during exercise?
Rest: 75L
Exercise: 1500L (20x increase)
How do you work out minute ventilation?
Tidal volume x resp rate
Give some clinical signs of upper airway disease
Nasal discharge
Respiratory distress
Exercise intolerance
Noise at exercise
When investigating URT disease, what should you look out for regarding nasal discharge?
Is it unilateral/bilateral? Chronicity Nature of discharge (blood/purulent/serous/food material) Recent head trauma? Recent URT infection? Is it associated with exercise? Any cough/ resp noise? Any facial swelling? Any response to treatment?
When investigating URT disease, what should you look out for regarding respiratory noise?
When does it occur (rest/ exercise?)
If it occurs at exercise, what pace does it occur at?
Is the noise inspiratory/ expiratory/ both?
What does it sound like? (Whistle, roar, gurgle, snoring)
Continuous/ intermittent?
If at exercise, does the horse stop/ slow down when it occurs?
Does the noise disappear once the horse’s speed reduces?
Does the noise limit the horse’s performance?
Does the horse recover normally after exercise?
When doing a clinical exam of the head, what should you look for?
Symmetry Nasal/ocular discharge Airflow from both nostrils Percussion of sinuses Palpation of larynx Evidence of previous surgical scars
In RLN (recurrent laryngeal neuropathy- roaring), which Cricoarytenoideus dorsalis muscle is atrophied?
Left
How can you determine whether a noise made at exercise is made during inspiration or expiration?
Expiration occurs as the leading leg hits the ground at canter and gallop
Is ‘roaring’ heard during inspiration or expiration?
Inspiration
Does dorsal displacement of the soft palate causes respiratory noises during inspiration or expiration?
Both:
Expiration= loud
Inspiration= soft gurgling
Give some causes of abnormal respiratory noises heard at exercise
RLN (recurrent laryngeal neuropathy) DDSP Epiglottic entrapment Subepiglottic cyst Epiglottic retroversion 4-BAD (fourth branchial arch defect) Alar fold collapse/ nasal paralysis ADAF (axial deviation of the aryepiglottic folds)
Which structures you examine with an endoscopy when investigating abnormal respiratory noises?
Nasal passages Sinus drainage angles Ethmoturbinates Nasopharynx Larynx Gutteral pouches
What is the only way of identifying causes of URT obstruction that only occur at exercise?
Exercise endoscopy (High speed treadmill endoscopy= gold standard Can also use dynamic respiratory endoscope-attaches to bridle)
How can you tell if a nasal obstruction is present above or below the nasal septum?
Rostral to nasal septum=unilateral discharge
Above nasal septum=bilateral discharge
When doing radiography, the latero-lateral view is good for assessing which structures?
Paranasal sinuses, gutteral pouches and pharynx
When doing radiography, lateral oblique views are good for assessing which structures?
Peri-apical regions of the premolars and molars (prevents superimposition)
When doing radiography, the dorso-ventral view is good for assessing which structures?
Paranasal sinuses, nasal septum and teeth
Helps to decode of lesions are unilateral or bilateral
Why might you perform a sinoscopy?
Investigate suspected paranasal sinus disease
Obtain material for biopsy
Treatment
Which diagnostic techniques might you use to investigate suspected masses?
MRI
CT scan
What is scintigraphy?
Radio isotopes are administered IV
The emitted radiation is measured by external detectors to produce 2D images
When might you use scintigraphy?
Investigation of orthopaedic disease (eg fracture identification)
Suspected TMJ disease
Identification of damaged tooth
Differentiation between primary and secondary sinusitis
How can you investigate alar folds collapse?
Temporary suture across bridge of nose, if resolves, alar folds collapse is cause of problem
Which bone separates the left and right nasal passages?
Nasal septum and vomer bone
The nasal passages are divided into which 3 sections?
Dorsal, middle, ventral meatus
What are the clinical signs of a problem with the nasal passages?
Nasal discharge Halitosis Abnormal respiratory noise Coughing Facial distortion Head shaking
How can you diagnose problems with the nasal passages?
Radiography
Ultrasound
CT scan
What is wry nose?
Congenital shortening of maxilla, nasal and vomer bones
Causes laterally deviated rostral maxilla and associated nasal septum deviation
Nasal obstruction
Usually accompanied by malocclusion of the teeth
Give some causes of disease in the nasal passages
Trauma Wry nose Deviation or thickening of the nasal septum Neoplasia (carcinoma) Progressive ethmoidal haematoma Fungal infection
When placing an nasogastric tube, which meatus should it pass through?
Ventral (less likely to damage ethmoturbinates)
Use lubricant on end of tube, don’t force it when you hit resistance
What is an ethmoid haematoma?
Encapsulated non-neoplastic mass
Grows into the nasal passages/paranasal sinuses
Unknown aetiology
What are the clinical signs of an ethmoid haematoma?
Mild intermittent unilateral epistaxis
Occasionally abnormal resp noise at exercise
+/- bad smell
How can you diagnose an ethmoid haematoma?
Endoscopy +/- radiography
CT scan
How do you treat an ethmoid haematoma?
Lesions in the nasal passages can be treated with intra-lesional formalin (causes aggressive necrosis of haematoma), however there is potential damage to sinus lining
Laser removal
Surgical removal
Recurrence common
What are the clinical signs of fungal rhinitis (nasal aspergillosis)?
How do you diagnose and treat it?
Unilateral purulent/ occasionally haemorrhagic nasal discharge
Foul smell
Occasionally nasal stertor
Diagnosis: endoscopy
Treatment: removal of fungal plaques and necrotic bone Topical treatment (nystatin powder)
Name the seven pairs of paranasal sinuses
Rostral maxillary Caudal maxillary Frontal Dorsal conchal Ventral conchal Sphenopalatine Ethmoid
How does drainage of sinuses occur?
Gravity and mucociliary action
Where do the other sinuses (apart from rostral maxillary and ventral conchal sinuses) drain?
Into the caudal maxillary sinus -> Middle meatus via the nasomaxillary aperture
What are the clinical signs of paranasal sinus disease?
Unilateral/bilateral nasal discharge (serous/purulent/mucopurulent/ occasionally haemorrhagic)
+/- facial swelling
+/- decreased nasal airflow (depending on amount of secondary oedema)
Fluid lines within a sinus on a radiograph indicate what?
Sinusitis
What is the difference between primary and secondary sinusitis?
Primary: usually results from previous resp tract infection, most commonly infection by streptococcus spp
Secondary: to bother condition, primarily dental disease die to the proximity of the alveolar bone to the maxillary sinuses (08, 09, 10, 11)
How do you treat primary sinusitis?
Rule out strep equi var equi (strangles)
Place on antibiotics eg trimethoprim sulphonamides for 7-14 days
Feed from the ground to encourage drainage
Dust-free management
Turnout as much as possible
Which structure may obstruct the drainage angle of the ventral conchal sinus?
Maxillary septal bulla
How may you surgically approach the paranasal sinuses?
Trephination or bone flap
How do you treat sinusitis that is secondary to peri-apical tooth infection?
Remove affected tooth
Flush sinuses
How do you treat sinusitis that is secondary to a facial fracture?
Remove/stabilise bone fragments
Flush sinuses
Give some clinical signs associated with paranasal sinus cysts
Facial swelling
Reduced nasal airflow
Nasal discharge
Nasal stertor
How do you treat a paranasal sinus cyst?
Surgical removal
What is suturitis?
Periostitis of the suture lines between the nasal and frontal bones
Bilateral firm non-painful swellings in the nasofrontal region
Usually regress with time
What are the two main functions of the pharynx?
Deliver air from the nasal cavity to the larynx
Provides a pathway for food from the oral cavity to the oesophagus
What separates the nasopharynx from the oropharynx?
Soft palate
Why does the pharynx have the potential to collapse during exercise?
Lacks rigid support by bone/cartilage
How does the pharynx retain stability?
Coordinated neuromuscular function
Which nerves innervate the pharynx?
Mandibular branch of trigeminal
Pharyngeal branch of vagus
Hypoglossal
Cervical nerves
What are the main functions of the larynx?
Breathing (communication between pharynx and trachea)
Protect lower airway (prevent inhalation of food during swallowing)
Phonation/ vocalisation
Which cartilages make up the larynx?
Cricoid cartilage
Thyroid cartilage
Epiglottis
Paired arytenoid cartilages
Which muscle is the principle abductor of the glottis?
Cricoarytenoideus dorsalis
Which muscle is the principle adductor of the glottis?
Cricoarytenoidalis lateralis
When does the glottis open and close?
Open: exercise
Close: swallowing
Describe the slap test
Used to diagnose left recurrent laryngeal neuropathy (roaring)
Involves slapping one hemithorax to cause a reflex adduction of the muscular process of the arytenoid cartilage on the opposite side
Which diagnostic techniques can be used to examine the larynx and pharynx?
Endoscopy- exercise and at rest
Radiography
Ultrasound
Give some clinical signs associated with problems with the pharynx
Poor performance Respiratory noise Dysphagia (difficulty swallowing) Nasal discharge Coughing Respiratory distress
Give some diseases associated with the pharynx
Cleft palate Pharyngeal lymphoid hyperplasia DDSP (dorsal displacement of soft palate, can be persistent or intermittent) Palatal instability Pharyngeal collapse Pharyngeal mass Foreign body
When does intermittent dorsal displacement of the soft palate tend to occur?
What happens?
Intense exercise
Soft palate displaces dorsally resulting in an expiratory obstruction
Is intermittent or persistent dorsal displacement of the soft palate often secondary to other disease?
Persistent
Eg epiglottic entrapment, sub-epiglottic ulcer, sub-epiglottic cyst
Give some clinical signs of dorsal displacement of the soft palate
Exercise intolerance
Gurgling/vibrating noise
Rider reports ‘choking/swallowing its tongue’
How can you diagnose DDSP (dorsal displacement of soft palate)?
Endoscopy: resting (limited value) and during exercise (gold standard)
What is the function of thyrohyoideus?
Draws pharynx and larynx rostrally
What is a ‘tie-back’ procedure?
Operation to resolve roaring
Arytenoid cartilage is pulled to the side and sutured to keep it from interfering with airflow
What causes intermittent dorsal displacement of soft palate (IDDSP)?
Neuromuscular dysfunction:
- Pharyngeal branch of vagus nerve/Hypoglossal
- Thyrohyoideus
- Alteration in laryngohyoid position
- Inflammation
Which conservative treatment could you use to treat intermittent dorsal displacement of soft palate (IDDSP)?
Get horses fit
Change tack
Treat inflammatory conditions of the pharynx and gutteral pouch
Try throat support device?
How can you surgically treat dorsal displacement of the soft palate?
Staphylectomy: partial soft palate resection
Myectomy: removal of some of the extrinsic muscles of the larynx, reduced caudal retraction of the larynx
Induction of palatal fibrosis: thermal/laser cautery, stiffens soft palate
Tie forward: BEST, sutures placed between basihyoid bone and thyroid cartilage, positions larynx more rostrally and dorsally
How would you identify a foal with cleft palate?
Milk at nostril
What clinical signs are seen with laryngeal problems?
Respiratory noise Poor performance Dysphagia Coughing Respiratory distress
Explain recurrent laryngeal neuropathy
Common, large breeds
Unilateral paralysis of the left arytenoid cartilage
Progressive loss of myelinated nerve fibres in the left recurrent laryngeal nerve
Atrophy of cricoarytenoidalis dorsalis muscle
Loss of abductor and adductor function
How do you diagnose RLN (recurrent laryngeal neuropathy)?
Abnormal inspiratory noise at exercise - roaring
Poor performance
Clinical exam: +/- atrophy of CAD, negative result on slap test
Endoscopy at rest: asses synchrony of movement, ability to achieve and maintain full abduction (grade 1-4: Havemeyer scale)
Dynamic endoscopy is gold standard to asses degree of collapse during exercise
Describe the 4 grades of the Havemeyer scale when grading RLN (recurrent laryngeal neuropathy)
I: all arytenoid cartilage movements are synchronous and symmetrical. Full arytenoid abduction can be achieved and maintained.
II: arytenoid cartilage movements are asynchronous but full abduction can be achieved and maintained (sub-grades: 1.Transient 2.Permanent)
III. arytenoid cartilage movements are asynchronous and/or asymmetric. Full arytenoid abduction cannot be achieved and maintained (1.Occasions of symmetrical abduction 2.Obvious asymmetry 3.Marked but not total asymmetry)
IV. Complete immobility of the arytenoid cartilage and vocal fold
How can you treat RLN (recurrent laryngeal neuropathy)?
Ventriculectomy
Laryngoplasty (‘tie back’)
Describe a ventriculectomy procedure
Used to treat RLN (recurrent laryngeal neuropathy)
‘Hob day’ procedure
Roaring burr used to every left or both ventricles, which are then excised
+/- vocal cord removed at same time
Describe a ‘tie-back’ procedure
Used to treat RLN (recurrent laryngeal neuropathy)
Suture placed between dorsocaudal edge of cricoid cartilage and muscular process of arytenoid cartilage
Mimics the action of CAD (Cricoarytenoideus dorsalis)
Results in permanent abduction of left arytenoid cartilage
Give some complications of tie-back procedures
Failure Dysphagia Aspiration Persistent cough Infection
Give some causes of laryngeal paralysis (besides RLN)
Gutteral pouch disease
Peripheral neuropathy (eg liver disease)
Organophosphate poisoning
Fourth branchial arch arch defect (4BAD) affects which side of the larynx?
Right side
Explain fourth branchial arch defect
Variable development of the right laryngeal cartilage
Right-sided asymmetry
Rostral displacement of palatopharyngeal arch
Variable ability to abduct right arytenoid cartilage
What is vocal cord collapse (VCC) associated with?
ADAF
Axial deviation of aryepiglottic folds
Describe arytenoid chondritis
Mucosal ulceration
Infection of arytenoid cartilage
Progressive
Respiratory obstruction (younger TB, older mares)
What are the gutteral pouches?
Air-filled mucosa-lined outpouchings of the auditory tubes connecting the nasopharynx to the middle ear
Present in horses but no other domestic species
Paired
350ml in volume
Which structures border the gutteral pouches?
Dorsal: base of skull, first cervical vertebra, tympanic bulla, auditory meatus
Medial: median septum, rectus and longus capitis muscles
Ventral: nasopharynx, retropharyngeal lymph nodes
Lateral: parotid and mandibular salivary glands, Pterygoid muscles
How are gutteral pouches separated?
Separated into a medial and lateral compartment by the stylohyoid bone
Medial is bigger than lateral
Where do gutteral pouches empty?
