Equine repro Flashcards
How often should urine outflow from the ureters be seen under xylazine sedation by endoscopy?
Every 20-45 seconds
Ruptured bladder in foals - Age? Why happens? Clinical signs?
1-5do (more common in colts) Excessive pressure during parturition on a distended bladder More common ventral Rare in adults Clinical signs: - depression/off suck - progressive abdominal distension - mild/moderate colic - increased frequency of attempted urination and small volumes passed (dysuria esp stranguria)
Diagnosis of a ruptured bladder in foals?
History and presenting signs Biochemistry and haematology - hyperkalaemia - hypo Na and Cl - dehydration - metabolic acidosis - post renal azotaemia Peritoneal fluid analysis - serum:peritoneal fluid creatinine >1:2 - clear fluid with low SG - may be calcium carbonate crystals Ultrasonography \+/- Radiography and contrast studies
Why must a foal with a ruptured bladder be stabilised before GA? How? Treatment?
Hyperkalaemia can cause fatal arrhythmias - K+ must be <5.5 before induction
Rule our concurrent disorders e.g. sepsis
Fluid therapy
- IV saline/Hartmann’s
- +/- sodium bicarbonate
- calcium boroglucoronate (antagonises the adverse myocardial effects of hyperkalaemia by raising threshold potential)
- insulin/glucose (insulin stimulates activation of Na/K ATPase pumps to get K+ back into cells
Abdominal drainage (slow) - reduce K+ and improve ventilation
BUT AVOID BICARBONATE AND INSULIN IN FOALS - USE 0.9% SALINE WITH 5% GLUCOSE
Oxygen therapy
Antibiotics
Check IgG status
SLow drainage of peritoneal fluid
Then surgical repair via midline laparotomy +/- resection of umbilicus and urachus at same time
Urolithiasis in horses - Which horses? Associations? Types? Diagnosis? Treatment?
Uncommon (usually found in bladder)
Adult, male horses
Cystitis
Urinary tract obstruction
2 types of calcium carbonate):
- type I (more common): spiculated stone, yellow/green
- type II: smooth and white, harder and contain more phosphate
Also fabulous urolithiasis - sludge usually secondary to bladder paralysis
Diagnosis:
- history and presenting signs: haematuria, stranguria, +/- pollakuria, pyuria or incontinence
- clinical exam - rectal exam
- ultrasonography
- endoscopy
Treatment:
- surgical removal: laparotomy/laparoscopy
- electro hydraulic/laser lithotripsy
What is sabulous cystitis?
Secondary problem
Consequence to bladder paralysis or other physical or neurologic disorders interfering with complete bladder emptying
When would a nephrectomy be performed in the horse?
Renal neoplasia
Pyelonephritis non responsive to medical treatment
What do the umbilical arteries and vein and urachus become?
Umbilical arteries - lateral ligaments of the bladder
Umbilical vein - round ligament of the liver
Urachus - round ligament of the bladder
What happens normally to the umbilicus in foals? When to investigate?
Umbilical cord breaks naturally immediately after parturition
Should progressively dry up and disappear over 4-6 weeks
Investigate if moistness >24h, swelling/pain on palpation or if febrile
Patent urachus in foals - Why happens? Signs? What to check? Treatment?
Fails to close spontaneously or can reopen if sepsis occurs
Moisture around umbilicus +/- dripping of urine
Check for concurrent septicaemia/septic arthritis or physitis
Assess IgG status
Medical treatment - antibiotics, topical cauterising agents (concentrated phenol or iodine solution or with silver nitrate applicators)
Often self resolving
Surgical - resection of urachus
Umbilical sepsis - Age when seen? Signs? Diagnosis? Treatment?
First 1-2 weeks of life
Foal depressed & off suck
Swollen, painful umbilicus
Diagnosis: ultrasonography of umbilicus
Treatment:
- assess IgG status & assess for concurrent septicaemia/septic arthritis/physitis
- blood culture, haematology & biochemistry
- systemic antibiotics
- surgical resection if no response to therapy/deterioration
Umbilical hernias in horses - Significance? When is surgical repair needed?
Common congenital defect Most are small and resolve with time Determine size and whether reducible or non reducible Surgical repair required if: - large defect that persists > 6mo - defect enlarges - associated with colic
How old is a colt/stallion and filly/mare?
<4 = colt/filly >4 = stallion/mare
When should testes have descended into scrotum in colts?
Normally descend into inguinal canal at 270-300d gestation so normally present at or shortly after birth
If not, may occur up to 24mo
When does puberty of colts and fillies occur? When is maximal sexual maturity reached in stallions? How long do mares cycle for?
12-24mo
Stallions: Maximal sexual maturity reached at 4-5 years and retained until about 20 years
Mares: Cycling continues for rest of life but fertility may decline
Anatomy of the stallion’s penis?
Photos
How long does spermatogenesis take?
60 days
What affects stallion semen quality?
Testicular size
Testicular efficiency - greater % of testicles that is sperm producing = more sperm
Age - younger stallions produce less sperm and run risk of being overworked, production maintained well after full sexual maturity
Season - long day breeders
Frequency of ejaculations - number of sperm halves after each successive ejaculation
General health/injury
Sperm dose required for natural service and AI? Number of mares mated per day?
Natural service - 500 million motile sperm
AI - 150-500 million motile sperm
Some busy stallions may mate up to 6 mares in a day
Where is swabbed for CEM? What causes it?
Urethra, urethral fossal, penile sheath, pre-ejaculatory fluid if available
Taylorella equigenitalis
Equine Viral Arteritis (EVA) - Main problem? Vaccination?
Causes Abortion Stallions become carriers Notifiable in stallions Blood test before vaccination to prove seronegative Artervac vaccine
Treatment for paraphimosis and priapism of stallion?
Paraphimosis (inability to retract penis into prepuce) - support with some kind of truss, maybe give GA roll on back and gently replace penis in sheath and place purse string sutures across preputial orifice
Priapism (persistent erection without sexual excitement) - surgically corrected by flushing corpus cavernosus with heparinised saline under GA, B2 agonist
What specific conditions to check for with stallions with colic?
Inguinal herniation
Scrotal herniation
Testicular torsion
Advantages of AI?
Can be transported - spreading genetic material
Can be stored even after death
Ejaculates can be divided into smaller doses - more matings
Reduces risk of venereal disease
Reduces post mating endometritis
Can be examined readily
Disadvantages of AI?
Specialist skills needed to collect, process and inseminate semen
Conception rates may not equal natural service
Expensive
Labour intensive
Venereal infection still possible
Not acceptable for thoroughbred authorities
Use of semen after collected from stallion?
Fresh - use within few hours, can use extenders (increase lifespan of sperm, may contain antibiotics to kill pathogens, often milk or egg based)
Chilled - can last up to 48h, mixed with extenders and then slowly cooled to 5C
Frozen - separated into small 0.25-5ml doses, treated with extenders and cryoprotectants, frozen in sealed straws, stored in liquid nitrogen flasks, keep forever, warm to 37C in water bath, dried, unsealed and inseminated just through cervix or into uterine horn on side of ovulation
When to serve mares?