Nasopharynx via a funnel-shaped orifice that has a fibrocartilage flap
Internal and external carotid arteries supply which compartment of gutteral pouches?
Internal: medial compartment
External: lateral compartment
What are the clinical signs of gutteral pouch disease?
Epistaxis Swelling/dyspnoea Nasal discharge Nerve dysfunction -dysphagia -laryngeal paralysis -Horner's syndrome (constructed pupil) -facial asymmetry
Give some diseases associated with gutteral pouches
Mycosis
Empyema/chondroids
Tympany
Otitis interna/media
Stylohyoid bone: temporohyoid osteopathy, fracture of petrous temporal/basisphenoid
Rupture of longus capitus ‘strap’ muscle
Neoplasia/cysts/foreign bodies
Describe gutteral pouch mycosis
Primary fungal plaque forms over vessels (most commonly internal carotid)
Uncommon but potentially life-threatening
What are the clinical signs of gutteral pouch mycosis?
Nasal discharge
Epistaxis
+/- nerve dysfunction: dysphagia, Horners (pupil constriction), laryngeal paralysis
How do you diagnose gutteral pouch mycosis?
Endoscopy
How do you treat gutteral pouch mycosis?
Surgical occlusion of affected artery: simple ligation (back flow from circle of Willis), or balloon catheterisation, or coil embolisation
Medical management if no history of bleeding: antifungals
Describe gutteral pouch empyema
Purulent material (chondroids) within one or both gutteral pouches
Usually in young horses
Aetiology: URT infection, irritant drugs
What are the clinical signs of gutteral pouch empyema?
Intermittent nasal discharge Parotid swelling and pain Extended head carriage Respiratory noise at rest Difficulty eating and swallowing Occasionally pharyngeal and laryngeal paresis
How do you diagnose gutteral pouch chondroids?
Radiography (increase radiodensity-whiteness- of gutteral pouches on lateral views
Endoscopy (dorsal pharyngeal compression, purulent material in gutteral pouches)
How do you treat chondroids?
Flushing of gutteral pouches using catheters inserted via sinus ostia (small openings connecting sinus to nasal pharynx)
Endoscopic removal of chondroids
Surgical flushing and removal of material
Describe gutteral pouch tympany
Foals Usually unilateral Marked retropharyngeal swelling Clinical signs of: swelling, resp stridor, dysphagia Confirmed on radiography or endoscopy
Describe temporohyoid osteoarthropathy
Progressive disease of the middle ear and bones of the temporohyoid joint (stylohyoid bone, squamous portion of temporal bone)
Aetiology: Middle or inner ear infection
What are the clinical signs of temporohyoid osteoarthropathy?
Early: head shaking, ear rubbing, behavioural chane
Chronic: facial nerve paralysis, head tilt, ataxia, nystagmus (toward affected side)
What are the ‘strap’ muscles?
Longus capitus
Rectus capitus ventralis
Rectus capitus lateralis
Why may the ‘strap’ neck muscles rupture?
Trauma
Usually due to rearing and falling over backwards
Which clinical signs are associated with rupture of the ‘strap’ muscles?
Profuse bilateral epistaxis Ataxia Head tilt Pharyngeal and tracheal compression and secondary upper airway obstruction
How do you diagnose rupture of the neck ‘strap’ muscles?
Endoscopy: roof of pharynx collapsed, normal vessels, swollen muscle bellies
Radiography: fluid lines within gutteral pouch
What is the treatment for rupture of the neck ‘strap’ muscles?
Stall rest
Dependent on degree of concurrent brain trauma or skull fracture
Anti-inflammatories
Supportive care
When is a tracheotomy carried out?
Emergency bypass of URT obstruction
Route for intubation
Rest the URT
Bypass inoperable URT obstruction
How would you perform an emergency tracheotomy?
Clip a 20 x 10cm area on ventral midline at junction between middle and upper third of neck
Palpate paired sternothyrohyoideus muscles and tracheal rings
Give 10ml LA (eg mepivacaine) into skin and underlying tissues
Aseptically prepare site
Make a 6-8cm incision on ventral midline of neck
Palpate the two tracheal rings in the centre of the incision
Make a stab incision between the two rings
Extend the incision for 1-2cm each side of the midline
Insert tracheotomy tube
Secure in place
Give some differential diagnoses for dysphagia
Oesophageal obstruction Retropharyngeal abscess (eg strangles) Retropharyngeal mass (neoplasias, granuloma) Pharyngeal foreign body Gutteral pouch mycosis Equine grass sickness URT infection
Onchocerca cervicalis are found where?
Nuchal ligament
nematode
How big are pinworms?
2-13mm
What is the proper name for pinworm?
Oxyuris equi
What is urticaria?
Raised itchy rash
Wheals, oedema and pruritus
Sweet itch is caused by what?
Where on the horse is it seen?
Culicoides spp
Dorsal surface of horse: tail, mane, back
What does atopy mean?
Hyperallergic
How do you diagnose atopy?
Intradermal skin testing
What is the difference between scaling and crusting?
Scaling= dry, grey Crusting= yellow, red, brown, wet/damp
What is the difference between erosion and ulceration?
Erosion is superficial (partial loss of epithelial or mucosal surface that heals by resolution)
Ulceration is deeper (full thickness loss of epithelial or mucosal surface which heals by repair ie replacement with fibrous tissue)
Describe pemphigus foliaceus
Rare, autoimmune, horse makes antibodies against its own skin Severe crusting No age or sex predilection Dx: skin biopsy Tx: immunosuppressive drugs Prognosis: guarded
Viral papillomas are seen where?
Muzzle, face, pinna, inguinal area
Describe dermatophilosis congolensis
Gram +, facultative anaerobe, branching filaments on histology
Favourable conditions= skin trauma, wet skin
Thick, parakeratotic crusts (continuous epidermal invasion)
Tx: topical (mild cases), systemic antimicrobials (severe cases)
Bacterial folliculitis is caused by what?
Staphylococcus and streptococcus
Give an antifungal used to treat ringworm?
Miconazole
Describe leukocytoclastic vasculitis
Common, affects non-pigmented areas on distal limb
Results from deposition of immune complexes at vessel wall
Painful
Dx: skin biopsy
Tx: corticosteroids, avoid exposure to light
Describe pastern dermatitis
‘Greasy heel’ syndrome
Very common
Caused by chronic wetting of skin on distal heel
Winter, white limbs
What are warbles?
Larval stages of Hypoderma bovis and lineatum, appear as nodule with a central pore (larvae inside)
Neck and trunk
Often painful
Tx: enlargement of pore to remove central grub
What is an atheroma?
Degeneration of the walls of the arteries caused by accumulated fatty deposits and scar tissue
Leads to restriction of circulation -> thrombosis
What types of skin tumours are present in horses?
Sarcoids
Melanoma
Squamous cell carcinoma
Mast cell tumour
Describe sarcoids
Most common skin tumour in horses
Tumour of fibroblasts
Bovine papillomavirus 1 and 2 are most likely cause
6 clinical presentations: occult, verrucous, nodular, fibroblastic, mixed, malignant
Dx: biopsy
Tx: surgery, immune therapy, cytotoxics,
Where are melanomas usually seen?
Perineum, tail head (near anus), parotid region
How do you treat a melanoma?
Surgical excision, immunotherapy
Where are squamous cell carcinomas usually seen?
Poorly pigmented animals
External genitalia, eyes
Where are mast cell rumours found?
Head
Solitary
Males
How is equine herpes virus spread?
Mainly be respiratory route
Aborted foetus/ membranes/ vaginal discharge are highly contagious
How do large and small strongyles affect the colon?
Large: verminous arteritis, thromboembolic colic
Small: submucosal inflammation
Give some haematological changes associated with parasitism?
Neutrophilia, hypoalbuminaemia, hyperglobulinaemia
NOT eosinophilia
What are the two divisions of equine gastric ulcer syndrome?
Give possible risk factors for each
EGGUS: Equine glandular gastric ulcer syndrome (bother horses mοre, harder to treat). Risk factors= possibly stress, NSAID-related.
ESGUS: Equine squamous gastric ulcer syndrome. Risk factor= acid injury.
What are the signs of EGUS (equine gastric ulcer syndrome)?
Weight loss, poor performance
Selective appetite, slow eating, prefer roughage over grain
Bad/cranky behaviou
Colic very unlikely
What is the pH in the two parts of the stomach?
Squamous portion prone to acid injury: pH 5.4
Glandular, acid-secreting portion protected from acid injury by mucous layer: 1.8
Where do ESGUS and EGGUS usually occur?
ESGUS: Caused by ‘splashing’ of stomach acid onto the unprotected mucosal lining above the margo plicatus, on squamous portion of stomach
EGGUS: below margo plicatus on glandular portion of stomach, when protective lining breaks down, exposing the mucosa to acids
Why is the horse so susceptible to gastric ulcers?
Stomach anatomy -> poor mixing of food, grain portion is rapidly fermentable -> acid production
Give some predisposing factors to acid injury leading to gastric ulcers
High concentrate diets -> volatile fatty acids and indirect acid injury via gastrin production in response to absorbed CHO (carbohydrates)
Also, low fibre concentrations -> reduced saliva production (saliva is an acid buffer)
Exercise -> gastrin production, also increased abdominal pressure can promote ‘splashing’ of acid onto unprotected squamous portion
How do you diagnose gastric ulcers?
Gastroscopy - 3m endoscope
Why is a faecal occult blood test not reliable for diagnosing gastric ulcers?
False negatives
How do you treat gastric ulcers?
Omeprazole (proton pump inhibitor)
- Buffered
- Enteric coated
- Plain
EGGUS requires higher doses
Give some clinical signs of colic in order of increasing severity
Flank watching Lying down Pawing the ground Rolling Repeatedly getting up and down Violent thrashing around
Give the different classifications of colic
Spasmodic Impactions Gas distension Obstructions (simple/ strangulating) Non-strangulating infarction Inflammation (enteritis/ colitis) Idiopathic
How do severe cases of colic lead to shock?
Loss of vascular supply to mucosa
Absorption of endotoxins into the circulation
Systemic inflammatory response system (SIRS)
What percentage of colic cases require surgery?
7%
What initial advice should you give to an owner of a horse with suspected colic?
Put horse in a well bedded stable
Remove anything it could injure itself on (buckets, feed etc)
Let horse roll if it wants to
A short period (10 mins) of walking exercise is fine but nothing longer before seeing a vet
Which sedative should you give to a horse with colic when examining it?
Xylazine iv (200mg for a 500kg horse) Also gives analgesia
Which questions should you ask a horse owner when investigating colic?
Which signs were observed?
When did these start/ when was the horse last normal?
Feed intake and faecal output over last 24 hours
Any diarrhoea?
History of equine grass sickness on premises?
Which structures are identifiable during a rectal palpation?
Pelvic flexure Caecum Spleen Nephrosplenic space Small (descending) colon Inguinal rings
What are some common findings when doing a rectal exam to investigate colic?
Distended SI Pelvic flexure impaction Left dorsal displacement Right dorsal displacement Large colon torsion Caecal impaction Small colon impaction
What sized needle should you use when doing an abdominocentesis?
18g, 1.5 inch
What is the appearance of normal peritoneal fluid?
Clear, straw-coloured
Regarding peritoneal fluid, what are the normal values for:
Total protein
WBCC
Lactate
Total protein:
What is the normal packed cell volume of a horse?
35-45%
What is the normal value for systemic total protein?
60-70g/L
Which diagnostic tests should you do when investigating colic?
Haematology (systemic lactate, WBC, systemic TP) Rectal exam Abdominocentesis Nasogastric intubation Ultrasound
What is the most common cause of colic in the foal?
Meconium impaction
What is the medical term for equine grass sickness?
Equine dysautonomia
What is the suspected cause of equine grass sickness?
Clostridium botulinum type C (exists in soil)
Acute, subacute, and chronic forms
Affects autonomic nervous system -> reduced GI motility
Causes a paralytic ileus (obstruction of ileum)
Patchy sweating, tachycardia
Fatal
What are the functions of the upper airways?
Channel for conveying airflow to and from lung
Filtering and conditioning of inspired air
Protection of lower airway from aspiration
Olfaction
Phonation
Swallowing
Thermoregulation
Why is a normal upper airway so critical in a horse in particular?
Because the horse is an obligate nasal breather
What is the tidal volume of a horse at rest?
5L
What is meant by tidal volume?
Lung volume, representing the normal volume of air displaced between normal inhalation and exhalation
What is the minute ventilation of a horse at rest and during exercise?
Rest: 75L
Exercise: 1500L (20x increase)
How do you work out minute ventilation?
Tidal volume x resp rate
Give some clinical signs of upper airway disease
Nasal discharge
Respiratory distress
Exercise intolerance
Noise at exercise
When investigating URT disease, what should you look out for regarding nasal discharge?
Is it unilateral/bilateral? Chronicity Nature of discharge (blood/purulent/serous/food material) Recent head trauma? Recent URT infection? Is it associated with exercise? Any cough/ resp noise? Any facial swelling? Any response to treatment?
When investigating URT disease, what should you look out for regarding respiratory noise?
When does it occur (rest/ exercise?)
If it occurs at exercise, what pace does it occur at?
Is the noise inspiratory/ expiratory/ both?
What does it sound like? (Whistle, roar, gurgle, snoring)
Continuous/ intermittent?
If at exercise, does the horse stop/ slow down when it occurs?
Does the noise disappear once the horse’s speed reduces?
Does the noise limit the horse’s performance?
Does the horse recover normally after exercise?
When doing a clinical exam of the head, what should you look for?
Symmetry Nasal/ocular discharge Airflow from both nostrils Percussion of sinuses Palpation of larynx Evidence of previous surgical scars
In RLN (recurrent laryngeal neuropathy- roaring), which Cricoarytenoideus dorsalis muscle is atrophied?
Left
How can you determine whether a noise made at exercise is made during inspiration or expiration?
Expiration occurs as the leading leg hits the ground at canter and gallop
Is ‘roaring’ heard during inspiration or expiration?
Inspiration
Does dorsal displacement of the soft palate causes respiratory noises during inspiration or expiration?
Both:
Expiration= loud
Inspiration= soft gurgling
Give some causes of abnormal respiratory noises heard at exercise
RLN (recurrent laryngeal neuropathy) DDSP Epiglottic entrapment Subepiglottic cyst Epiglottic retroversion 4-BAD (fourth branchial arch defect) Alar fold collapse/ nasal paralysis ADAF (axial deviation of the aryepiglottic folds)
Which structures you examine with an endoscopy when investigating abnormal respiratory noises?
Nasal passages Sinus drainage angles Ethmoturbinates Nasopharynx Larynx Gutteral pouches
What is the only way of identifying causes of URT obstruction that only occur at exercise?
Exercise endoscopy (High speed treadmill endoscopy= gold standard Can also use dynamic respiratory endoscope-attaches to bridle)
How can you tell if a nasal obstruction is present above or below the nasal septum?
Rostral to nasal septum=unilateral discharge
Above nasal septum=bilateral discharge
When doing radiography, the latero-lateral view is good for assessing which structures?
Paranasal sinuses, gutteral pouches and pharynx
When doing radiography, lateral oblique views are good for assessing which structures?
Peri-apical regions of the premolars and molars (prevents superimposition)
When doing radiography, the dorso-ventral view is good for assessing which structures?
Paranasal sinuses, nasal septum and teeth
Helps to decode of lesions are unilateral or bilateral
Why might you perform a sinoscopy?
Investigate suspected paranasal sinus disease
Obtain material for biopsy
Treatment
Which diagnostic techniques might you use to investigate suspected masses?
MRI
CT scan
What is scintigraphy?
Radio isotopes are administered IV
The emitted radiation is measured by external detectors to produce 2D images
When might you use scintigraphy?
Investigation of orthopaedic disease (eg fracture identification)
Suspected TMJ disease
Identification of damaged tooth
Differentiation between primary and secondary sinusitis
How can you investigate alar folds collapse?
Temporary suture across bridge of nose, if resolves, alar folds collapse is cause of problem
Which bone separates the left and right nasal passages?
Nasal septum and vomer bone
The nasal passages are divided into which 3 sections?
Dorsal, middle, ventral meatus
What are the clinical signs of a problem with the nasal passages?
Nasal discharge Halitosis Abnormal respiratory noise Coughing Facial distortion Head shaking
How can you diagnose problems with the nasal passages?
Radiography
Ultrasound
CT scan
What is wry nose?
Congenital shortening of maxilla, nasal and vomer bones
Causes laterally deviated rostral maxilla and associated nasal septum deviation
Nasal obstruction
Usually accompanied by malocclusion of the teeth
Give some causes of disease in the nasal passages
Trauma Wry nose Deviation or thickening of the nasal septum Neoplasia (carcinoma) Progressive ethmoidal haematoma Fungal infection
When placing an nasogastric tube, which meatus should it pass through?
Ventral (less likely to damage ethmoturbinates)
Use lubricant on end of tube, don’t force it when you hit resistance
What is an ethmoid haematoma?
Encapsulated non-neoplastic mass
Grows into the nasal passages/paranasal sinuses
Unknown aetiology
What are the clinical signs of an ethmoid haematoma?
Mild intermittent unilateral epistaxis
Occasionally abnormal resp noise at exercise
+/- bad smell
How can you diagnose an ethmoid haematoma?
Endoscopy +/- radiography
CT scan
How do you treat an ethmoid haematoma?
Lesions in the nasal passages can be treated with intra-lesional formalin (causes aggressive necrosis of haematoma), however there is potential damage to sinus lining
Laser removal
Surgical removal
Recurrence common
What are the clinical signs of fungal rhinitis (nasal aspergillosis)?
How do you diagnose and treat it?
Unilateral purulent/ occasionally haemorrhagic nasal discharge
Foul smell
Occasionally nasal stertor
Diagnosis: endoscopy
Treatment: removal of fungal plaques and necrotic bone Topical treatment (nystatin powder)
Name the seven pairs of paranasal sinuses
Rostral maxillary Caudal maxillary Frontal Dorsal conchal Ventral conchal Sphenopalatine Ethmoid
How does drainage of sinuses occur?
Gravity and mucociliary action
Where do the other sinuses (apart from rostral maxillary and ventral conchal sinuses) drain?
Into the caudal maxillary sinus -> Middle meatus via the nasomaxillary aperture
What are the clinical signs of paranasal sinus disease?
Unilateral/bilateral nasal discharge (serous/purulent/mucopurulent/ occasionally haemorrhagic)
+/- facial swelling
+/- decreased nasal airflow (depending on amount of secondary oedema)
Fluid lines within a sinus on a radiograph indicate what?
Sinusitis
What is the difference between primary and secondary sinusitis?
Primary: usually results from previous resp tract infection, most commonly infection by streptococcus spp
Secondary: to bother condition, primarily dental disease die to the proximity of the alveolar bone to the maxillary sinuses (08, 09, 10, 11)
How do you treat primary sinusitis?
Rule out strep equi var equi (strangles)
Place on antibiotics eg trimethoprim sulphonamides for 7-14 days
Feed from the ground to encourage drainage
Dust-free management
Turnout as much as possible
Which structure may obstruct the drainage angle of the ventral conchal sinus?
Maxillary septal bulla
How may you surgically approach the paranasal sinuses?
Trephination or bone flap
How do you treat sinusitis that is secondary to peri-apical tooth infection?
Remove affected tooth
Flush sinuses
How do you treat sinusitis that is secondary to a facial fracture?
Remove/stabilise bone fragments
Flush sinuses
Give some clinical signs associated with paranasal sinus cysts
Facial swelling
Reduced nasal airflow
Nasal discharge
Nasal stertor
How do you treat a paranasal sinus cyst?
Surgical removal
What is suturitis?
Periostitis of the suture lines between the nasal and frontal bones
Bilateral firm non-painful swellings in the nasofrontal region
Usually regress with time
What are the two main functions of the pharynx?
Deliver air from the nasal cavity to the larynx
Provides a pathway for food from the oral cavity to the oesophagus
What separates the nasopharynx from the oropharynx?
Soft palate
Why does the pharynx have the potential to collapse during exercise?
Lacks rigid support by bone/cartilage
How does the pharynx retain stability?
Coordinated neuromuscular function
Which nerves innervate the pharynx?
Mandibular branch of trigeminal
Pharyngeal branch of vagus
Hypoglossal
Cervical nerves
What are the main functions of the larynx?
Breathing (communication between pharynx and trachea)
Protect lower airway (prevent inhalation of food during swallowing)
Phonation/ vocalisation
Which cartilages make up the larynx?
Cricoid cartilage
Thyroid cartilage
Epiglottis
Paired arytenoid cartilages
Which muscle is the principle abductor of the glottis?
Cricoarytenoideus dorsalis
Which muscle is the principle adductor of the glottis?
Cricoarytenoidalis lateralis
When does the glottis open and close?
Open: exercise
Close: swallowing
Describe the slap test
Used to diagnose left recurrent laryngeal neuropathy (roaring)
Involves slapping one hemithorax to cause a reflex adduction of the muscular process of the arytenoid cartilage on the opposite side
Which diagnostic techniques can be used to examine the larynx and pharynx?
Endoscopy- exercise and at rest
Radiography
Ultrasound
Give some clinical signs associated with problems with the pharynx
Poor performance Respiratory noise Dysphagia (difficulty swallowing) Nasal discharge Coughing Respiratory distress
Give some diseases associated with the pharynx
Cleft palate Pharyngeal lymphoid hyperplasia DDSP (dorsal displacement of soft palate, can be persistent or intermittent) Palatal instability Pharyngeal collapse Pharyngeal mass Foreign body
When does intermittent dorsal displacement of the soft palate tend to occur?
What happens?
Intense exercise
Soft palate displaces dorsally resulting in an expiratory obstruction
Is intermittent or persistent dorsal displacement of the soft palate often secondary to other disease?
Persistent
Eg epiglottic entrapment, sub-epiglottic ulcer, sub-epiglottic cyst
Give some clinical signs of dorsal displacement of the soft palate
Exercise intolerance
Gurgling/vibrating noise
Rider reports ‘choking/swallowing its tongue’
How can you diagnose DDSP (dorsal displacement of soft palate)?
Endoscopy: resting (limited value) and during exercise (gold standard)
What is the function of thyrohyoideus?
Draws pharynx and larynx rostrally
What is a ‘tie-back’ procedure?
Operation to resolve roaring
Arytenoid cartilage is pulled to the side and sutured to keep it from interfering with airflow
What causes intermittent dorsal displacement of soft palate (IDDSP)?
Neuromuscular dysfunction:
- Pharyngeal branch of vagus nerve/Hypoglossal
- Thyrohyoideus
- Alteration in laryngohyoid position
- Inflammation
Which conservative treatment could you use to treat intermittent dorsal displacement of soft palate (IDDSP)?
Get horses fit
Change tack
Treat inflammatory conditions of the pharynx and gutteral pouch
Try throat support device?
How can you surgically treat dorsal displacement of the soft palate?
Staphylectomy: partial soft palate resection
Myectomy: removal of some of the extrinsic muscles of the larynx, reduced caudal retraction of the larynx
Induction of palatal fibrosis: thermal/laser cautery, stiffens soft palate
Tie forward: BEST, sutures placed between basihyoid bone and thyroid cartilage, positions larynx more rostrally and dorsally
How would you identify a foal with cleft palate?
Milk at nostril
What clinical signs are seen with laryngeal problems?
Respiratory noise Poor performance Dysphagia Coughing Respiratory distress
Explain recurrent laryngeal neuropathy
Common, large breeds
Unilateral paralysis of the left arytenoid cartilage
Progressive loss of myelinated nerve fibres in the left recurrent laryngeal nerve
Atrophy of cricoarytenoidalis dorsalis muscle
Loss of abductor and adductor function
How do you diagnose RLN (recurrent laryngeal neuropathy)?
Abnormal inspiratory noise at exercise - roaring
Poor performance
Clinical exam: +/- atrophy of CAD, negative result on slap test
Endoscopy at rest: asses synchrony of movement, ability to achieve and maintain full abduction (grade 1-4: Havemeyer scale)
Dynamic endoscopy is gold standard to asses degree of collapse during exercise
Describe the 4 grades of the Havemeyer scale when grading RLN (recurrent laryngeal neuropathy)
I: all arytenoid cartilage movements are synchronous and symmetrical. Full arytenoid abduction can be achieved and maintained.
II: arytenoid cartilage movements are asynchronous but full abduction can be achieved and maintained (sub-grades: 1.Transient 2.Permanent)
III. arytenoid cartilage movements are asynchronous and/or asymmetric. Full arytenoid abduction cannot be achieved and maintained (1.Occasions of symmetrical abduction 2.Obvious asymmetry 3.Marked but not total asymmetry)
IV. Complete immobility of the arytenoid cartilage and vocal fold
How can you treat RLN (recurrent laryngeal neuropathy)?
Ventriculectomy
Laryngoplasty (‘tie back’)
Describe a ventriculectomy procedure
Used to treat RLN (recurrent laryngeal neuropathy)
‘Hob day’ procedure
Roaring burr used to every left or both ventricles, which are then excised
+/- vocal cord removed at same time
Describe a ‘tie-back’ procedure
Used to treat RLN (recurrent laryngeal neuropathy)
Suture placed between dorsocaudal edge of cricoid cartilage and muscular process of arytenoid cartilage
Mimics the action of CAD (Cricoarytenoideus dorsalis)
Results in permanent abduction of left arytenoid cartilage
Give some complications of tie-back procedures
Failure Dysphagia Aspiration Persistent cough Infection
Give some causes of laryngeal paralysis (besides RLN)
Gutteral pouch disease
Peripheral neuropathy (eg liver disease)
Organophosphate poisoning
Fourth branchial arch arch defect (4BAD) affects which side of the larynx?
Right side
Explain fourth branchial arch defect
Variable development of the right laryngeal cartilage
Right-sided asymmetry
Rostral displacement of palatopharyngeal arch
Variable ability to abduct right arytenoid cartilage
What is vocal cord collapse (VCC) associated with?
ADAF
Axial deviation of aryepiglottic folds
Describe arytenoid chondritis
Mucosal ulceration
Infection of arytenoid cartilage
Progressive
Respiratory obstruction (younger TB, older mares)
What are the gutteral pouches?
Air-filled mucosa-lined outpouchings of the auditory tubes connecting the nasopharynx to the middle ear
Present in horses but no other domestic species
Paired
350ml in volume
Which structures border the gutteral pouches?
Dorsal: base of skull, first cervical vertebra, tympanic bulla, auditory meatus
Medial: median septum, rectus and longus capitis muscles
Ventral: nasopharynx, retropharyngeal lymph nodes
Lateral: parotid and mandibular salivary glands, Pterygoid muscles
How are gutteral pouches separated?
Separated into a medial and lateral compartment by the stylohyoid bone
Medial is bigger than lateral
Where do gutteral pouches empty?
Nasopharynx via a funnel-shaped orifice that has a fibrocartilage flap
Internal and external carotid arteries supply which compartment of gutteral pouches?
Internal: medial compartment
External: lateral compartment
What are the clinical signs of gutteral pouch disease?
Epistaxis Swelling/dyspnoea Nasal discharge Nerve dysfunction -dysphagia -laryngeal paralysis -Horner's syndrome (constructed pupil) -facial asymmetry
Give some diseases associated with gutteral pouches
Mycosis
Empyema/chondroids
Tympany
Otitis interna/media
Stylohyoid bone: temporohyoid osteopathy, fracture of petrous temporal/basisphenoid
Rupture of longus capitus ‘strap’ muscle
Neoplasia/cysts/foreign bodies
Describe gutteral pouch mycosis
Primary fungal plaque forms over vessels (most commonly internal carotid)
Uncommon but potentially life-threatening
What are the clinical signs of gutteral pouch mycosis?
Nasal discharge
Epistaxis
+/- nerve dysfunction: dysphagia, Horners (pupil constriction), laryngeal paralysis
How do you diagnose gutteral pouch mycosis?
Endoscopy
How do you treat gutteral pouch mycosis?
Surgical occlusion of affected artery: simple ligation (back flow from circle of Willis), or balloon catheterisation, or coil embolisation
Medical management if no history of bleeding: antifungals
Describe gutteral pouch empyema
Purulent material (chondroids) within one or both gutteral pouches
Usually in young horses
Aetiology: URT infection, irritant drugs
What are the clinical signs of gutteral pouch empyema?
Intermittent nasal discharge Parotid swelling and pain Extended head carriage Respiratory noise at rest Difficulty eating and swallowing Occasionally pharyngeal and laryngeal paresis
How do you diagnose gutteral pouch chondroids?
Radiography (increase radiodensity-whiteness- of gutteral pouches on lateral views
Endoscopy (dorsal pharyngeal compression, purulent material in gutteral pouches)
How do you treat chondroids?