Natural, fresh, chilled - up to 48h before ovulation
Frozen - best as close to ovulation as possible as survival time not as long (up to 12h before or 6h after ovulation)
Pre-parturient problems in the mare?
Colic - foal moving, normal GI colic, colonic infarctions/necrosis, uterine torsion
Overlarge mare - ventral oedema, pre-pubic tendon rupture, hydros hydrallantois/hydramnios
Placentitis
Varicose veins
Orthopaedic disease
Intrapartum problems in the mare?
Dystocia Uterine rupture Uterine tear Cervical tear Perineal tear
Post-parturient problems in the mare?
Colic - uterine cramps, normal GI colic, uterine haemorrhage, colonic torsion, uterine horn inversion, colonic infarctions/necrosis Prolapse - uterus, rectum RFM Metritis Hypocalcaemia Tetanus Cervical tears Perineal lacerations Uterine rupture Invagination/retroflexion of uterine horn
‘Foal movement’ colics in mare - Signs? Diagnosis?
Mild-moderate medical colics
Common
Should respond to mild/moderate analgesia (buscopan or phenylbutazone)
Ischaemia/necrosis/rupture of caecum and colon colics in mare?
Syndrome of ischaemic necrosis of colon/caecum, potentially ending in rupture
Due to weight of foal applying pressure to viscera or stretching visceral blood vessels
Difficult to diagnose definitely - look for signs of peritonitis/endotoxaemia
Difficult to manage - lesions may be inaccessible at exploratory laparotomy
Uterine torsion colics in mares (pre-parturient): How common? When? Signs? Diagnosis? Treatment? Prognosis?
Rare Usually last third of pregnancy Usually low grade chronic or intermittent colic, but can be severe Diagnosis: - rectal palpation - one tight broad ligament - vaginal exam not helpful (twist cranial to cervix) Treatment: - surgery - standing flank laparotomy - GA and midline laparotomy - rolling under GA not recommended Prognosis after surgery: - 50% for live foal - 70% for live mare
Ventral oedema in pregnant mare?
Some mares develop large plaque of ventral oedema near term
May be due to compression of lymphatic drainage by foal
If mare well and oedema uniform and non painful then no treatment required - will resolve post foaling
Need to differentiate from other causes of abdominal enlargement
Pre-pubic tendon rupture in pregnant mares? Cause? Signs? Treatment?
Due to weight of foetus - more common in older mares
Large plaque of painful oedema, continuous with udder (‘dropped’ udder)
May be bloody discharge in milk
Often colic signs
Often spends more time recumbent
Treatment:
- analgesia (bute)
- will need assistance with foaling as cannot use abdominal pressure
- caesarean?
- will resolve if mare nursed through to foaling but often becomes more painful and results in euthanasia
- if survives do not breed from again
Hydrops amnion/hydrops allantois in pregnant mare? What is it? Signs? Diagnosis? Treatment?
Excessive fluid in allantoic/amniotic space
Up to 200L
May eventually cause colic, dyspnoea, recumbency, circulatory collapse
Foals usually deformed
Diagnosis: rectal exam (huge fluid filled uterus but foal out of reach)
Treatment:
- induce foaling or abortion
- dilate cervix, drain fluid off slowly
- manually remove foal
- IV fluids to maintain systemic BP
Placentitis in pregnant mares - Problems? Causes? Signs? Diagnosis? Treatment?
Eventually leads to abortion Ascending infection from cervix Strep, E.coli, Aspergillus Signs - premature udder development and lactation +/- vaginal discharge Diagnosis: - clinical signs - US demonstration of placental thickening - cervical swabs if discharging Treatment: - potentiated sulphonamides - bute
Varicose veins (varicosities) in mares - Problems? Treatment?
Most common cause of vaginal bleeding in mare - intermittent vulvar bleeding, blood pooling, worse at oestrus
More likely in pregnant or older mares
Usually no treatment required
Can do ligation/cautery/laser photocoagulation of vessels
Things needed for dystocia?
Sedation (and ketamine?) Clenbuterol or buscopan Local anaesthetic (epidural) Doxapram Foaling ropes Lubricant Hibiscrub Needles/syringes Waterproofs
Order of approach to dystocia?
Get things ready
Warn owner - guarded prognosis (may lose both)
Restrain mare (sedation? twitch? clenbuterol?)
Check mare not in shock/haemorrhaging
Clean perineum/arms
Vaginal exam - plenty of lube
Ascertain presentation/posture/position
Decide if vaginal delivery possible - if not refer for caesarean or euthanise
Check time if foaling possible and apply ropes/start traction
If no clear progress within 15 mins, re-assess, consider caesarean or controlled vaginal delivery under GA
Terminal caesarean = GA mare, cut foal out, euthanise mare
Embryotomy last resort - very damaging to mare unless operator very skilled
Uterine rupture/tear in pregnant mares - Problems? Diagnosis? Treatment?
Clinical signs evident 24-72h post foaling
If complete rupture, foal may fall into abdomen - no palpable in birth canal
Mare may fatally haemorrhage or will develop fulminating peritonitis and fatal endotoxaemia
Extract foal and consider euthanasia of mare
Smaller tears may only show as signs of peritonitis after foaling - better but still guarded prognosis
Diagnosis:
- clinical signs
- rectal/vaginal exam
- US
- peritoneal tap
Treatment:
- medical treat as for peritonitis
- exploratory laparotomy and repair for full thickness tears
Perineal lacerations during foaling - Significance/problems? Treatment?
Minor perineal lacerations are common during foaling
Many will heal without intervention
Lacerations which substantially disrupt perineal anatomy should be repaired, especially if natural healing will alter perineal conformation
This may be done immediately, or delayed for a few days if bruising is severe
Administer antibiotics/Nsaids/tetanus cover
Third degree perineal lacerations during foaling - How? Treatment?
Where foal’s foot has penetrated rectum and torn through anus
Rectum, vulva and vagina all communicate
Do not repair immediately - will break down
Administer antibiotics/Nsaids/tetanus cover
Repair required if mare to conceive again!
Delay surgery for 4-6 weeks until granulated in
Surgery difficult, several attempts often needed before complete repair occurs
Recto-vaginal fistulas – treat in same manner- delayed repair
Cervical lacerations in mare - Significance? Treatment?
May heal spontaneously or may need surgical repair
Repair probably best delayed until uterus involuted and inflammation subsided (one month post partum)
Therefore note and monitor – if cervical incompetence occurs mare will be sub -fertile
‘Uterine cramps’ causing post partum colic in mares - Signs? Treatment?
Many colics soon after foaling are put down to post-partum uterine contractions
Mild to moderate colics, no sign endotoxaemia
Should resolve with buscopan or phenylbutazone
What causes ischaemia/necrosis/rupture of caecum and colon causing postpartum colic of mares?