Flushing of gutteral pouches using catheters inserted via sinus ostia (small openings connecting sinus to nasal pharynx)
Endoscopic removal of chondroids
Surgical flushing and removal of material
Describe gutteral pouch tympany
Foals Usually unilateral Marked retropharyngeal swelling Clinical signs of: swelling, resp stridor, dysphagia Confirmed on radiography or endoscopy
Describe temporohyoid osteoarthropathy
Progressive disease of the middle ear and bones of the temporohyoid joint (stylohyoid bone, squamous portion of temporal bone)
Aetiology: Middle or inner ear infection
What are the clinical signs of temporohyoid osteoarthropathy?
Early: head shaking, ear rubbing, behavioural chane
Chronic: facial nerve paralysis, head tilt, ataxia, nystagmus (toward affected side)
What are the ‘strap’ muscles?
Longus capitus
Rectus capitus ventralis
Rectus capitus lateralis
Why may the ‘strap’ neck muscles rupture?
Trauma
Usually due to rearing and falling over backwards
Which clinical signs are associated with rupture of the ‘strap’ muscles?
Profuse bilateral epistaxis Ataxia Head tilt Pharyngeal and tracheal compression and secondary upper airway obstruction
How do you diagnose rupture of the neck ‘strap’ muscles?
Endoscopy: roof of pharynx collapsed, normal vessels, swollen muscle bellies
Radiography: fluid lines within gutteral pouch
What is the treatment for rupture of the neck ‘strap’ muscles?
Stall rest
Dependent on degree of concurrent brain trauma or skull fracture
Anti-inflammatories
Supportive care
When is a tracheotomy carried out?
Emergency bypass of URT obstruction
Route for intubation
Rest the URT
Bypass inoperable URT obstruction
How would you perform an emergency tracheotomy?
Clip a 20 x 10cm area on ventral midline at junction between middle and upper third of neck
Palpate paired sternothyrohyoideus muscles and tracheal rings
Give 10ml LA (eg mepivacaine) into skin and underlying tissues
Aseptically prepare site
Make a 6-8cm incision on ventral midline of neck
Palpate the two tracheal rings in the centre of the incision
Make a stab incision between the two rings
Extend the incision for 1-2cm each side of the midline
Insert tracheotomy tube
Secure in place
Give some differential diagnoses for dysphagia
Oesophageal obstruction Retropharyngeal abscess (eg strangles) Retropharyngeal mass (neoplasias, granuloma) Pharyngeal foreign body Gutteral pouch mycosis Equine grass sickness URT infection
Onchocerca cervicalis are found where?
Nuchal ligament
nematode
How big are pinworms?
2-13mm
What is the proper name for pinworm?
Oxyuris equi
What is urticaria?
Raised itchy rash
Wheals, oedema and pruritus
Sweet itch is caused by what?
Where on the horse is it seen?
Culicoides spp
Dorsal surface of horse: tail, mane, back
What does atopy mean?
Hyperallergic
How do you diagnose atopy?
Intradermal skin testing
What is the difference between scaling and crusting?
Scaling= dry, grey Crusting= yellow, red, brown, wet/damp
What is the difference between erosion and ulceration?
Erosion is superficial (partial loss of epithelial or mucosal surface that heals by resolution)
Ulceration is deeper (full thickness loss of epithelial or mucosal surface which heals by repair ie replacement with fibrous tissue)
Describe pemphigus foliaceus
Rare, autoimmune, horse makes antibodies against its own skin Severe crusting No age or sex predilection Dx: skin biopsy Tx: immunosuppressive drugs Prognosis: guarded
Viral papillomas are seen where?
Muzzle, face, pinna, inguinal area
Describe dermatophilosis congolensis
Gram +, facultative anaerobe, branching filaments on histology
Favourable conditions= skin trauma, wet skin
Thick, parakeratotic crusts (continuous epidermal invasion)
Tx: topical (mild cases), systemic antimicrobials (severe cases)
Bacterial folliculitis is caused by what?
Staphylococcus and streptococcus
Give an antifungal used to treat ringworm?
Miconazole
Describe leukocytoclastic vasculitis
Common, affects non-pigmented areas on distal limb
Results from deposition of immune complexes at vessel wall
Painful
Dx: skin biopsy
Tx: corticosteroids, avoid exposure to light
Describe pastern dermatitis
‘Greasy heel’ syndrome
Very common
Caused by chronic wetting of skin on distal heel
Winter, white limbs
What are warbles?
Larval stages of Hypoderma bovis and lineatum, appear as nodule with a central pore (larvae inside)
Neck and trunk
Often painful
Tx: enlargement of pore to remove central grub
What is an atheroma?
Degeneration of the walls of the arteries caused by accumulated fatty deposits and scar tissue
Leads to restriction of circulation -> thrombosis
What types of skin tumours are present in horses?
Sarcoids
Melanoma
Squamous cell carcinoma
Mast cell tumour
Describe sarcoids
Most common skin tumour in horses
Tumour of fibroblasts
Bovine papillomavirus 1 and 2 are most likely cause
6 clinical presentations: occult, verrucous, nodular, fibroblastic, mixed, malignant
Dx: biopsy
Tx: surgery, immune therapy, cytotoxics,
Where are melanomas usually seen?
Perineum, tail head (near anus), parotid region
How do you treat a melanoma?
Surgical excision, immunotherapy
Where are squamous cell carcinomas usually seen?
Poorly pigmented animals
External genitalia, eyes
Where are mast cell rumours found?
Head
Solitary
Males
How is equine herpes virus spread?
Mainly be respiratory route
Aborted foetus/ membranes/ vaginal discharge are highly contagious
How do large and small strongyles affect the colon?
Large: verminous arteritis, thromboembolic colic
Small: submucosal inflammation
Give some haematological changes associated with parasitism?
Neutrophilia, hypoalbuminaemia, hyperglobulinaemia
NOT eosinophilia
What are the two divisions of equine gastric ulcer syndrome?
Give possible risk factors for each
EGGUS: Equine glandular gastric ulcer syndrome (bother horses mοre, harder to treat). Risk factors= possibly stress, NSAID-related.
ESGUS: Equine squamous gastric ulcer syndrome. Risk factor= acid injury.
What are the signs of EGUS (equine gastric ulcer syndrome)?
Weight loss, poor performance
Selective appetite, slow eating, prefer roughage over grain
Bad/cranky behaviou
Colic very unlikely
What is the pH in the two parts of the stomach?
Squamous portion prone to acid injury: pH 5.4
Glandular, acid-secreting portion protected from acid injury by mucous layer: 1.8
Where do ESGUS and EGGUS usually occur?
ESGUS: Caused by ‘splashing’ of stomach acid onto the unprotected mucosal lining above the margo plicatus, on squamous portion of stomach
EGGUS: below margo plicatus on glandular portion of stomach, when protective lining breaks down, exposing the mucosa to acids
Why is the horse so susceptible to gastric ulcers?
Stomach anatomy -> poor mixing of food, grain portion is rapidly fermentable -> acid production
Give some predisposing factors to acid injury leading to gastric ulcers
High concentrate diets -> volatile fatty acids and indirect acid injury via gastrin production in response to absorbed CHO (carbohydrates)
Also, low fibre concentrations -> reduced saliva production (saliva is an acid buffer)
Exercise -> gastrin production, also increased abdominal pressure can promote ‘splashing’ of acid onto unprotected squamous portion
How do you diagnose gastric ulcers?
Gastroscopy - 3m endoscope
Why is a faecal occult blood test not reliable for diagnosing gastric ulcers?
False negatives
How do you treat gastric ulcers?
Omeprazole (proton pump inhibitor)
- Buffered
- Enteric coated
- Plain
EGGUS requires higher doses
Give some clinical signs of colic in order of increasing severity
Flank watching Lying down Pawing the ground Rolling Repeatedly getting up and down Violent thrashing around
Give the different classifications of colic
Spasmodic Impactions Gas distension Obstructions (simple/ strangulating) Non-strangulating infarction Inflammation (enteritis/ colitis) Idiopathic
How do severe cases of colic lead to shock?
Loss of vascular supply to mucosa
Absorption of endotoxins into the circulation
Systemic inflammatory response system (SIRS)
What percentage of colic cases require surgery?
7%
What initial advice should you give to an owner of a horse with suspected colic?
Put horse in a well bedded stable
Remove anything it could injure itself on (buckets, feed etc)
Let horse roll if it wants to
A short period (10 mins) of walking exercise is fine but nothing longer before seeing a vet
Which sedative should you give to a horse with colic when examining it?
Xylazine iv (200mg for a 500kg horse) Also gives analgesia
Which questions should you ask a horse owner when investigating colic?
Which signs were observed?
When did these start/ when was the horse last normal?
Feed intake and faecal output over last 24 hours
Any diarrhoea?
History of equine grass sickness on premises?
Which structures are identifiable during a rectal palpation?
Pelvic flexure Caecum Spleen Nephrosplenic space Small (descending) colon Inguinal rings
What are some common findings when doing a rectal exam to investigate colic?
Distended SI Pelvic flexure impaction Left dorsal displacement Right dorsal displacement Large colon torsion Caecal impaction Small colon impaction
What sized needle should you use when doing an abdominocentesis?
18g, 1.5 inch
What is the appearance of normal peritoneal fluid?
Clear, straw-coloured
Regarding peritoneal fluid, what are the normal values for:
Total protein
WBCC
Lactate
Total protein:
What is the normal packed cell volume of a horse?
35-45%
What is the normal value for systemic total protein?
60-70g/L
Which diagnostic tests should you do when investigating colic?
Haematology (systemic lactate, WBC, systemic TP) Rectal exam Abdominocentesis Nasogastric intubation Ultrasound
What is the most common cause of colic in the foal?
Meconium impaction
What is the medical term for equine grass sickness?
Equine dysautonomia
What is the suspected cause of equine grass sickness?
Clostridium botulinum type C (exists in soil)
Acute, subacute, and chronic forms
Affects autonomic nervous system -> reduced GI motility
Causes a paralytic ileus (obstruction of ileum)
Patchy sweating, tachycardia
Fatal
What are the functions of the upper airways?
Channel for conveying airflow to and from lung
Filtering and conditioning of inspired air
Protection of lower airway from aspiration
Olfaction
Phonation
Swallowing
Thermoregulation
Why is a normal upper airway so critical in a horse in particular?
Because the horse is an obligate nasal breather
What is the tidal volume of a horse at rest?
5L
What is meant by tidal volume?
Lung volume, representing the normal volume of air displaced between normal inhalation and exhalation
What is the minute ventilation of a horse at rest and during exercise?
Rest: 75L
Exercise: 1500L (20x increase)
How do you work out minute ventilation?
Tidal volume x resp rate
Give some clinical signs of upper airway disease
Nasal discharge
Respiratory distress
Exercise intolerance
Noise at exercise
When investigating URT disease, what should you look out for regarding nasal discharge?
Is it unilateral/bilateral? Chronicity Nature of discharge (blood/purulent/serous/food material) Recent head trauma? Recent URT infection? Is it associated with exercise? Any cough/ resp noise? Any facial swelling? Any response to treatment?
When investigating URT disease, what should you look out for regarding respiratory noise?
When does it occur (rest/ exercise?)
If it occurs at exercise, what pace does it occur at?
Is the noise inspiratory/ expiratory/ both?
What does it sound like? (Whistle, roar, gurgle, snoring)
Continuous/ intermittent?
If at exercise, does the horse stop/ slow down when it occurs?
Does the noise disappear once the horse’s speed reduces?
Does the noise limit the horse’s performance?
Does the horse recover normally after exercise?
When doing a clinical exam of the head, what should you look for?
Symmetry Nasal/ocular discharge Airflow from both nostrils Percussion of sinuses Palpation of larynx Evidence of previous surgical scars
In RLN (recurrent laryngeal neuropathy- roaring), which Cricoarytenoideus dorsalis muscle is atrophied?
Left
How can you determine whether a noise made at exercise is made during inspiration or expiration?
Expiration occurs as the leading leg hits the ground at canter and gallop
Is ‘roaring’ heard during inspiration or expiration?
Inspiration
Does dorsal displacement of the soft palate causes respiratory noises during inspiration or expiration?
Both:
Expiration= loud
Inspiration= soft gurgling
Give some causes of abnormal respiratory noises heard at exercise
RLN (recurrent laryngeal neuropathy) DDSP Epiglottic entrapment Subepiglottic cyst Epiglottic retroversion 4-BAD (fourth branchial arch defect) Alar fold collapse/ nasal paralysis ADAF (axial deviation of the aryepiglottic folds)
Which structures you examine with an endoscopy when investigating abnormal respiratory noises?
Nasal passages Sinus drainage angles Ethmoturbinates Nasopharynx Larynx Gutteral pouches
What is the only way of identifying causes of URT obstruction that only occur at exercise?
Exercise endoscopy (High speed treadmill endoscopy= gold standard Can also use dynamic respiratory endoscope-attaches to bridle)
How can you tell if a nasal obstruction is present above or below the nasal septum?
Rostral to nasal septum=unilateral discharge
Above nasal septum=bilateral discharge
When doing radiography, the latero-lateral view is good for assessing which structures?
Paranasal sinuses, gutteral pouches and pharynx
When doing radiography, lateral oblique views are good for assessing which structures?
Peri-apical regions of the premolars and molars (prevents superimposition)
When doing radiography, the dorso-ventral view is good for assessing which structures?
Paranasal sinuses, nasal septum and teeth
Helps to decode of lesions are unilateral or bilateral
Why might you perform a sinoscopy?
Investigate suspected paranasal sinus disease
Obtain material for biopsy
Treatment
Which diagnostic techniques might you use to investigate suspected masses?
MRI
CT scan
What is scintigraphy?
Radio isotopes are administered IV
The emitted radiation is measured by external detectors to produce 2D images
When might you use scintigraphy?
Investigation of orthopaedic disease (eg fracture identification)
Suspected TMJ disease
Identification of damaged tooth
Differentiation between primary and secondary sinusitis
How can you investigate alar folds collapse?
Temporary suture across bridge of nose, if resolves, alar folds collapse is cause of problem
Which bone separates the left and right nasal passages?
Nasal septum and vomer bone
The nasal passages are divided into which 3 sections?
Dorsal, middle, ventral meatus
What are the clinical signs of a problem with the nasal passages?
Nasal discharge Halitosis Abnormal respiratory noise Coughing Facial distortion Head shaking
How can you diagnose problems with the nasal passages?
Radiography
Ultrasound
CT scan
What is wry nose?
Congenital shortening of maxilla, nasal and vomer bones
Causes laterally deviated rostral maxilla and associated nasal septum deviation
Nasal obstruction
Usually accompanied by malocclusion of the teeth
Give some causes of disease in the nasal passages
Trauma Wry nose Deviation or thickening of the nasal septum Neoplasia (carcinoma) Progressive ethmoidal haematoma Fungal infection
When placing an nasogastric tube, which meatus should it pass through?
Ventral (less likely to damage ethmoturbinates)
Use lubricant on end of tube, don’t force it when you hit resistance
What is an ethmoid haematoma?
Encapsulated non-neoplastic mass
Grows into the nasal passages/paranasal sinuses
Unknown aetiology
What are the clinical signs of an ethmoid haematoma?
Mild intermittent unilateral epistaxis
Occasionally abnormal resp noise at exercise
+/- bad smell
How can you diagnose an ethmoid haematoma?
Endoscopy +/- radiography
CT scan
How do you treat an ethmoid haematoma?
Lesions in the nasal passages can be treated with intra-lesional formalin (causes aggressive necrosis of haematoma), however there is potential damage to sinus lining
Laser removal
Surgical removal
Recurrence common
What are the clinical signs of fungal rhinitis (nasal aspergillosis)?
How do you diagnose and treat it?
Unilateral purulent/ occasionally haemorrhagic nasal discharge
Foul smell
Occasionally nasal stertor
Diagnosis: endoscopy
Treatment: removal of fungal plaques and necrotic bone Topical treatment (nystatin powder)
Name the seven pairs of paranasal sinuses
Rostral maxillary Caudal maxillary Frontal Dorsal conchal Ventral conchal Sphenopalatine Ethmoid
How does drainage of sinuses occur?
Gravity and mucociliary action
Where do the other sinuses (apart from rostral maxillary and ventral conchal sinuses) drain?
Into the caudal maxillary sinus -> Middle meatus via the nasomaxillary aperture
What are the clinical signs of paranasal sinus disease?
Unilateral/bilateral nasal discharge (serous/purulent/mucopurulent/ occasionally haemorrhagic)
+/- facial swelling
+/- decreased nasal airflow (depending on amount of secondary oedema)
Fluid lines within a sinus on a radiograph indicate what?
Sinusitis
What is the difference between primary and secondary sinusitis?
Primary: usually results from previous resp tract infection, most commonly infection by streptococcus spp
Secondary: to bother condition, primarily dental disease die to the proximity of the alveolar bone to the maxillary sinuses (08, 09, 10, 11)
How do you treat primary sinusitis?
Rule out strep equi var equi (strangles)
Place on antibiotics eg trimethoprim sulphonamides for 7-14 days
Feed from the ground to encourage drainage
Dust-free management
Turnout as much as possible
Which structure may obstruct the drainage angle of the ventral conchal sinus?
Maxillary septal bulla
How may you surgically approach the paranasal sinuses?
Trephination or bone flap
How do you treat sinusitis that is secondary to peri-apical tooth infection?
Remove affected tooth
Flush sinuses
How do you treat sinusitis that is secondary to a facial fracture?
Remove/stabilise bone fragments
Flush sinuses
Give some clinical signs associated with paranasal sinus cysts
Facial swelling
Reduced nasal airflow
Nasal discharge
Nasal stertor
How do you treat a paranasal sinus cyst?
Surgical removal
What is suturitis?
Periostitis of the suture lines between the nasal and frontal bones
Bilateral firm non-painful swellings in the nasofrontal region
Usually regress with time
What are the two main functions of the pharynx?
Deliver air from the nasal cavity to the larynx
Provides a pathway for food from the oral cavity to the oesophagus
What separates the nasopharynx from the oropharynx?
Soft palate
Why does the pharynx have the potential to collapse during exercise?
Lacks rigid support by bone/cartilage
How does the pharynx retain stability?
Coordinated neuromuscular function
Which nerves innervate the pharynx?
Mandibular branch of trigeminal
Pharyngeal branch of vagus
Hypoglossal
Cervical nerves
What are the main functions of the larynx?
Breathing (communication between pharynx and trachea)
Protect lower airway (prevent inhalation of food during swallowing)
Phonation/ vocalisation
Which cartilages make up the larynx?
Cricoid cartilage
Thyroid cartilage
Epiglottis
Paired arytenoid cartilages
Which muscle is the principle abductor of the glottis?
Cricoarytenoideus dorsalis
Which muscle is the principle adductor of the glottis?
Cricoarytenoidalis lateralis
When does the glottis open and close?
Open: exercise
Close: swallowing
Describe the slap test
Used to diagnose left recurrent laryngeal neuropathy (roaring)
Involves slapping one hemithorax to cause a reflex adduction of the muscular process of the arytenoid cartilage on the opposite side
Which diagnostic techniques can be used to examine the larynx and pharynx?
Endoscopy- exercise and at rest
Radiography
Ultrasound
Give some clinical signs associated with problems with the pharynx
Poor performance Respiratory noise Dysphagia (difficulty swallowing) Nasal discharge Coughing Respiratory distress
Give some diseases associated with the pharynx
Cleft palate Pharyngeal lymphoid hyperplasia DDSP (dorsal displacement of soft palate, can be persistent or intermittent) Palatal instability Pharyngeal collapse Pharyngeal mass Foreign body
When does intermittent dorsal displacement of the soft palate tend to occur?
What happens?
Intense exercise
Soft palate displaces dorsally resulting in an expiratory obstruction
Is intermittent or persistent dorsal displacement of the soft palate often secondary to other disease?
Persistent
Eg epiglottic entrapment, sub-epiglottic ulcer, sub-epiglottic cyst
Give some clinical signs of dorsal displacement of the soft palate
Exercise intolerance
Gurgling/vibrating noise
Rider reports ‘choking/swallowing its tongue’
How can you diagnose DDSP (dorsal displacement of soft palate)?
Endoscopy: resting (limited value) and during exercise (gold standard)
What is the function of thyrohyoideus?
Draws pharynx and larynx rostrally
What is a ‘tie-back’ procedure?
Operation to resolve roaring
Arytenoid cartilage is pulled to the side and sutured to keep it from interfering with airflow
What causes intermittent dorsal displacement of soft palate (IDDSP)?
Neuromuscular dysfunction:
- Pharyngeal branch of vagus nerve/Hypoglossal
- Thyrohyoideus
- Alteration in laryngohyoid position
- Inflammation
Which conservative treatment could you use to treat intermittent dorsal displacement of soft palate (IDDSP)?
Get horses fit
Change tack
Treat inflammatory conditions of the pharynx and gutteral pouch
Try throat support device?
How can you surgically treat dorsal displacement of the soft palate?
Staphylectomy: partial soft palate resection
Myectomy: removal of some of the extrinsic muscles of the larynx, reduced caudal retraction of the larynx
Induction of palatal fibrosis: thermal/laser cautery, stiffens soft palate
Tie forward: BEST, sutures placed between basihyoid bone and thyroid cartilage, positions larynx more rostrally and dorsally
How would you identify a foal with cleft palate?
Milk at nostril
What clinical signs are seen with laryngeal problems?
Respiratory noise Poor performance Dysphagia Coughing Respiratory distress
Explain recurrent laryngeal neuropathy
Common, large breeds
Unilateral paralysis of the left arytenoid cartilage
Progressive loss of myelinated nerve fibres in the left recurrent laryngeal nerve
Atrophy of cricoarytenoidalis dorsalis muscle
Loss of abductor and adductor function
How do you diagnose RLN (recurrent laryngeal neuropathy)?
Abnormal inspiratory noise at exercise - roaring
Poor performance
Clinical exam: +/- atrophy of CAD, negative result on slap test
Endoscopy at rest: asses synchrony of movement, ability to achieve and maintain full abduction (grade 1-4: Havemeyer scale)
Dynamic endoscopy is gold standard to asses degree of collapse during exercise
Describe the 4 grades of the Havemeyer scale when grading RLN (recurrent laryngeal neuropathy)
I: all arytenoid cartilage movements are synchronous and symmetrical. Full arytenoid abduction can be achieved and maintained.
II: arytenoid cartilage movements are asynchronous but full abduction can be achieved and maintained (sub-grades: 1.Transient 2.Permanent)
III. arytenoid cartilage movements are asynchronous and/or asymmetric. Full arytenoid abduction cannot be achieved and maintained (1.Occasions of symmetrical abduction 2.Obvious asymmetry 3.Marked but not total asymmetry)
IV. Complete immobility of the arytenoid cartilage and vocal fold
How can you treat RLN (recurrent laryngeal neuropathy)?
Ventriculectomy
Laryngoplasty (‘tie back’)
Describe a ventriculectomy procedure
Used to treat RLN (recurrent laryngeal neuropathy)
‘Hob day’ procedure
Roaring burr used to every left or both ventricles, which are then excised
+/- vocal cord removed at same time
Describe a ‘tie-back’ procedure
Used to treat RLN (recurrent laryngeal neuropathy)
Suture placed between dorsocaudal edge of cricoid cartilage and muscular process of arytenoid cartilage
Mimics the action of CAD (Cricoarytenoideus dorsalis)
Results in permanent abduction of left arytenoid cartilage
Give some complications of tie-back procedures
Failure Dysphagia Aspiration Persistent cough Infection
Give some causes of laryngeal paralysis (besides RLN)
Gutteral pouch disease
Peripheral neuropathy (eg liver disease)
Organophosphate poisoning
Fourth branchial arch arch defect (4BAD) affects which side of the larynx?
Right side
Explain fourth branchial arch defect
Variable development of the right laryngeal cartilage
Right-sided asymmetry
Rostral displacement of palatopharyngeal arch
Variable ability to abduct right arytenoid cartilage
What is vocal cord collapse (VCC) associated with?
ADAF
Axial deviation of aryepiglottic folds
Describe arytenoid chondritis
Mucosal ulceration
Infection of arytenoid cartilage
Progressive
Respiratory obstruction (younger TB, older mares)
What are the gutteral pouches?
Air-filled mucosa-lined outpouchings of the auditory tubes connecting the nasopharynx to the middle ear
Present in horses but no other domestic species
Paired
350ml in volume
Which structures border the gutteral pouches?
Dorsal: base of skull, first cervical vertebra, tympanic bulla, auditory meatus
Medial: median septum, rectus and longus capitis muscles
Ventral: nasopharynx, retropharyngeal lymph nodes
Lateral: parotid and mandibular salivary glands, Pterygoid muscles
How are gutteral pouches separated?
Separated into a medial and lateral compartment by the stylohyoid bone
Medial is bigger than lateral
Where do gutteral pouches empty?
Nasopharynx via a funnel-shaped orifice that has a fibrocartilage flap
Internal and external carotid arteries supply which compartment of gutteral pouches?
Internal: medial compartment
External: lateral compartment
What are the clinical signs of gutteral pouch disease?
Epistaxis Swelling/dyspnoea Nasal discharge Nerve dysfunction -dysphagia -laryngeal paralysis -Horner's syndrome (constructed pupil) -facial asymmetry
Give some diseases associated with gutteral pouches
Mycosis
Empyema/chondroids
Tympany
Otitis interna/media
Stylohyoid bone: temporohyoid osteopathy, fracture of petrous temporal/basisphenoid
Rupture of longus capitus ‘strap’ muscle
Neoplasia/cysts/foreign bodies
Describe gutteral pouch mycosis
Primary fungal plaque forms over vessels (most commonly internal carotid)
Uncommon but potentially life-threatening
What are the clinical signs of gutteral pouch mycosis?
Nasal discharge
Epistaxis
+/- nerve dysfunction: dysphagia, Horners (pupil constriction), laryngeal paralysis
How do you diagnose gutteral pouch mycosis?
Endoscopy
How do you treat gutteral pouch mycosis?
Surgical occlusion of affected artery: simple ligation (back flow from circle of Willis), or balloon catheterisation, or coil embolisation
Medical management if no history of bleeding: antifungals
Describe gutteral pouch empyema
Purulent material (chondroids) within one or both gutteral pouches
Usually in young horses
Aetiology: URT infection, irritant drugs
What are the clinical signs of gutteral pouch empyema?
Intermittent nasal discharge Parotid swelling and pain Extended head carriage Respiratory noise at rest Difficulty eating and swallowing Occasionally pharyngeal and laryngeal paresis
How do you diagnose gutteral pouch chondroids?
Radiography (increase radiodensity-whiteness- of gutteral pouches on lateral views
Endoscopy (dorsal pharyngeal compression, purulent material in gutteral pouches)
How do you treat chondroids?
Flushing of gutteral pouches using catheters inserted via sinus ostia (small openings connecting sinus to nasal pharynx)
Endoscopic removal of chondroids
Surgical flushing and removal of material
Describe gutteral pouch tympany
Foals Usually unilateral Marked retropharyngeal swelling Clinical signs of: swelling, resp stridor, dysphagia Confirmed on radiography or endoscopy
Describe temporohyoid osteoarthropathy
Progressive disease of the middle ear and bones of the temporohyoid joint (stylohyoid bone, squamous portion of temporal bone)
Aetiology: Middle or inner ear infection
What are the clinical signs of temporohyoid osteoarthropathy?
Early: head shaking, ear rubbing, behavioural chane
Chronic: facial nerve paralysis, head tilt, ataxia, nystagmus (toward affected side)
What are the ‘strap’ muscles?
Longus capitus
Rectus capitus ventralis
Rectus capitus lateralis
Why may the ‘strap’ neck muscles rupture?
Trauma
Usually due to rearing and falling over backwards
Which clinical signs are associated with rupture of the ‘strap’ muscles?
Profuse bilateral epistaxis Ataxia Head tilt Pharyngeal and tracheal compression and secondary upper airway obstruction
How do you diagnose rupture of the neck ‘strap’ muscles?
Endoscopy: roof of pharynx collapsed, normal vessels, swollen muscle bellies
Radiography: fluid lines within gutteral pouch
What is the treatment for rupture of the neck ‘strap’ muscles?
Stall rest
Dependent on degree of concurrent brain trauma or skull fracture
Anti-inflammatories
Supportive care
When is a tracheotomy carried out?
Emergency bypass of URT obstruction
Route for intubation
Rest the URT
Bypass inoperable URT obstruction
How would you perform an emergency tracheotomy?
Clip a 20 x 10cm area on ventral midline at junction between middle and upper third of neck
Palpate paired sternothyrohyoideus muscles and tracheal rings
Give 10ml LA (eg mepivacaine) into skin and underlying tissues
Aseptically prepare site
Make a 6-8cm incision on ventral midline of neck
Palpate the two tracheal rings in the centre of the incision
Make a stab incision between the two rings
Extend the incision for 1-2cm each side of the midline
Insert tracheotomy tube
Secure in place
Give some differential diagnoses for dysphagia
Oesophageal obstruction Retropharyngeal abscess (eg strangles) Retropharyngeal mass (neoplasias, granuloma) Pharyngeal foreign body Gutteral pouch mycosis Equine grass sickness URT infection
Onchocerca cervicalis are found where?