Expulsive forces of foaling
Inversion of uterine horn causing postpartum colic of mares - Cause? Signs? Diagnosis? Treatment?
After forceful foaling or too forceful removal of retained membranes
Colic which reoccurs despite analgesia
If mare continues to strain may proceed to uterine prolapse
Diagnosis by vaginal and rectal exam
Treat with analgesia, smooth muscle relaxants (buscopan/clenbuterol), manual replacement, uterine lavage
Colonic torsion causing post partum colic in mares? Cause? Treatment?
Post-partum mares prone to colonic torsion
Due to sudden increase of space in abdomen post foaling?
A surgical colic and rapidly fatal unless quickly corrected.
Rupture of uterine artery causing post partum colic in mares - What happens? Signs? Diagnosis? Treatment?
More common in older mares (atrophy of smooth muscle walls with fibrosis of arterial wall)
Haemorrhage may occur into broad ligament or into abdomen
Mild to moderate colic signs, which may progress to signs of haemorrhagic shock
May not respond well to Nsaids – painful?
May be contained within broad ligament, but if this ruptures or mare is haemorrhaging directly into abdomen then is likely to be rapidly fatal
Diagnosis:
- gentle palpation of broad ligament per rectum
- abdominal and rectal ultrasonography
Treatment:
- keep quiet – sedate?
- analgesia
- IV fluids – judiciously
- blood transfusions
- clotting agents – amino caprionic acid?, 10ml 10% formalin in 1 litre saline?
Uterine prolapse post partum in mares? Cause? Problems? Treatment?
Uncommon
After excessive traction on foal or RFM
After difficult foaling or if mare exhausted
May rupture uterine vessels and cause fatal internal haemorrhage
Even after replacement, death from metritis and endotoxaemia not uncommon
Treatment:
- clean uterus
- replace under epidural anaesthesia (standing sedation/GA)
- give oxytocin once replaced
- broad spectrum antibiotics and NSAIDs for anti-endotoxic effects
(rectal prolapses have similar aetiology and treatment – prognosis also poor as irreparable damage to blood supply of rectum usually has occurred)
Retained foetal membranes in mares - When normally passed? When to intervene? Problems if left?
2-10% of all foalings
Normal = within 2h post foaling
>4 hours is abnormal
When to intervene is controversial - most stud vets would advise treatment if still retained 4-6 hours post foaling
If left they decompose rapidly -> metritis -> endotoxaemia -> severe laminitis and death
Not all mares succumb to endotoxaemia - some tolerate RFM very well, others become very sick very quickly
Heavy horses traditionally considered very susceptible to effects of RFM
Each case must be taken seriously and treated promptly
Treatment for RFM in mares?
Oxytocin, antibiotics, flunixin (anti-endotoxic effects)
Check tetanus cover
Oxytocin alone may be enough to quickly stimulate passage
Poss manual removal (some think causes endometrial damage):
- gentle traction on allantois
- if doesn’t work, continued twisting of allantois is usually successful
- check placenta for retained fragments (tip of non pregnant horn most likely)
- if looks complete, 3-5d antibiotics and NSAIDs, rectal exam only if necessary
- if retained fragment cannot be located and removed, uterus lavaged until fluid is running fairly clear
- administer more oxytocin after lavage and turn out to exercise (aids involution)
- re-exam for further lavage in 12-24h
- maintain on antibiotics/NSAIDs
- keep lavaging until uterus involuting and little uterine fluid being generated
Metritis post partum in mares - Causes? Problem? Treatment?
May be due to unnoticed partial retention of placenta or due to contamination of uterus during foaling
May cause fatal endotoxaemia +/- laminitis if untreated
Treatment: antibiotics, NSAIDs, oxytocin and lavage (same as for RFM)
Signs of peri-parturient hypocalcaemua in mares?
Uncommon Muscle fasciculations recumbency Tetany Diaphragmatic flutter 'thumps'
Ideal external genitalia conformation of mares?
Labia vertically orientated
2/3 vulvar opening below floor of pelvis
Upwards orientation of vestibular opening - contamination if horizontal
What conformation problems can mares have which contribute to reproductive performance? How can they be helped surgically?
Pneumovagina - Caslicks, perineal reconstructions (Gadds)
Urovagina - urethral extension
Cervical incompetency - cervical repair
Delayed uterine clearance - uterine suspension
Oviduct blockage - oviduct lavage, prostaglandin
When is the Caslick’s procedure done? Method?
To improved vulvar competence - pneumovagina
Stocks/against doorway
Tail bandaged and held out of way
Wash perineum
Local anaesthesia
Excise thin band of mucosa from each side (3-4mm) from dorsal commissure
Do not oversuture in older mares - urovagina
Suture with non-absorbable material
Remove sutures 10-14 days later
Must open up close to foaling or will tear
When is the Gadds procedure performed?
= perineal reconstruction
Older mares - loss of perineal body, straight vestibule
Second degree perineal lacerations
When is urovagina seen in mares? Diagnosis? Surgical management?
Usually old, pleuriparous mares Often with pneumovagina Confirm diagnosis by cytology Rule out ectopic ureter in young fillies Improve BCS if thin Surgical management: - caudal relocation of transverse fold - urethral extension - urethral suspension?
What cervical injuries can mares get during parturition? When to treat?
Lacerations - surgery during diestrus >3 weeks post partum, stay sutures for traction, 3 layer closure
Adhesions
Incompetence
What surgery can help post mating persistent endometritis?
Uterine suspension:
- Restoration of normal horizontal orientation of uterine horns
- Improves uterine clearance
- Improves perineal conformation
- May reduce urine pooling
When do perineal lacerations usually occur in mares? Degrees? Treatment?
Usually during unassisted foaling of primiparous mares
First degree lacerations = mucosal damage - Caslick or no surgery required
Second degree lacerations = mucosa, submucosa and perineal muscles - Caslick and reconstruction of perineal body
Third degree lacerations = complete disruption of rectovestibular shelf, perineal body and anus - requires surgical repair, delay repair for 4-6 weeks
What causes a rectovestibular fistula during foaling?
Penetration of foal’s foot into rectum without progression to 3rd degree perineal laceration
Grnaulosa Cell Tumours (GCT) - Characterstics? Clinical signs? Diagnosis? Treatment?
Most common neoplastic disorder of mares' ovaries Unilateral Rarely metastasise Good prognosis Behavioural signs: - an oestrus/continuous oestrus - stallion like behaviour/aggression Diagnosis: - rectal exam: enlarged ovary - US: distinct honeycomb like appearance - endocrinology: increased testosterone in 50%, increased inhibit in 85%, increased Anti-Mullerian Hormone in 98% Treatment: - ovariectomy by laparoscopy (standing or under GA) or laparotomy under GA
What does it mean if an owner rings and says mare has ‘red bag delivery’?
Placenta has prematurely detached from uterus
= dystocia - emergency
Provide advice over phone
Options for dystocia?
Assisted vaginal delivery - conscious, use traction +/- ropes, sedation and epidural if mare straining excessively
Controlled vaginal delivery - mare anaesthetised +/- hindlimb elevated, delivered per vaginum
Caesarian section
Embryotomy
What is the gubernaculum?
Cranial - proper ligament of the testis
Middle - ligament of the tail of the epididymis
Caudal - scrotal ligament
Standing castration in horses - Drugs needed? Prep/aftercare?
Sedation - a2 agonist and opiate Bandage tail NSAIDs and antibiotics Aseptic preparation of scrotum Infiltration of local anaesthesia Repeat scrub Check tetanus status Box rest for 24h followed by controlled exercise Keep away from mares
Position of horse for field anaesthesia for castration?
Lateral recumbency
Elevation of upper hindlimb
Castrate lower testicle first
What to do when castrating a horse with a large cord?
Emasculate vascular and fibromuscular portions separately
What to do when castrating horse if history of scrotal/inguinal hernia?
Ligature around vaginal tunic +/- suture superficial inguinal ring
What to advice owners following horse castration?
Contact practice if:
- dripping from the incisions persists >4h or if there is a steady stream of haemorrhage
- evidence of tissue hanging from the incision
- marked swelling of the scrotum/stiffness that persists >3d
- depression, inappetent or colic
Complications following castration of a horse?
Swelling Haemorrhage Evisceration Omental prolapse Septic funiculitis Clostridial infection Septic peritonitis Penile damage Hydrocele Continued masculine behaviour Incomplete cryptorchid castration
Cryptorchidism - diagnosis?
Diagnosis:
- history: behaviour, previous surgery etc
- thorough external palpation: sedation, any testicular structures palpable and on which side?
- hormone analysis: hCG stimulation test for horses <2yo and donkeys of any age, oestrogen sulphate assay >/=3yo, anti-mullerian hormone (AMH)
- US
Diagnosis and treatment of inguinal herniation?
Diagnosis - palpation and US
Foals - conservative management or surgery if increasing in size or strangulating
Should be considered in all stallions/colts presenting with colic
Surgery - free entrapped SI, castration
Treatment of penile SCC? Prognosis?
Local excision
Cryotherapy
Topical chemotherapeutic agents
Surgery
- distal phallectomy (penile amputation): Vinsot’s, William’s or Scott’s technique
- segmental posthetomy (‘reefing procedure’)
- en bloc resection
Euthanasia - suspected metastatic spread
Prognosis good if treated early and appropriately
Define Priapism, paraphimosis and phimosis?
Priapism = persistent erection without sexual excitement
Paraphimosis = inability to retract penis into the
prepuce
Phimosis = inability to protrude the penis
Causes of pyospermia, haemospermia and urospermia?
External infection Cystitis Epididymitis Seminal vesiculitis Haemospermia - also external injury of skin/urethral process/injury Urospermia - also neurological function
How much should a foal grow per day?
0.5-1kg/day
What type of breeders are horses? What are the transitional periods?
Long day seasonal polyoestrus breeders
Most mares in an oestrus over winter
Increasing day length brings about breeding season from spring to late summer
Transitional periods:
- periods of irregular cycling at the start and end of the season
- lasts up to 6 weeks
- ovaries possess multiple small follicles 10-25mm in diameter
- transitional follicles fo not ovulate and eventually regress
- mares may show no signs of oestrus, erratic oestrus behaviour or constant oestrus behaviour
- will not conceive if mated
- eventually one follicle will develop properly and proper oestrus will commence
Mare oestrus cycle: How long is the cycle? How long is dioestrus? How long is oestrus? How long is she receptive to the stallion?
Oestrus cycle lasts about 21 days
Oestrus: 4-6 days (tends to be longer and weaker in early breeding season and shorter and stronger later on)
Dioestrus: 16-17 days
Oestrus ends within 24h of ovulation (no longer receptive after this)
Activity of follicles during the oestrus cycle in mares? Hormones produced? How big when ovulates? What does the ovulation site become? Action of CL? What causes luteolysis?
Waves of follicles develop during dioestrus and reach 25mm in size but then regress
When hormone conditions correct, one follicle is recruited and develops into a dominant follicle and ovulates
Dominant follicle produces oestrogen which induce oestrus
Ovulation when reaches >35mm
After ovulation, ovulation site becomes a corpus harmorrhagicum and hen a corpus lute which produces progesterone
CL is refractory to prostaglandins for 3-4 days
After about 15 days he endometrium releases prostaglandin which causes luteolysis and oestrus will begin again
How can prostaglandins, progestogens, oestrogens, chorionic gonadotrophin and deslorelin be used to manipulate oestrus?
Prostaglandins:
- induce luteolysis in receptive CL
- oestrus will commence 3-5 days post injection
- side effects: transient colic, sweating, diarrhoea etc
Progestogens:
- given orally to suppress oestrus
- withdrawal of treatment leads to rebound of ovarian activity (useful to shorten length of spring transitional period)
- intra-vaginal devices (PRID) sometimes used off licence
- sometimes used to maintain high risk pregnancies
Oestrogens:
- induce behavioural signs of oestrus but not true oestrus
- only useful for maintaining ‘teaser mares’ for AI collection
Chorionic gonadotrophin:
- if given during oestrus will induce the dominant follicle (>35mm) to ovulate within 24h
Delorelin:
- = GnRH analogue
- hormone implant given subcutaneously when follicle >30mm
- should induce ovulation within 48h in most mares
How can the photoperiod be used to manipulate oestrus in mares? Why done?
Breeding season can be brought forward by use of artificial light over winter
Many protocols but providing 16 hours of light and 8 hours dark from 2-4 weeks before Winter solstice commonly used
Light intensity important (should be able to read a newspaper in darkest part of stable)
Mares start to ovulate 8-10 weeks later
Only really of use for Thoroughbreds destined for Flat racing:
- Thoroughbreds registered with Weatherbys have their official birthday on Jan 1st
Flat race horses often start racing as 2 year olds so there is a size advantage in being born as early as possible
- In the UK the thoroughbred breeding season starts on Feb 15 and ends on July 14
Why is oestrus suppression not always straightforward when asked for by owners to control difficult sexual behaviour? What should you do before trying?
Behaviour problem may actually be non-sexual in nature (poor training, orthopaedic pain etc)
Behaviour may be sexual but not hormone related (eg social “flirting” even if out of oestrus)
Some mare sex hormones also produced by brain and adrenals
Treatment may damage potential future breeding career
Discuss limitations carefully with owner to prevent disappointment:
- Scan ovaries/uterus
- Check for Granulosa cell tumour (blood sample)
- Keep diary of problems (is it cyclical?)
- Rule out other causes of bad behaviour if possible
Methods of oestrus suppression in mares?
- Long term Progestagens:
- Expensive
- Sedative effect in own right
- May be allowed under FEI rules with special dispensation
- Won’t affect adrenal/brain hormone production
- Long acting i/m progestogen injections? - Intra-uterine devices (Marbles “Mare-bles”)
- Supposed to replicate pregnancy and suppress oestrus
- Shown to have little effect on hormonal cycling (some pregnancies reported in treated mares!)