Nuchal ligament
nematode
How big are pinworms?
2-13mm
What is the proper name for pinworm?
Oxyuris equi
What is urticaria?
Raised itchy rash
Wheals, oedema and pruritus
Sweet itch is caused by what?
Where on the horse is it seen?
Culicoides spp
Dorsal surface of horse: tail, mane, back
What does atopy mean?
Hyperallergic
How do you diagnose atopy?
Intradermal skin testing
What is the difference between scaling and crusting?
Scaling= dry, grey Crusting= yellow, red, brown, wet/damp
What is the difference between erosion and ulceration?
Erosion is superficial (partial loss of epithelial or mucosal surface that heals by resolution)
Ulceration is deeper (full thickness loss of epithelial or mucosal surface which heals by repair ie replacement with fibrous tissue)
Describe pemphigus foliaceus
Rare, autoimmune, horse makes antibodies against its own skin Severe crusting No age or sex predilection Dx: skin biopsy Tx: immunosuppressive drugs Prognosis: guarded
Viral papillomas are seen where?
Muzzle, face, pinna, inguinal area
Describe dermatophilosis congolensis
Gram +, facultative anaerobe, branching filaments on histology
Favourable conditions= skin trauma, wet skin
Thick, parakeratotic crusts (continuous epidermal invasion)
Tx: topical (mild cases), systemic antimicrobials (severe cases)
Bacterial folliculitis is caused by what?
Staphylococcus and streptococcus
Give an antifungal used to treat ringworm?
Miconazole
Describe leukocytoclastic vasculitis
Common, affects non-pigmented areas on distal limb
Results from deposition of immune complexes at vessel wall
Painful
Dx: skin biopsy
Tx: corticosteroids, avoid exposure to light
Describe pastern dermatitis
‘Greasy heel’ syndrome
Very common
Caused by chronic wetting of skin on distal heel
Winter, white limbs
What are warbles?
Larval stages of Hypoderma bovis and lineatum, appear as nodule with a central pore (larvae inside)
Neck and trunk
Often painful
Tx: enlargement of pore to remove central grub
What is an atheroma?
Degeneration of the walls of the arteries caused by accumulated fatty deposits and scar tissue
Leads to restriction of circulation -> thrombosis
What types of skin tumours are present in horses?
Sarcoids
Melanoma
Squamous cell carcinoma
Mast cell tumour
Describe sarcoids
Most common skin tumour in horses
Tumour of fibroblasts
Bovine papillomavirus 1 and 2 are most likely cause
6 clinical presentations: occult, verrucous, nodular, fibroblastic, mixed, malignant
Dx: biopsy
Tx: surgery, immune therapy, cytotoxics,
Where are melanomas usually seen?
Perineum, tail head (near anus), parotid region
How do you treat a melanoma?
Surgical excision, immunotherapy
Where are squamous cell carcinomas usually seen?
Poorly pigmented animals
External genitalia, eyes
Where are mast cell rumours found?
Head
Solitary
Males
How is equine herpes virus spread?
Mainly be respiratory route
Aborted foetus/ membranes/ vaginal discharge are highly contagious
How do large and small strongyles affect the colon?
Large: verminous arteritis, thromboembolic colic
Small: submucosal inflammation
Give some haematological changes associated with parasitism?
Neutrophilia, hypoalbuminaemia, hyperglobulinaemia
NOT eosinophilia
What are the two divisions of equine gastric ulcer syndrome?
Give possible risk factors for each
EGGUS: Equine glandular gastric ulcer syndrome (bother horses mοre, harder to treat). Risk factors= possibly stress, NSAID-related.
ESGUS: Equine squamous gastric ulcer syndrome. Risk factor= acid injury.
What are the signs of EGUS (equine gastric ulcer syndrome)?
Weight loss, poor performance
Selective appetite, slow eating, prefer roughage over grain
Bad/cranky behaviou
Colic very unlikely
What is the pH in the two parts of the stomach?
Squamous portion prone to acid injury: pH 5.4
Glandular, acid-secreting portion protected from acid injury by mucous layer: 1.8
Where do ESGUS and EGGUS usually occur?
ESGUS: Caused by ‘splashing’ of stomach acid onto the unprotected mucosal lining above the margo plicatus, on squamous portion of stomach
EGGUS: below margo plicatus on glandular portion of stomach, when protective lining breaks down, exposing the mucosa to acids
Why is the horse so susceptible to gastric ulcers?
Stomach anatomy -> poor mixing of food, grain portion is rapidly fermentable -> acid production
Give some predisposing factors to acid injury leading to gastric ulcers
High concentrate diets -> volatile fatty acids and indirect acid injury via gastrin production in response to absorbed CHO (carbohydrates)
Also, low fibre concentrations -> reduced saliva production (saliva is an acid buffer)
Exercise -> gastrin production, also increased abdominal pressure can promote ‘splashing’ of acid onto unprotected squamous portion
How do you diagnose gastric ulcers?
Gastroscopy - 3m endoscope
Why is a faecal occult blood test not reliable for diagnosing gastric ulcers?
False negatives
How do you treat gastric ulcers?
Omeprazole (proton pump inhibitor)
- Buffered
- Enteric coated
- Plain
EGGUS requires higher doses
Give some clinical signs of colic in order of increasing severity
Flank watching Lying down Pawing the ground Rolling Repeatedly getting up and down Violent thrashing around
Give the different classifications of colic
Spasmodic Impactions Gas distension Obstructions (simple/ strangulating) Non-strangulating infarction Inflammation (enteritis/ colitis) Idiopathic
How do severe cases of colic lead to shock?
Loss of vascular supply to mucosa
Absorption of endotoxins into the circulation
Systemic inflammatory response system (SIRS)
What percentage of colic cases require surgery?
7%
What initial advice should you give to an owner of a horse with suspected colic?
Put horse in a well bedded stable
Remove anything it could injure itself on (buckets, feed etc)
Let horse roll if it wants to
A short period (10 mins) of walking exercise is fine but nothing longer before seeing a vet
Which sedative should you give to a horse with colic when examining it?
Xylazine iv (200mg for a 500kg horse) Also gives analgesia
Which questions should you ask a horse owner when investigating colic?
Which signs were observed?
When did these start/ when was the horse last normal?
Feed intake and faecal output over last 24 hours
Any diarrhoea?
History of equine grass sickness on premises?
Which structures are identifiable during a rectal palpation?
Pelvic flexure Caecum Spleen Nephrosplenic space Small (descending) colon Inguinal rings
What are some common findings when doing a rectal exam to investigate colic?
Distended SI Pelvic flexure impaction Left dorsal displacement Right dorsal displacement Large colon torsion Caecal impaction Small colon impaction
What sized needle should you use when doing an abdominocentesis?
18g, 1.5 inch
What is the appearance of normal peritoneal fluid?
Clear, straw-coloured
Regarding peritoneal fluid, what are the normal values for:
Total protein
WBCC
Lactate
Total protein:
What is the normal packed cell volume of a horse?
35-45%
What is the normal value for systemic total protein?
60-70g/L
Which diagnostic tests should you do when investigating colic?
Haematology (systemic lactate, WBC, systemic TP) Rectal exam Abdominocentesis Nasogastric intubation Ultrasound
What is the most common cause of colic in the foal?
Meconium impaction
What is the medical term for equine grass sickness?
Equine dysautonomia
What is the suspected cause of equine grass sickness?
Clostridium botulinum type C (exists in soil)
Acute, subacute, and chronic forms
Affects autonomic nervous system -> reduced GI motility
Causes a paralytic ileus (obstruction of ileum)
Patchy sweating, tachycardia
Fatal
What are the functions of the upper airways?
Channel for conveying airflow to and from lung
Filtering and conditioning of inspired air
Protection of lower airway from aspiration
Olfaction
Phonation
Swallowing
Thermoregulation
Why is a normal upper airway so critical in a horse in particular?
Because the horse is an obligate nasal breather
What is the tidal volume of a horse at rest?
5L
What is meant by tidal volume?
Lung volume, representing the normal volume of air displaced between normal inhalation and exhalation
What is the minute ventilation of a horse at rest and during exercise?
Rest: 75L
Exercise: 1500L (20x increase)
How do you work out minute ventilation?
Tidal volume x resp rate
Give some clinical signs of upper airway disease
Nasal discharge
Respiratory distress
Exercise intolerance
Noise at exercise
When investigating URT disease, what should you look out for regarding nasal discharge?
Is it unilateral/bilateral? Chronicity Nature of discharge (blood/purulent/serous/food material) Recent head trauma? Recent URT infection? Is it associated with exercise? Any cough/ resp noise? Any facial swelling? Any response to treatment?
When investigating URT disease, what should you look out for regarding respiratory noise?
When does it occur (rest/ exercise?)
If it occurs at exercise, what pace does it occur at?
Is the noise inspiratory/ expiratory/ both?
What does it sound like? (Whistle, roar, gurgle, snoring)
Continuous/ intermittent?
If at exercise, does the horse stop/ slow down when it occurs?
Does the noise disappear once the horse’s speed reduces?
Does the noise limit the horse’s performance?
Does the horse recover normally after exercise?
When doing a clinical exam of the head, what should you look for?
Symmetry Nasal/ocular discharge Airflow from both nostrils Percussion of sinuses Palpation of larynx Evidence of previous surgical scars
In RLN (recurrent laryngeal neuropathy- roaring), which Cricoarytenoideus dorsalis muscle is atrophied?
Left
How can you determine whether a noise made at exercise is made during inspiration or expiration?
Expiration occurs as the leading leg hits the ground at canter and gallop
Is ‘roaring’ heard during inspiration or expiration?
Inspiration
Does dorsal displacement of the soft palate causes respiratory noises during inspiration or expiration?
Both:
Expiration= loud
Inspiration= soft gurgling
Give some causes of abnormal respiratory noises heard at exercise
RLN (recurrent laryngeal neuropathy) DDSP Epiglottic entrapment Subepiglottic cyst Epiglottic retroversion 4-BAD (fourth branchial arch defect) Alar fold collapse/ nasal paralysis ADAF (axial deviation of the aryepiglottic folds)
Which structures you examine with an endoscopy when investigating abnormal respiratory noises?
Nasal passages Sinus drainage angles Ethmoturbinates Nasopharynx Larynx Gutteral pouches
What is the only way of identifying causes of URT obstruction that only occur at exercise?
Exercise endoscopy (High speed treadmill endoscopy= gold standard Can also use dynamic respiratory endoscope-attaches to bridle)
How can you tell if a nasal obstruction is present above or below the nasal septum?
Rostral to nasal septum=unilateral discharge
Above nasal septum=bilateral discharge
When doing radiography, the latero-lateral view is good for assessing which structures?
Paranasal sinuses, gutteral pouches and pharynx
When doing radiography, lateral oblique views are good for assessing which structures?
Peri-apical regions of the premolars and molars (prevents superimposition)
When doing radiography, the dorso-ventral view is good for assessing which structures?
Paranasal sinuses, nasal septum and teeth
Helps to decode of lesions are unilateral or bilateral
Why might you perform a sinoscopy?
Investigate suspected paranasal sinus disease
Obtain material for biopsy
Treatment
Which diagnostic techniques might you use to investigate suspected masses?
MRI
CT scan
What is scintigraphy?
Radio isotopes are administered IV
The emitted radiation is measured by external detectors to produce 2D images
When might you use scintigraphy?
Investigation of orthopaedic disease (eg fracture identification)
Suspected TMJ disease
Identification of damaged tooth
Differentiation between primary and secondary sinusitis
How can you investigate alar folds collapse?
Temporary suture across bridge of nose, if resolves, alar folds collapse is cause of problem
Which bone separates the left and right nasal passages?
Nasal septum and vomer bone
The nasal passages are divided into which 3 sections?
Dorsal, middle, ventral meatus
What are the clinical signs of a problem with the nasal passages?
Nasal discharge Halitosis Abnormal respiratory noise Coughing Facial distortion Head shaking
How can you diagnose problems with the nasal passages?
Radiography
Ultrasound
CT scan
What is wry nose?
Congenital shortening of maxilla, nasal and vomer bones
Causes laterally deviated rostral maxilla and associated nasal septum deviation
Nasal obstruction
Usually accompanied by malocclusion of the teeth
Give some causes of disease in the nasal passages
Trauma Wry nose Deviation or thickening of the nasal septum Neoplasia (carcinoma) Progressive ethmoidal haematoma Fungal infection
When placing an nasogastric tube, which meatus should it pass through?
Ventral (less likely to damage ethmoturbinates)
Use lubricant on end of tube, don’t force it when you hit resistance
What is an ethmoid haematoma?
Encapsulated non-neoplastic mass
Grows into the nasal passages/paranasal sinuses
Unknown aetiology
What are the clinical signs of an ethmoid haematoma?
Mild intermittent unilateral epistaxis
Occasionally abnormal resp noise at exercise
+/- bad smell
How can you diagnose an ethmoid haematoma?
Endoscopy +/- radiography
CT scan
How do you treat an ethmoid haematoma?
Lesions in the nasal passages can be treated with intra-lesional formalin (causes aggressive necrosis of haematoma), however there is potential damage to sinus lining
Laser removal
Surgical removal
Recurrence common
What are the clinical signs of fungal rhinitis (nasal aspergillosis)?
How do you diagnose and treat it?
Unilateral purulent/ occasionally haemorrhagic nasal discharge
Foul smell
Occasionally nasal stertor
Diagnosis: endoscopy
Treatment: removal of fungal plaques and necrotic bone Topical treatment (nystatin powder)
Name the seven pairs of paranasal sinuses
Rostral maxillary Caudal maxillary Frontal Dorsal conchal Ventral conchal Sphenopalatine Ethmoid
How does drainage of sinuses occur?
Gravity and mucociliary action
Where do the other sinuses (apart from rostral maxillary and ventral conchal sinuses) drain?
Into the caudal maxillary sinus -> Middle meatus via the nasomaxillary aperture
What are the clinical signs of paranasal sinus disease?
Unilateral/bilateral nasal discharge (serous/purulent/mucopurulent/ occasionally haemorrhagic)
+/- facial swelling
+/- decreased nasal airflow (depending on amount of secondary oedema)
Fluid lines within a sinus on a radiograph indicate what?
Sinusitis
What is the difference between primary and secondary sinusitis?