- Increasing evidence of harmful complications
- Popular with clients (placebo effect mostly)
- Not to be encouraged - Anti-GNRH vaccination
- Licensed in Australia “Equity “
- Not available in UK but pig vaccine “Improvac” has been used off license
- Some severe swelling/abscessation at injection sites reported
- Permanent infertility possible - Induce long term Corpus luetum (repeated oxytocin injections after oestrus)
- Plant oils infused into uterus
- Put in foal (terminate foal at 6 weeks?)
- Ovariectomy
- Invasive
- Expensive
- May not work if not hormonally mediated
- May induce permanent oestrus via adrenal hormone etc
- Induces infertility
- Counsel client carefully before recommending (last resort)
Timing of mating in mares?
Oestrus behaviour ceases within 24 hours of ovulation (mare no longer receptive to stallion)
Unfertilised oocyte viable for only 12 hours post ovulation
Matings after ovulation have very poor conception rates
Spermatozoa reach oviduct within hours of insemination
Spermatozoa viable for up to 48 hours once in the mares reproductive tract
Therefore serve mares 24-48 hours prior to ovulation
How will a mare in oestrus look, feel on rectal and appear on US? What to do if is/isn’t in season on US? How to know when close to ovulation?
- Dominant follicle on one ovary
- Uterine oedema
- Soft oedematous cervix
- Behavioural signs
If in oestrus and follicle >35mm and uterine oedema maximal or regressing then mate!
If in oestrus but follicle <35mm and uterine oedema not maximal or regressing, scan again 24-48h later
If not in oestrus, give PG and scan again 3-5d later when starts to come into oestrus
Use hCG if required to force ovulation and serve straight after
Close to ovulation when dominant follicle starts softening and ‘pointing’
Endometrium becomes increasingly oedematous during oestrus:
- cartwheel oedema
- then decreases in the 24h before ovulation
Post mating scanning: when and why? When to re-scan?
24-48h after mating to:
- see if ovulated (if not, mate again?)
- check only one ovulation (twins)
- check for fluid in uterine lumen (treat accordingly if post mating endometritis)
Re-scan in 24h if uterine fluid to check resolved
Re-scan in 15-16 days if clean for pregnant exam
What 3 mechanisms prevent bacterial entry to the uterus? Why may these not be present? Problems if not?
- Vulval seal
- Vestibular seal
- Cervical competence
Not present if poor perineal conformation
Failure of vulval and vestibular seal allows pneumovagina (predisposes to urovagina) which leads to cervicitis and bacterial contamination of the uterus
Uterine contamination -> endometritis -> failure of implantation of conceptus
What is good perineal conformation?
No more than 4cm of vulva above the pelvic brim
No greater than 10 degree slope to the vulva
Anovulatory follicles: Problems? Treatment?
Cause prolonged oestrus Follicle increases in size to 10cm but never ovulates May then be a prolonged luteal phase Usually regress in 4-6 weeks May respond to prostaglanding
Persistent CL: Problems? Treatment?
No oestrus
Give prostaglandins
Why is endometritis a problem when trying to get a mare pregnant?
Doesn’t affect conception but will affect implantation and inflammatory prostaglandins released may hasten luteolysis
What are the 3 types of endometritis in mares? Features of each?
- Chronic infectious metritis:
- often caused by contamination of reproduction tract due to poor perineal conformation
- Strep zooepidemicus, E.coli, Pseudomonas, Klebsiella
- CEM - Free fluid in lumen:
- as a result of uterine oedema during oestrus
- may be sterile initially but good culture medium for bacteria
- delated uterine clearance by incompetent mares - underlying motility disorder? - Mating induced endometritis:
- mating contaminates repro tract with flora on stallion’s penis
- semen is inflammatory
- transient inflammation normal
- should clear up within 12h
- persists in some mares (abnormal uterine defences) and leads to embryonic loss and possibly chronic endometritis
Investigation of endometritis?
Scan (especially post service) - persistent fluid or fluid >1-2cm in depth needs treating
Uterine swab and smear for culture and cytology
Endometrial biopsy for histopathology very useful
Treatment of endometritis?
Can treat in first 5 days without jeopardising pregnancy as conceptus still in oviducts
- Uterine lavage (saline)
- Oxytocin (every few hours)
- Intrauterine antibiotics e.g. ceftiofur
- AI to minimise contamination
Chronic degenerative endometrial disease (endometriosis): What happens? Cause? When? Diagnosis? Treatment?
A progressive degeneration of endometrium and its replacement by fibrotic tissue
A major cause of age related infertility in mares (esp. TBs)
Begins about 11-12yo
By 17yo may have progressed to severe stage
Pregnancy seems to have protective effect, lessening progression of condition
Diagnosis:
- Histopathology on endometrial biopsy (can be used to compare against “normals” for the age of the mare)
Treatment:
- None?
- Mechanical curettage?
- Thermal curettage (hot saline)
Cervical incompetence: causes? Problem? Treatment?
Either from congenital problems or as result of foaling injury
Often overlooked but important potential cause of infertility
Surgical repair/improvement sometimes possible –always difficult!
Uterine cysts: Problems?
Rarely a cause of infertility unless very large
Can cause problems at pregnancy diagnosis (look similar to a pregnancy) but unlike pregnancies they remain static in size and shape - re-exam the mare in 24-48 hours
What pre-breeding disease checking is carried out?
Varies from stud to stud
Often a clitoral swab for CEM:
- Sample clitoral fossa and sinus
- Use an in date mini tip swab and place in Charcoal Amies medium
- Send to approved lab - must arrive within 48 hours
- Results take 7-10 days
- Also tested for Klebsiella and Pseudomonas.
Blood sample for Equine Viral Arteritis also often asked for - serology
Strangles serology also being asked for by an increasing number of studs
How long is equine pregnancy?
Average is 340 days
Very variable
‘Overdue’ foals rarely cause a problem
Timeline of equine pregnancy?
Fertilisation in ampulla of oviduct
Embryo remains in oviduct until day 5-6 when it enters the uterus
Embryo migrates around uterus up to day 15-16 (essential for maternal recognition of pregnant and prevention of release of PG by endometrium)
Fixes in position on day 15-16 (usually at base of one horn)
Placental attachment begins at 36 days
Production and attachment of endometrial cups occurs at about the same time
Foetus grows into uterine body after 70-80 days
Found mostly in body until 6-7 months, after which it is so large it occupies part of the horn again
Endocrinologogy of equine pregnancy?
First 14 days similar to dioestrus
Maternal recognition of pregnancy prevents regression of primary Cl from 14 days onwards
CL produces progesterone to maintain pregnancy
Endometrial cups start secreting eCG from day 35 to maintain primary CL and encourages secondary CL formation
CLs and cups maintain pregnancy for first 5 months
Cups start to degenerate after about day 70 so eCG levels start to fall, followed by progesterone levels
Cups gone by day 150
After about day 200 all CLs have degenerated
Pregnancy now maintained by foetal-placental progesterone production which acts locally
Foetal gonads produce oestrogens from day 60 onwards
Why must any attempt to abort a foal be done before day 35 if it is desired to get the mare to breed again in the same breeding season?