Primary: usually results from previous resp tract infection, most commonly infection by streptococcus spp
Secondary: to bother condition, primarily dental disease die to the proximity of the alveolar bone to the maxillary sinuses (08, 09, 10, 11)
How do you treat primary sinusitis?
Rule out strep equi var equi (strangles)
Place on antibiotics eg trimethoprim sulphonamides for 7-14 days
Feed from the ground to encourage drainage
Dust-free management
Turnout as much as possible
Which structure may obstruct the drainage angle of the ventral conchal sinus?
Maxillary septal bulla
How may you surgically approach the paranasal sinuses?
Trephination or bone flap
How do you treat sinusitis that is secondary to peri-apical tooth infection?
Remove affected tooth
Flush sinuses
How do you treat sinusitis that is secondary to a facial fracture?
Remove/stabilise bone fragments
Flush sinuses
Give some clinical signs associated with paranasal sinus cysts
Facial swelling
Reduced nasal airflow
Nasal discharge
Nasal stertor
How do you treat a paranasal sinus cyst?
Surgical removal
What is suturitis?
Periostitis of the suture lines between the nasal and frontal bones
Bilateral firm non-painful swellings in the nasofrontal region
Usually regress with time
What are the two main functions of the pharynx?
Deliver air from the nasal cavity to the larynx
Provides a pathway for food from the oral cavity to the oesophagus
What separates the nasopharynx from the oropharynx?
Soft palate
Why does the pharynx have the potential to collapse during exercise?
Lacks rigid support by bone/cartilage
How does the pharynx retain stability?
Coordinated neuromuscular function
Which nerves innervate the pharynx?
Mandibular branch of trigeminal
Pharyngeal branch of vagus
Hypoglossal
Cervical nerves
What are the main functions of the larynx?
Breathing (communication between pharynx and trachea)
Protect lower airway (prevent inhalation of food during swallowing)
Phonation/ vocalisation
Which cartilages make up the larynx?
Cricoid cartilage
Thyroid cartilage
Epiglottis
Paired arytenoid cartilages
Which muscle is the principle abductor of the glottis?
Cricoarytenoideus dorsalis
Which muscle is the principle adductor of the glottis?
Cricoarytenoidalis lateralis
When does the glottis open and close?
Open: exercise
Close: swallowing
Describe the slap test
Used to diagnose left recurrent laryngeal neuropathy (roaring)
Involves slapping one hemithorax to cause a reflex adduction of the muscular process of the arytenoid cartilage on the opposite side
Which diagnostic techniques can be used to examine the larynx and pharynx?
Endoscopy- exercise and at rest
Radiography
Ultrasound
Give some clinical signs associated with problems with the pharynx
Poor performance Respiratory noise Dysphagia (difficulty swallowing) Nasal discharge Coughing Respiratory distress
Give some diseases associated with the pharynx
Cleft palate Pharyngeal lymphoid hyperplasia DDSP (dorsal displacement of soft palate, can be persistent or intermittent) Palatal instability Pharyngeal collapse Pharyngeal mass Foreign body
When does intermittent dorsal displacement of the soft palate tend to occur?
What happens?
Intense exercise
Soft palate displaces dorsally resulting in an expiratory obstruction
Is intermittent or persistent dorsal displacement of the soft palate often secondary to other disease?
Persistent
Eg epiglottic entrapment, sub-epiglottic ulcer, sub-epiglottic cyst
Give some clinical signs of dorsal displacement of the soft palate
Exercise intolerance
Gurgling/vibrating noise
Rider reports ‘choking/swallowing its tongue’
How can you diagnose DDSP (dorsal displacement of soft palate)?
Endoscopy: resting (limited value) and during exercise (gold standard)
What is the function of thyrohyoideus?
Draws pharynx and larynx rostrally
What is a ‘tie-back’ procedure?
Operation to resolve roaring
Arytenoid cartilage is pulled to the side and sutured to keep it from interfering with airflow
What causes intermittent dorsal displacement of soft palate (IDDSP)?
Neuromuscular dysfunction:
- Pharyngeal branch of vagus nerve/Hypoglossal
- Thyrohyoideus
- Alteration in laryngohyoid position
- Inflammation
Which conservative treatment could you use to treat intermittent dorsal displacement of soft palate (IDDSP)?
Get horses fit
Change tack
Treat inflammatory conditions of the pharynx and gutteral pouch
Try throat support device?
How can you surgically treat dorsal displacement of the soft palate?
Staphylectomy: partial soft palate resection
Myectomy: removal of some of the extrinsic muscles of the larynx, reduced caudal retraction of the larynx
Induction of palatal fibrosis: thermal/laser cautery, stiffens soft palate
Tie forward: BEST, sutures placed between basihyoid bone and thyroid cartilage, positions larynx more rostrally and dorsally
How would you identify a foal with cleft palate?
Milk at nostril
What clinical signs are seen with laryngeal problems?
Respiratory noise Poor performance Dysphagia Coughing Respiratory distress
Explain recurrent laryngeal neuropathy
Common, large breeds
Unilateral paralysis of the left arytenoid cartilage
Progressive loss of myelinated nerve fibres in the left recurrent laryngeal nerve
Atrophy of cricoarytenoidalis dorsalis muscle
Loss of abductor and adductor function
How do you diagnose RLN (recurrent laryngeal neuropathy)?
Abnormal inspiratory noise at exercise - roaring
Poor performance
Clinical exam: +/- atrophy of CAD, negative result on slap test
Endoscopy at rest: asses synchrony of movement, ability to achieve and maintain full abduction (grade 1-4: Havemeyer scale)
Dynamic endoscopy is gold standard to asses degree of collapse during exercise
Describe the 4 grades of the Havemeyer scale when grading RLN (recurrent laryngeal neuropathy)
I: all arytenoid cartilage movements are synchronous and symmetrical. Full arytenoid abduction can be achieved and maintained.
II: arytenoid cartilage movements are asynchronous but full abduction can be achieved and maintained (sub-grades: 1.Transient 2.Permanent)
III. arytenoid cartilage movements are asynchronous and/or asymmetric. Full arytenoid abduction cannot be achieved and maintained (1.Occasions of symmetrical abduction 2.Obvious asymmetry 3.Marked but not total asymmetry)
IV. Complete immobility of the arytenoid cartilage and vocal fold
How can you treat RLN (recurrent laryngeal neuropathy)?
Ventriculectomy
Laryngoplasty (‘tie back’)
Describe a ventriculectomy procedure
Used to treat RLN (recurrent laryngeal neuropathy)
‘Hob day’ procedure
Roaring burr used to every left or both ventricles, which are then excised
+/- vocal cord removed at same time
Describe a ‘tie-back’ procedure
Used to treat RLN (recurrent laryngeal neuropathy)
Suture placed between dorsocaudal edge of cricoid cartilage and muscular process of arytenoid cartilage
Mimics the action of CAD (Cricoarytenoideus dorsalis)
Results in permanent abduction of left arytenoid cartilage
Give some complications of tie-back procedures
Failure Dysphagia Aspiration Persistent cough Infection
Give some causes of laryngeal paralysis (besides RLN)
Gutteral pouch disease
Peripheral neuropathy (eg liver disease)
Organophosphate poisoning
Fourth branchial arch arch defect (4BAD) affects which side of the larynx?
Right side
Explain fourth branchial arch defect
Variable development of the right laryngeal cartilage
Right-sided asymmetry
Rostral displacement of palatopharyngeal arch
Variable ability to abduct right arytenoid cartilage
What is vocal cord collapse (VCC) associated with?
ADAF
Axial deviation of aryepiglottic folds
Describe arytenoid chondritis
Mucosal ulceration
Infection of arytenoid cartilage
Progressive
Respiratory obstruction (younger TB, older mares)
What are the gutteral pouches?
Air-filled mucosa-lined outpouchings of the auditory tubes connecting the nasopharynx to the middle ear
Present in horses but no other domestic species
Paired
350ml in volume
Which structures border the gutteral pouches?
Dorsal: base of skull, first cervical vertebra, tympanic bulla, auditory meatus
Medial: median septum, rectus and longus capitis muscles
Ventral: nasopharynx, retropharyngeal lymph nodes
Lateral: parotid and mandibular salivary glands, Pterygoid muscles
How are gutteral pouches separated?
Separated into a medial and lateral compartment by the stylohyoid bone
Medial is bigger than lateral
Where do gutteral pouches empty?
Nasopharynx via a funnel-shaped orifice that has a fibrocartilage flap
Internal and external carotid arteries supply which compartment of gutteral pouches?
Internal: medial compartment
External: lateral compartment
What are the clinical signs of gutteral pouch disease?
Epistaxis Swelling/dyspnoea Nasal discharge Nerve dysfunction -dysphagia -laryngeal paralysis -Horner's syndrome (constructed pupil) -facial asymmetry
Give some diseases associated with gutteral pouches
Mycosis
Empyema/chondroids
Tympany
Otitis interna/media
Stylohyoid bone: temporohyoid osteopathy, fracture of petrous temporal/basisphenoid
Rupture of longus capitus ‘strap’ muscle
Neoplasia/cysts/foreign bodies
Describe gutteral pouch mycosis
Primary fungal plaque forms over vessels (most commonly internal carotid)
Uncommon but potentially life-threatening
What are the clinical signs of gutteral pouch mycosis?
Nasal discharge
Epistaxis
+/- nerve dysfunction: dysphagia, Horners (pupil constriction), laryngeal paralysis
How do you diagnose gutteral pouch mycosis?
Endoscopy
How do you treat gutteral pouch mycosis?
Surgical occlusion of affected artery: simple ligation (back flow from circle of Willis), or balloon catheterisation, or coil embolisation
Medical management if no history of bleeding: antifungals
Describe gutteral pouch empyema
Purulent material (chondroids) within one or both gutteral pouches
Usually in young horses
Aetiology: URT infection, irritant drugs
What are the clinical signs of gutteral pouch empyema?
Intermittent nasal discharge Parotid swelling and pain Extended head carriage Respiratory noise at rest Difficulty eating and swallowing Occasionally pharyngeal and laryngeal paresis
How do you diagnose gutteral pouch chondroids?
Radiography (increase radiodensity-whiteness- of gutteral pouches on lateral views
Endoscopy (dorsal pharyngeal compression, purulent material in gutteral pouches)
How do you treat chondroids?
Flushing of gutteral pouches using catheters inserted via sinus ostia (small openings connecting sinus to nasal pharynx)
Endoscopic removal of chondroids
Surgical flushing and removal of material
Describe gutteral pouch tympany
Foals Usually unilateral Marked retropharyngeal swelling Clinical signs of: swelling, resp stridor, dysphagia Confirmed on radiography or endoscopy
Describe temporohyoid osteoarthropathy
Progressive disease of the middle ear and bones of the temporohyoid joint (stylohyoid bone, squamous portion of temporal bone)
Aetiology: Middle or inner ear infection
What are the clinical signs of temporohyoid osteoarthropathy?
Early: head shaking, ear rubbing, behavioural chane
Chronic: facial nerve paralysis, head tilt, ataxia, nystagmus (toward affected side)
What are the ‘strap’ muscles?
Longus capitus
Rectus capitus ventralis
Rectus capitus lateralis
Why may the ‘strap’ neck muscles rupture?
Trauma
Usually due to rearing and falling over backwards
Which clinical signs are associated with rupture of the ‘strap’ muscles?
Profuse bilateral epistaxis Ataxia Head tilt Pharyngeal and tracheal compression and secondary upper airway obstruction
How do you diagnose rupture of the neck ‘strap’ muscles?
Endoscopy: roof of pharynx collapsed, normal vessels, swollen muscle bellies
Radiography: fluid lines within gutteral pouch
What is the treatment for rupture of the neck ‘strap’ muscles?
Stall rest
Dependent on degree of concurrent brain trauma or skull fracture
Anti-inflammatories
Supportive care
When is a tracheotomy carried out?
Emergency bypass of URT obstruction
Route for intubation
Rest the URT
Bypass inoperable URT obstruction
How would you perform an emergency tracheotomy?
Clip a 20 x 10cm area on ventral midline at junction between middle and upper third of neck
Palpate paired sternothyrohyoideus muscles and tracheal rings
Give 10ml LA (eg mepivacaine) into skin and underlying tissues
Aseptically prepare site
Make a 6-8cm incision on ventral midline of neck
Palpate the two tracheal rings in the centre of the incision
Make a stab incision between the two rings
Extend the incision for 1-2cm each side of the midline
Insert tracheotomy tube
Secure in place
Give some differential diagnoses for dysphagia
Oesophageal obstruction Retropharyngeal abscess (eg strangles) Retropharyngeal mass (neoplasias, granuloma) Pharyngeal foreign body Gutteral pouch mycosis Equine grass sickness URT infection
Onchocerca cervicalis are found where?
Nuchal ligament
nematode
How big are pinworms?
2-13mm
What is the proper name for pinworm?
Oxyuris equi
What is urticaria?
Raised itchy rash
Wheals, oedema and pruritus
Sweet itch is caused by what?
Where on the horse is it seen?
Culicoides spp
Dorsal surface of horse: tail, mane, back
What does atopy mean?
Hyperallergic
How do you diagnose atopy?
Intradermal skin testing
What is the difference between scaling and crusting?
Scaling= dry, grey Crusting= yellow, red, brown, wet/damp
What is the difference between erosion and ulceration?
Erosion is superficial (partial loss of epithelial or mucosal surface that heals by resolution)
Ulceration is deeper (full thickness loss of epithelial or mucosal surface which heals by repair ie replacement with fibrous tissue)
Describe pemphigus foliaceus
Rare, autoimmune, horse makes antibodies against its own skin Severe crusting No age or sex predilection Dx: skin biopsy Tx: immunosuppressive drugs Prognosis: guarded
Viral papillomas are seen where?
Muzzle, face, pinna, inguinal area
Describe dermatophilosis congolensis
Gram +, facultative anaerobe, branching filaments on histology
Favourable conditions= skin trauma, wet skin
Thick, parakeratotic crusts (continuous epidermal invasion)
Tx: topical (mild cases), systemic antimicrobials (severe cases)
Bacterial folliculitis is caused by what?
Staphylococcus and streptococcus
Give an antifungal used to treat ringworm?
Miconazole
Describe leukocytoclastic vasculitis
Common, affects non-pigmented areas on distal limb
Results from deposition of immune complexes at vessel wall
Painful
Dx: skin biopsy
Tx: corticosteroids, avoid exposure to light
Describe pastern dermatitis
‘Greasy heel’ syndrome
Very common
Caused by chronic wetting of skin on distal heel
Winter, white limbs
What are warbles?