Once in place and producing eCG, the endometrial cups can only be removed by natural regression (regression occurs between day 100-150)
Whilst they are in place the mare will not come into oestrus
Cups remain even if foal has died
Methods of pregnant diagnosis in mares? Considerations?
Failure to return to oestrus:
- but may be other reason
- some mares show signs of oestrus during pregnancy
Lab tests:
- eCG (blood) from days 45-90
- oestrone sulphate from day 120 onwards (blood) or day 150 onwards (urine) - indicates foetal viability
Manual rectal exam:
- possible at day 20 if very skilled
- usually left until day 40 (6 weeks)
- may be able to ballot foetus by day 120
- mostly replaced by scanning
Rectal US:
- possible from day 10
- but embryonic death rates highest in first 14 days
- if twins, one twin can be days younger (smaller) than the other
- conceptus motile until day 16 (useful to distinguish cyst from twin and twin from twin
- twins reduction better done when smaller
- after day 35, endometrial cups will prevent mare returning to oestrus if pregnancy is terminated
- after 6 weeks can’t image whole foetus
- can also do trans abdominal US from 6 weeks onwards
Common routine for US pregnancy diagnosis on a professional stud?
First scan 15-16 days post mating:
- check for pregnancy or impending return to oestrus
- check for twins (reduce while motile and can be separated)
Second scan 24-26 days:
- heartbeat visible (chance of embryonic death lower)
- still can reduce twins (more difficult)
- before cups established so still option to terminate pregnancy
Third scan 6 weeks (optional):
- reassess (embryonic death unlikely now
VDS advice for PD and twins?
Scanning twice, first at 14-18 days after last mating and again at 28-35 days after last mating will reduce the risk of missing twin conceptions but will not eliminate it altogether
If pregnancy diagnosis must be restricted to a single exam, then it is best performed between 28-35 days after last mating
If owners understand the limitations of scanning for pregnancy in mares, it is less likely that their expectations of this procedure will be disappointed
When are failed pregnancies called early embryonic death, abortion or stillbirth? Causes of failure?
Early embryonic death = fertilisation to day 40
Abortion = day 40-300
Stillbirth = day 300 onwards
Causes:
- early embryonic death
- viral: EHV, EVA
- bacterial
- fungal
- twins
- maternal illness/stress (esp if endotoxaemia or pyrexia)
- foetal abnormalities
- umbilical torsion
- idiopathic
- others
Causes of early embryonic death in mares? Diagnosis?
Congenital/genetic abnormalities
Breeding on foal heat
Uterine environmental problems - fibrosis, endometritis
Diagnosis - empty on repeat scan, abnormal size or shape of conceptus
EHV1 abortion - How common? When? Other signs? Spread? Diagnosis? Treatment? Prevention?
Most common cause of infectious abortion
Ubiquitous virus
Abortion usually late term (>5 months), 1-3 months post infection
Often no warning signs
Foals may be born alive but very weak (these quickly die)
Spread mainly by respiratory route but aborted foetus, membranes and vaginal discharges highly contagious
Diagnosis:
- nasopharyngeal swabs for horses showing respiratory signs (PCR)
- submission of aborted material (PCR)
Treatment:
- none for individual cases
- isolate and disinfect
- separate pregnant mares from young stock
Prevention:
- vaccination in 5, 7and 9 months of pregnancy may reduce risk of disease but does not give full immunity
Equine viral arteritis abortion: When notifiable? Spread? Prevention?
Notifiable in UK in Stallions and mares mated in last 14 days
Infected stallions become persistently infected shedders
Infected mares abort then recover
Vaccine available - make sure animal tests seronegative for EVA before vaccination
Naturally seropositive animals in UK population
Clinical disease rarely seen in UK but has occurred
Bacterial abortion in mares: Which bacteria? Cause? Treatment?
Often Strep spp Also E.coli and Staph spp Occasionally Salmonella, Leptospirosis Cause: - Ascending infection from cervix - Haematogenous spread - Introduction of bacteria at breeding Treatment: Antibiotics/Nsaids but often too late
Fungal abortion: How common? Which fungi?
Rare
Usually Aspergillus
Twins: Why not desirable? How common? Difference between unilateral and bilateral horn twins?
25% of TB ovulations are twins (2 separate eggs released)
Mare not designed to carry more than one foal:
- placenta needs to contact up to 70% of available uterus for adequate nutrition of foetus
- often one twin will run out of space early on and die, then the other grows until it is deprived of space by the remnants of the dead twin and aborts
- twins in one horn (unilateral) are more likely to end up with one surviving to term as one twin may die early on whilst very small
- twins in opposite horse (bilateral) are more likely to abort as both will get to reasonable size before they begin to compete
- 60% single live foal, 30% both foals lost, 10% both live but 6% of these both stillborn
- overall 63% chance of a live foal
Occasionally both foals survive to term but in most cases both foals are lost
Reduction of a twin?
Rectum must be related so may use sedatives and hyoscine
NSAID often used to prevent induced inflammation affecting the other foetus
Mare scanned again in 24-48h to ensure reduction was successful
Clinical signs of abortion?
May be none - mare found to be empty Mare often fine in self If mare off colour, may be the cause of the abortion, not due to the abortion Vaginal discharge Running milk Colic/foaling signs
Investigation of an abortion?
Send whole carcass and placenta to pathologist if possible
Examine placenta and cord
External exam of foal -weight, crown-rump length
Internal exam - signs obvious problems
Sample chorion, thymus, liver, lung, spleen, fresh and fixed (can be tested for EHV plus bacterial culture, and histopathology)
Samples from mare rarely useful
Assume contagious until results back!
How to induce abortion in mares?
Before 3 months:
- prostaglandin injection for abortion 5-8 days later
After 3 months:
- repeated prostaglandin injections (e.g. twice daily to cause abortion in 2-5 days if between 80-150 days)
- 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 to terminate pregnancies after 100 days
How to induce foaling? When? Why? Risks?
Oxytocin every 15-20 mins until delivery starts (may only need one dose) But risky procedure, needs mare to be basically about to foal anyway - avoid unless absolutely necessary Carefully assess mare: - udder development - milk electrolyte levels - vulval and sacrosciatic relaxation Risks: - uterine rupture - dystocia - foal immaturity (matures in last 1% of pregnancy) - retained membranes Warn owner of risks!!
Risk factors for neonatal illness?
Mare: - placentitis - placental insufficiency - maternal illness - early lactation - poor colostral protection Foal: - prematurity - FPT - other illnesses Gestation and parturition: - prematurity - dystocia - placental separation
How long does it take for foal adaptation to external environment? What needs to adapt? What are prematurity and dysmaturity?