Larval stages of Hypoderma bovis and lineatum, appear as nodule with a central pore (larvae inside)
Neck and trunk
Often painful
Tx: enlargement of pore to remove central grub
What is an atheroma?
Degeneration of the walls of the arteries caused by accumulated fatty deposits and scar tissue
Leads to restriction of circulation -> thrombosis
What types of skin tumours are present in horses?
Sarcoids
Melanoma
Squamous cell carcinoma
Mast cell tumour
Describe sarcoids
Most common skin tumour in horses
Tumour of fibroblasts
Bovine papillomavirus 1 and 2 are most likely cause
6 clinical presentations: occult, verrucous, nodular, fibroblastic, mixed, malignant
Dx: biopsy
Tx: surgery, immune therapy, cytotoxics,
Where are melanomas usually seen?
Perineum, tail head (near anus), parotid region
How do you treat a melanoma?
Surgical excision, immunotherapy
Where are squamous cell carcinomas usually seen?
Poorly pigmented animals
External genitalia, eyes
Where are mast cell rumours found?
Head
Solitary
Males
How is equine herpes virus spread?
Mainly be respiratory route
Aborted foetus/ membranes/ vaginal discharge are highly contagious
How do large and small strongyles affect the colon?
Large: verminous arteritis, thromboembolic colic
Small: submucosal inflammation
Give some haematological changes associated with parasitism?
Neutrophilia, hypoalbuminaemia, hyperglobulinaemia
NOT eosinophilia
What are the two divisions of equine gastric ulcer syndrome?
Give possible risk factors for each
EGGUS: Equine glandular gastric ulcer syndrome (bother horses mοre, harder to treat). Risk factors= possibly stress, NSAID-related.
ESGUS: Equine squamous gastric ulcer syndrome. Risk factor= acid injury.
What are the signs of EGUS (equine gastric ulcer syndrome)?
Weight loss, poor performance
Selective appetite, slow eating, prefer roughage over grain
Bad/cranky behaviou
Colic very unlikely
What is the pH in the two parts of the stomach?
Squamous portion prone to acid injury: pH 5.4
Glandular, acid-secreting portion protected from acid injury by mucous layer: 1.8
Where do ESGUS and EGGUS usually occur?
ESGUS: Caused by ‘splashing’ of stomach acid onto the unprotected mucosal lining above the margo plicatus, on squamous portion of stomach
EGGUS: below margo plicatus on glandular portion of stomach, when protective lining breaks down, exposing the mucosa to acids
Why is the horse so susceptible to gastric ulcers?
Stomach anatomy -> poor mixing of food, grain portion is rapidly fermentable -> acid production
Give some predisposing factors to acid injury leading to gastric ulcers
High concentrate diets -> volatile fatty acids and indirect acid injury via gastrin production in response to absorbed CHO (carbohydrates)
Also, low fibre concentrations -> reduced saliva production (saliva is an acid buffer)
Exercise -> gastrin production, also increased abdominal pressure can promote ‘splashing’ of acid onto unprotected squamous portion
How do you diagnose gastric ulcers?
Gastroscopy - 3m endoscope
Why is a faecal occult blood test not reliable for diagnosing gastric ulcers?
False negatives
How do you treat gastric ulcers?
Omeprazole (proton pump inhibitor)
- Buffered
- Enteric coated
- Plain
EGGUS requires higher doses
Give some clinical signs of colic in order of increasing severity
Flank watching Lying down Pawing the ground Rolling Repeatedly getting up and down Violent thrashing around
Give the different classifications of colic
Spasmodic Impactions Gas distension Obstructions (simple/ strangulating) Non-strangulating infarction Inflammation (enteritis/ colitis) Idiopathic
How do severe cases of colic lead to shock?
Loss of vascular supply to mucosa
Absorption of endotoxins into the circulation
Systemic inflammatory response system (SIRS)
What percentage of colic cases require surgery?
7%
What initial advice should you give to an owner of a horse with suspected colic?
Put horse in a well bedded stable
Remove anything it could injure itself on (buckets, feed etc)
Let horse roll if it wants to
A short period (10 mins) of walking exercise is fine but nothing longer before seeing a vet
Which sedative should you give to a horse with colic when examining it?
Xylazine iv (200mg for a 500kg horse) Also gives analgesia
Which questions should you ask a horse owner when investigating colic?
Which signs were observed?
When did these start/ when was the horse last normal?
Feed intake and faecal output over last 24 hours
Any diarrhoea?
History of equine grass sickness on premises?
Which structures are identifiable during a rectal palpation?
Pelvic flexure Caecum Spleen Nephrosplenic space Small (descending) colon Inguinal rings
What are some common findings when doing a rectal exam to investigate colic?
Distended SI Pelvic flexure impaction Left dorsal displacement Right dorsal displacement Large colon torsion Caecal impaction Small colon impaction
What sized needle should you use when doing an abdominocentesis?
18g, 1.5 inch
What is the appearance of normal peritoneal fluid?
Clear, straw-coloured
Regarding peritoneal fluid, what are the normal values for:
Total protein
WBCC
Lactate
Total protein:
What is the normal packed cell volume of a horse?
35-45%
What is the normal value for systemic total protein?
60-70g/L
Which diagnostic tests should you do when investigating colic?
Haematology (systemic lactate, WBC, systemic TP) Rectal exam Abdominocentesis Nasogastric intubation Ultrasound
What is the most common cause of colic in the foal?
Meconium impaction
What is the medical term for equine grass sickness?
Equine dysautonomia
What is the suspected cause of equine grass sickness?
Clostridium botulinum type C (exists in soil)
Acute, subacute, and chronic forms
Affects autonomic nervous system -> reduced GI motility
Causes a paralytic ileus (obstruction of ileum)
Patchy sweating, tachycardia
Fatal
What are the functions of the upper airways?
Channel for conveying airflow to and from lung
Filtering and conditioning of inspired air
Protection of lower airway from aspiration
Olfaction
Phonation
Swallowing
Thermoregulation
Why is a normal upper airway so critical in a horse in particular?
Because the horse is an obligate nasal breather
What is the tidal volume of a horse at rest?
5L
What is meant by tidal volume?
Lung volume, representing the normal volume of air displaced between normal inhalation and exhalation
What is the minute ventilation of a horse at rest and during exercise?
Rest: 75L
Exercise: 1500L (20x increase)
How do you work out minute ventilation?
Tidal volume x resp rate
Give some clinical signs of upper airway disease
Nasal discharge
Respiratory distress
Exercise intolerance
Noise at exercise
When investigating URT disease, what should you look out for regarding nasal discharge?
Is it unilateral/bilateral? Chronicity Nature of discharge (blood/purulent/serous/food material) Recent head trauma? Recent URT infection? Is it associated with exercise? Any cough/ resp noise? Any facial swelling? Any response to treatment?
When investigating URT disease, what should you look out for regarding respiratory noise?
When does it occur (rest/ exercise?)
If it occurs at exercise, what pace does it occur at?
Is the noise inspiratory/ expiratory/ both?
What does it sound like? (Whistle, roar, gurgle, snoring)
Continuous/ intermittent?
If at exercise, does the horse stop/ slow down when it occurs?
Does the noise disappear once the horse’s speed reduces?
Does the noise limit the horse’s performance?
Does the horse recover normally after exercise?
When doing a clinical exam of the head, what should you look for?
Symmetry Nasal/ocular discharge Airflow from both nostrils Percussion of sinuses Palpation of larynx Evidence of previous surgical scars
In RLN (recurrent laryngeal neuropathy- roaring), which Cricoarytenoideus dorsalis muscle is atrophied?
Left
How can you determine whether a noise made at exercise is made during inspiration or expiration?
Expiration occurs as the leading leg hits the ground at canter and gallop
Is ‘roaring’ heard during inspiration or expiration?
Inspiration
Does dorsal displacement of the soft palate causes respiratory noises during inspiration or expiration?
Both:
Expiration= loud
Inspiration= soft gurgling
Give some causes of abnormal respiratory noises heard at exercise
RLN (recurrent laryngeal neuropathy) DDSP Epiglottic entrapment Subepiglottic cyst Epiglottic retroversion 4-BAD (fourth branchial arch defect) Alar fold collapse/ nasal paralysis ADAF (axial deviation of the aryepiglottic folds)
Which structures you examine with an endoscopy when investigating abnormal respiratory noises?
Nasal passages Sinus drainage angles Ethmoturbinates Nasopharynx Larynx Gutteral pouches
What is the only way of identifying causes of URT obstruction that only occur at exercise?
Exercise endoscopy (High speed treadmill endoscopy= gold standard Can also use dynamic respiratory endoscope-attaches to bridle)
How can you tell if a nasal obstruction is present above or below the nasal septum?
Rostral to nasal septum=unilateral discharge
Above nasal septum=bilateral discharge
When doing radiography, the latero-lateral view is good for assessing which structures?
Paranasal sinuses, gutteral pouches and pharynx
When doing radiography, lateral oblique views are good for assessing which structures?
Peri-apical regions of the premolars and molars (prevents superimposition)
When doing radiography, the dorso-ventral view is good for assessing which structures?
Paranasal sinuses, nasal septum and teeth
Helps to decode of lesions are unilateral or bilateral
Why might you perform a sinoscopy?
Investigate suspected paranasal sinus disease
Obtain material for biopsy
Treatment
Which diagnostic techniques might you use to investigate suspected masses?
MRI
CT scan
What is scintigraphy?
Radio isotopes are administered IV
The emitted radiation is measured by external detectors to produce 2D images
When might you use scintigraphy?
Investigation of orthopaedic disease (eg fracture identification)
Suspected TMJ disease
Identification of damaged tooth
Differentiation between primary and secondary sinusitis
How can you investigate alar folds collapse?
Temporary suture across bridge of nose, if resolves, alar folds collapse is cause of problem
Which bone separates the left and right nasal passages?
Nasal septum and vomer bone
The nasal passages are divided into which 3 sections?
Dorsal, middle, ventral meatus
What are the clinical signs of a problem with the nasal passages?
Nasal discharge Halitosis Abnormal respiratory noise Coughing Facial distortion Head shaking
How can you diagnose problems with the nasal passages?
Radiography
Ultrasound
CT scan
What is wry nose?
Congenital shortening of maxilla, nasal and vomer bones
Causes laterally deviated rostral maxilla and associated nasal septum deviation
Nasal obstruction
Usually accompanied by malocclusion of the teeth
Give some causes of disease in the nasal passages
Trauma Wry nose Deviation or thickening of the nasal septum Neoplasia (carcinoma) Progressive ethmoidal haematoma Fungal infection
When placing an nasogastric tube, which meatus should it pass through?
Ventral (less likely to damage ethmoturbinates)
Use lubricant on end of tube, don’t force it when you hit resistance
What is an ethmoid haematoma?
Encapsulated non-neoplastic mass
Grows into the nasal passages/paranasal sinuses
Unknown aetiology
What are the clinical signs of an ethmoid haematoma?
Mild intermittent unilateral epistaxis
Occasionally abnormal resp noise at exercise
+/- bad smell
How can you diagnose an ethmoid haematoma?
Endoscopy +/- radiography
CT scan
How do you treat an ethmoid haematoma?
Lesions in the nasal passages can be treated with intra-lesional formalin (causes aggressive necrosis of haematoma), however there is potential damage to sinus lining
Laser removal
Surgical removal
Recurrence common
What are the clinical signs of fungal rhinitis (nasal aspergillosis)?
How do you diagnose and treat it?
Unilateral purulent/ occasionally haemorrhagic nasal discharge
Foul smell
Occasionally nasal stertor
Diagnosis: endoscopy
Treatment: removal of fungal plaques and necrotic bone Topical treatment (nystatin powder)
Name the seven pairs of paranasal sinuses
Rostral maxillary Caudal maxillary Frontal Dorsal conchal Ventral conchal Sphenopalatine Ethmoid
How does drainage of sinuses occur?
Gravity and mucociliary action
Where do the other sinuses (apart from rostral maxillary and ventral conchal sinuses) drain?
Into the caudal maxillary sinus -> Middle meatus via the nasomaxillary aperture
What are the clinical signs of paranasal sinus disease?
Unilateral/bilateral nasal discharge (serous/purulent/mucopurulent/ occasionally haemorrhagic)
+/- facial swelling
+/- decreased nasal airflow (depending on amount of secondary oedema)
Fluid lines within a sinus on a radiograph indicate what?
Sinusitis
What is the difference between primary and secondary sinusitis?
Primary: usually results from previous resp tract infection, most commonly infection by streptococcus spp
Secondary: to bother condition, primarily dental disease die to the proximity of the alveolar bone to the maxillary sinuses (08, 09, 10, 11)
How do you treat primary sinusitis?
Rule out strep equi var equi (strangles)
Place on antibiotics eg trimethoprim sulphonamides for 7-14 days
Feed from the ground to encourage drainage
Dust-free management
Turnout as much as possible
Which structure may obstruct the drainage angle of the ventral conchal sinus?
Maxillary septal bulla
How may you surgically approach the paranasal sinuses?
Trephination or bone flap
How do you treat sinusitis that is secondary to peri-apical tooth infection?
Remove affected tooth
Flush sinuses
How do you treat sinusitis that is secondary to a facial fracture?
Remove/stabilise bone fragments
Flush sinuses
Give some clinical signs associated with paranasal sinus cysts
Facial swelling
Reduced nasal airflow
Nasal discharge
Nasal stertor
How do you treat a paranasal sinus cyst?
Surgical removal
What is suturitis?
Periostitis of the suture lines between the nasal and frontal bones
Bilateral firm non-painful swellings in the nasofrontal region
Usually regress with time
What are the two main functions of the pharynx?
Deliver air from the nasal cavity to the larynx
Provides a pathway for food from the oral cavity to the oesophagus
What separates the nasopharynx from the oropharynx?
Soft palate
Why does the pharynx have the potential to collapse during exercise?
Lacks rigid support by bone/cartilage
How does the pharynx retain stability?
Coordinated neuromuscular function
Which nerves innervate the pharynx?
Mandibular branch of trigeminal
Pharyngeal branch of vagus
Hypoglossal
Cervical nerves
What are the main functions of the larynx?
Breathing (communication between pharynx and trachea)
Protect lower airway (prevent inhalation of food during swallowing)
Phonation/ vocalisation
Which cartilages make up the larynx?
Cricoid cartilage
Thyroid cartilage
Epiglottis
Paired arytenoid cartilages
Which muscle is the principle abductor of the glottis?
Cricoarytenoideus dorsalis