24-48h
- cardiopulmonary
- GIT
- urinary
- thermoregulation
- endocrine
- neurological
- skeletal
Prematurity = foal born at a gestational age of <320 days that displays immature physical characteristics Dysmaturity = a full term foal that displays immature physical characteristics
Physical characteristics of prematurity/dysmaturity?
Low birth weight Short silky hair Floppy ears Domed head Weakness, prolonged time to stand Flexor tendon laxity Incomplete ossification of carpal and tarsal bones
What is the problem with premature/dysmature foals in severe cases?
Multiple organ dysfunction in severe cases:
- GI
- neurological
- renal
- endocrine
What is the immune function of a foal when born? Colostrum importance?
Immunocompetent at birth But immunologically naive Autogenous IgG adult levels by 4mo Gap in protection when maternal IgG falling (decline by 1-2mo) and autogenous IgG rising Gap filled by colostrum: - IgG, IgG(T), (IgA, IgM) - complement, cytokines, lactoferrin
Absorption of colostrum? How much colostrum needed?
Specialist enterocytes absorb Igs by pinocytosis
These cells have a lifespan of a maximum of 24h
Maximum absorption within 8h of life
Foal must ingest around 1L of colostrum within first 6h
Normal levels of IgG in a foal and FPT and PFPT? How to test?
Normal transfer >8g/L
PFPT 4-8g/L
FPT <4g/L
IgG not detectable <6h (peaks at 18h - best time to test)
Testing:
- RID
- ELISA (SNAP foal IgG test)
- ZnSO4 turbidity
- Glutaraldehyde coagulation
- TSP/globulins
- SG of colostrum pre-suck (modified refractometer, colostrometer)
Normal timings for suckle reflex, standing and sucking of newborn foals?
Suckle reflex: within 20 mins
Time to stand: 1h
Time to suck: 2h
Predisposing factors for FPT in foals?
Loss of colostrum via premature lactation: - twins - placentitis - premature placental separation Inadequate colostrum production: - severe illness - premature foaling (colostrum produced in last 2-4 weeks) - endophyte infected fescue Failure to ingest adequate volume: - neonatal weakness - rejection of foal Failure to absorb colostrum: - premature - concurrent illness - endogenous or exogenous glucocorticoids may hasten maturation of specialised enterocytes
Treatment for FPT in foals?
Give colostrum if delay in suck
Risk of septicaemia so always treat sick foals
Plasma if >12-24h
Colostrum if <12h
Consequences of FPT in foals? Risk factors?
Immediate: Septicaemia At 1-4mo: - Rotavirus - Respiratory disease - Joint sepsis
Risk depends on:
- stress
- management
- hygiene
Normal body temperature, HR and RR of newborn foals?
HR: 40-80 at birth, 60-100 in first week
RR: 45-60 at birth (small abdominal component, no nostril flaring or exaggerated rib movement, periods of tachypnoea during REM), 35-50 at 1 week
Temperature: 37.2 - 38.9 (reflects environmental temperature)
When should urine and meconium be passed by newborn foals?
Urine: dilute large volumes first passed by 6h (colts) or 10h (fillies)
Meconium: dark brown pellets or paste all passed within 24h
Average weight of newborn foal? Weight gain/day? Daily consumption of mare’s milk?
Average weight: 45-55kg
Weight gain: 0.5-1.5kg/day
Daily consumption of mare’s milk: 20-28% BW
Normal auscultation of foal lungs?
Harsh bronchovesicular sounds
Crackles present in ventral dependent side if in lateral recumbency
Interpretation of foal mucous membrane colour?
Cyanosis = PaO2 <30-40mmHg
Signs of sepsis: congestion/injection, petechiae
Prognostic factors for an unwell newborn foal?
More likely to survive if mare problems chronic rather than acute
Owner/vet recognised problems and acted quickly
Transportation to appropriate hospital with good supportive care before and during transport
Response by 24h into treatment is often good indicator
Identification of sepsis in foals?
Blood culture:
- delay before results available
- prior antibiotics reduces likelihood of positive culture
Sepsis score:
- developed to overcome limitations of blood culture
- I CBC: neutrophil numbers and morphology
- II Other lab data: fibrinogen, blood glucose, IgG
- III Clinical exam findings
- IV Historical data
US for umbilical infection (compare size of umbilical vessels to each other and normal values)
Radiography and blood gas analysis for pneumonia
Radiography and synovial fluid analysis for osteomyelitis/arthritis
Intensive medical therapy/nursing used for a sick neonate?
Fluids +/- glucose, electrolytes
Antibiotics
Immunoglobulin (plasma or hyperimmune serum)
NSAIDs (flunixin for septicaemia/SIRS foals)
Anti-ulcer medications (sucralfate or omeprazole)
Circulatory support: dobutamine, dopamine
Diuretics if persistent oliguria: furosemide or mannitol Nutrition: 20% BW milk/day (10L minimum split into 2 hourly feeds) Warmth Management of recumbency Respiratory support: - postural (sternal recumbency best!!) - intranasal O2 - mechanical ventilation - drugs: bronchodilators, caffeine
Monitoring of a sick neonate?
Repeat clinical exams frequently Fluids ins and outs (esp urine output) Lab results: electrolytes, foal profiles, USG Radiography US BP Arterial blood gases Cardiac output
Antibiotic selection for a sick neonate (septicaemia/SIRS/sepsis)?
Aminoglycosides: - care in v young foals (nephrotoxic) - used in conjunction with G+ve cover Penicillins Ceftiofur (high frequent doses) Cefquinome
Differentials for a neonate with respiratory signs?
Neonatal septicaemia - first, most important ddx of any sick neonate (-> bacterial pneumonia) Viral pneumonia Meconium aspiration Aspiration pneumonia Haemothorax and pneumothorax Respiratory distress syndrome Pulmonary hypertension Central respiratory depression
Neonatal septicaemia risk factors?
FPT major risk factor Hygiene Stress Management Disease Virulence of pathogens
What are common pathogens causing neonatal septicaemia?
E.coli Actinobacillus Salmonella Proteus Klebsiella B haemolytic Strep Staph Clostridia
Routes of entry for neonatal septicaemia?
Umbilicus
Open gut
Inhalation
In utero
Clinical signs of neonatal septicaemia?
Foal goes off-suck and is lethargic Increased respiratory rate and effort Acute severe lameness Discharge or swelling of umbilicus Fever is not consistent Congested, dark mucous membranes or severe cases petechial haemorrhages Hypopyon Diarrhoea (often only once fluid Tx started) Meningitis
What happens when neonates go into septic shock?
Vasoactive inflammatory mediators lead to vasodilation
Increased metabolic rate and oxygen consumption
Cardiac output is increased initially (hyperdynamic
phase)
Microvascular permeability leads to volume maldistribution
Increased cardiac output can no longer be maintained (hypodynamic phase)
Culminates in:
- Multiple organ failure
- CNS depression
- Renal failure
- Autonomic exhaustion and decompensation fo circulation
Treatment and prognosis of neonatal septicaemia?
Early recognition, intervention and management essential
Transportation to hospital essential for good medical and nursing support
Always guarded prognosis
Long term complications e.g. joint infections
What is SCID? Cause? Signs? Diagnosis?
Failure to produce functional B and T lymphocytes Autosomal recessive in Arabians Normal at birth Disease begins at 1-2mo Especially respiratory infections - Pneumocystis carinii, adenovirus pneumoni Lethal Diagnosis: - signs - persistent lympopenia (<1x10^9/L) - WBC count may be normal - confirm at PM (hypoplasia of LNs, thymus and spleen) - genetic testing
What is perinatal asphyxia syndrome (PAS)? What happens? Cause? When? Signs? Signs with different severities?
Dummy foals, HIE Ischaemia, oedema and repercussion injury to brain, kidneys, intestine etc due to lack of O2: - in utero hypoxia - interruption of O2 supply during birth May not be apparent until 12-24 hours old Predominant sign in >90% of cases is hypoxic encephalopathy Severe cases may have central respiratory depression Mild: - unable to attach to mare - poor suckle reflex Moderate: - aimless wandering - abnormal phonation (barkers) - blind Severe: - seizures - coma
Treatment and prognosis of PAS?
Prognosis good if sepsis score <11 (not septic) with good nursing:
- can take up to 2 weeks
- expensive
Antibiotics, nutrition, care of eyes, stop damage to self etc
Mannitol if cerebral oedema
Compression squeeze
Control of seizures: diazepam, phenobarbital
What is different about foal urine?
Newborn foals have proteinuria - colostral absorption of small molecular weight proteins (first 1-2 days)
Develop hyposthenuria after about 2 days of life (remains so for many months)
What is different about foal plasma urea and creatinine?
Creatinine of newborn foal is normally 30-40% higher than an adultUrea very low in foals after about 2do for several months
Differential diagnoses for neonate with colic?
Meconium impaction Ruptured bladder/uroperitoneum Overfeeding/lactose intolerance Distension associated with diarrhoea Gastric ulcers SI/LI obstruction Congenital abnormalities
Differentials for anaemia in the neonate?
Blood loss (also low protein): e.g. umbilical artery or post nasal haemorrhage from trauma/injury Haemolysis (normal protein): esp. neonatal isoerythrolysis
Neonatal isoerythrolysis: When happens? How common? Diagnosis? Prevention? Treatment?
Aa and Qa negative mares mated to positive stallions
Low incidence <1%
Haemolytic anaemia from 24h
Diagnosis:
- clinical signs
- confirm by detecting Ab on RBCs (coomb’s test)
- agglutination/haemolytic assays of colostrum
Prevention:
- avoid incompatible matings (blood type both parents)
- prevent Abs entering foal
- if mare known to be at risk, test sera for anti-RBC abs
- jaundiced foal agglutination (JFA) test (can monitor when safe to put mare back with foal, can be 4h if milked out)
Donor:
- Aa and Qa negative horse
- Washed mare red cells
- JFA test using mare’s colostrum and blood from potential donors
Treatment:
- blood transfusion if PCV <12-15%
- if PCV >15%, remove source until safe, limit movement and stress
- supportive care for sick foal (Abs, anti-ulcer meds, monitor fluids, glucose, nursing)
Differentials for jaundice and weakness of a neonate?
Neonatal isoerythrolysis Tyzzer's disease (necrotising hepatitis) EHV1 Sepsis Excess iron
Fell pony syndrome: What happens?
Fell and Dales breeds
Anaemia, weakness and rapid loss of condition from 2-3wo
Severe immunodeficiency
Severe secondary illness e.g. diarrhoea, pneumonia
Invariably fatal
Genetic test available
Differentials for neonatal diarrhoea?
Foal heat diarrhoea
Neonatal septicaemia (Gram negatives e.g. E.coli, Salmonella)
Clostridia
Campylobacter
Foal heat diarrhoea: Pathogenesis? Clinical signs? Treatment?
Pathogenesis unclear: - 5-12do (mare's first oestrus) - changes in bacterial flora - alteration in milk consumption relating to hormonal changes in milk Clinical signs: - mild, self limiting diarrhoea - generally bright and sucking Treatment: - nothing - intestinal protectants e.g. kaolin, bismuth subsalicylate - probiotics Good prognosis
Clostridial diarrhoea of foals: How bad? Which species? Diagnosis? Treatment?
Severe, parachute, frequently fatal Necrotising - foul smelling faeces Individual septicemia foals or outbreaks C difficile and perfringens most common Normal GI inhabitants Severe gas distension and colic Contagious - isolate! Diagnosis: - culture (normal flora so difficult to interpret) - ELISA or PCR for toxins - gas in or on the mucosa on US Treatment: - metronidazole - penicillin
Differentials for diarrhoea in older foals and weanlings?
Rota virus
Other viruses (coronavirus, adenovirus, parvovirus)
Stronglyoides westeri (not thought to be a major pathogen unless present in high burdens or accompanied by other agents)
Crytosporidium
Giardia
Rhodococcus equi
Cryptosporidium: When seen? Spread? Pathogenesis? Incubation? Diagnosis? Treatment? Prevention?
Previously thought to be important only in immunocompromised foals but now recognised as primary pathogen May accompany other agents No intermediate host Faeco-oral infection Attach to brush border Incubation 3 - 7 days Diagnosis: - faecal oocysts by sugar float or direct FA test Treatment: - supportive therapy - no specific coccidiostat shown to be effective Prevention: - good hygiene and management
Viral diarrhoea in foals: Which foals affected? Pathogenesis?
Rotavirus: all foals
Adenovirus and coronavirus: immunocompromised foals
Pathogenesis:
- Invade epithelial cells lining the intestinal villi
- Cell death and blunting of villi
- -> Maldigestion through loss of intestinal enzymes and malabsorption through loss of surface area
Rhodococcus equi diarrhoea in foals: How infected? Signs?
Excreted in dam’s faeces
Builds up on pasture in warm, dry conditions and ingested
Enteric infection - persistent diarrhoea, fever
Intra-abdominal abscesses - fever, coli
Less common than respiratory forms
Equine proliferative enteropathy (EPE): Aetiology? Signs? Age affected? Spread? Diagnosis? Treatment?
Lawsonia intracellularis Signs: - weight loss - oedema - lethargy - depression - weakness - (diarrhoea, mild colic, episodic pyrexia less common) 3-11mo usually Infection from faeces (other horses or other species inc wild animals) Diagnosis: - US - hypoproteinaemia - PCR of faeces - serology Treatment: - antibiotics e.g. erythromycin/rifampin - oxytetracylcine - should see rapid response
What is the cut off for the foal sepsis score?
Non septic: <11
Septic: 11 or more
Rotavirus diarrhoea: Age affected? Presentation? Diagnosis? Treatment? Prevention?
1-4wo Highly infectious - outbreaks Diagnosis: - electron microscopy - ELISA Treatment: - passive immunisation - supportive therapy Prevention: - vaccinate pregnant mares (local gut immunity) - vaccination - phenolic disinfectants (bleach not effective)
