Equine Flashcards
What can be used to treat head shaking if you are suspiscious it has a photic/trigeminal component?
Cyproheptadine or Carbamazepine.
What is the normal temperature of the horse?
38C+- 0.5
What does EHV 1 usually cause?
Abortion in last trimester.
What is the pathognomic lesion for EHV1 infection?
Histological inclusion bodies in foals liver, lungs and thymus.
What does neutrophilia over >5% seen in BAL suggest?
RAO, SPAOPD, IAD, pleuropneumonia, acute
At what age do foals usually develop signs of rhodococcus equi penumonia?
infected as neonates by inhalation or ingestion of environmental bacteria but do not develop clinical signs until 2-6 months old. Bacteria reside intraellularly, particularly in phagocytes, leading to multifocal pulmonary abscessation.
What is the treatment for rhodococcus equi?
Rifampin and erythromycin for several weeks.
What are your differentials for acute infectious respiratory disease in adults?
Influenza, EHV1 EHV4 Rhinovirus EVA Strangles. Mycoplasma felis, equirhinis, bordetella bronchiseptica, streptococcus pneumonia, pasteurella spp, actinobacilluus sp.
What does EHV1 cause?
occasionally respiratory disease, more commonly abortion and encephalomyelopathy.
What are the signs of equine viral arteritis?
Respiratory disease, severe conjunctivitis, profound depression, periorbital oedema due to vasculitis.
What is bastard strangles?
A complication whereby abscessation occurs in other tissues including mediastinal and mesenteric lymph nodes and physes. Affected horses present with fever, malaise, weight loss and signs related to local abscesation.
Which type of hypersensitivity reaction is Purpura haemorrhaghica?
Immune mediated (type 3) - occurs 1-3 months after strangles infection, signs include oedema, petechiation, pyrexia, tx with dexamethasone, penicillin.
When can you be sure a horse has recovered from strangles?
3 consecutive nasopharyngeal swabs negative at weekly intervals
How is dictyocaulus arnfieldi diagnosed?
Eosinophilia in tracheal mucous or by response to anthelmintics - infections in horses are usually non patent and consquently the baerman faecal flotation technique is unreliable.
What are the clinical signs of pulmonary oedema in horses?
Frothy nasal discharge, increased inspiratory effort, widespread fine crackles on auscultation.
You are examining a 3-day old neonatal foal for suspected sepsis. Upon review of a blood smear, you notice the blue aggregates in many of the neutrophils (see image). What are these called and what do they suggest?
Dohle bodies are bluish-gray inclusions within the neutrophil that are retained aggregates of rough endoplasmic reticulum. Dohle bodies are one manifestation of toxic (i.e. endotoxemia) morphologic change to the leukocytes.
Other changes in neutrophil morphology that occur with toxemia include cytoplasmic basophilia, vacuolation, and toxic granulation. These changes are commonly found in septic foals and may be considered “defects” in the neutrophil during intense cell production and maturation. In this image, there are numerous dark blue aggregates suggestive of Dohle bodies.
What breed of horse is predisposed to development of recurrent uveitis and equine night blindness?
The correct answer is Appaloosa. Equine night blindness is a congenital disease that is bilateral and nonprogressive, wherein horses have variable degrees of decreased vision in the dark. Recurrent uveitis is a very important condition in the horse and is actually the most common cause of blindness in the horse. Appaloosas are overrepresented, but the disease can occur in any breed. It is thought to be related to certain pathogens including Leptospira, Onchocerca, Toxoplasma, Brucella, and other infections, but these relationships are poorly characterized. Affected horses have recurrent bouts of inflammation, and each episode causes progressively worsening intraocular damage. The condition is sometimes referred to as moon blindness.
Which of these tests is most reliable in diagnosing a uterine infection in a mare?
the correct answer is uterine cytology. Endometrial cytology will show a more quantitative measure of not only bacteria but of leukocytes. Because there are many commensal organisms found in and around the uterus, culture is neither sensitive nor specific. However, it is often a worthwhile test to determine what organisms are there and to design an appropriate antibiotic plan based on susceptibility results. A cervical swab is less reliable than an endometrial sample. CBC is neither sensitive nor specific for diagnosing endometritis. The presence of a high percentage of neutrophils in an endometrial cytology is very suggestive of uterine infection, especially if bacteria are also seen.
Why might a thrill be felt in the cardiac area?
A diastolic thrill on the left hemithorax is most likely caused by aortic insufficiency, systolic thrill on left hemithorax by mitral regurgitation, systolic thrill on right hemithorax by tricuspid regurgitation or ventricular septal defect.
What is the most common cause of poor performance in thoroughbred racehorseS?
Atrial fibrillation
Which drugs may cause toxic damage to the myocardium in horses?
Salinomycin and monensin. Monensin causes acute myocardial necrosis leading to fibrosis.
What treatments are available for Atrial fibrillation?
quinidine sulphate - anti arrythmic drug. Sudden death may occur. toxicity incudes urticaria, diarrhoea, anorexia, weakness. Heart rate and rhythm must be monitored throughout treatment.
Conversion of AF to normal sius rythm only occurs in 87%, and sudden death is rare but does occur. if horses fail to revert to sinus rythm during initial regimen then quinidine administration should be continued at six hourly intervals following a period of 24 hours without drug administration. Digoxin should be given every 12 hours until sinus rhythmn is restored.
Does aortic insufficiency predispose to sudden death?
Aortic insufficiency causes decreased coronary perfusion due to reduced diastolic aortic pressure and oxygen delivery to the myocardium is compromised. increased oxygen demand and reduced coronary reserve increases susceptibility to ventricular arryhthmias that can result in sudden death.
What is the most common congenital abnormality in large animals?
Ventricular septal defect
Where are septal defects most commonly located in horses?
In the membranous septum below the aortic and tricupsid valves. Most common in the shetland and welsh mountain ponies.
What are the clinical signs of salmonellosis enterocolitis?
May be precedeed by colic
Diarrhoea usually occurs 24-48 hours following fever
Associated with signs of endotoxaemia and hypotensive shock
Reduced intestinal sounds followed by an increase in intestinal sounds. Transrectal palpation reveals fluid filled colon and caecum.
What are the clinical signs of cyathostomiasis?
Clinical disease of diarrhoea caused by intra mural larval stages of the nematode and mass emergence of hypbiotic larvae resulting in mucosal injury and inflammatory reaction. Migration of the larvae into the colonic mucosa and even presence of large larval numbers within the mucosa may also result in significant colonic inflammation and clinical signs. Common cause of chronic diarrhoea, an acute form also recognised. Clinical signs vary from weight loss, ill thrift, ventral oedema and soft faeces to severe acute enterocolitis (mass emergence of larvae). Acute diarrhoea mya progress to chronic diarrhoea. Often hypoalbuminaemic - may have elevated a and B globulins resulting in normal total protein concentration. FWEC likely negative as infection not patent at the time of disease.
What is the pathophysiology of carbohydrate overload?
Over eating of soluble carbohydrates - overwhelms the small intestinal digestive capabilities - high percentage enters large intestine - rapid fermentation by gram positive lactic acid producing bacteria - decreased caecal ph - death of gram negative bacteria - endotoxin release and absorption. high osmotic load in large intestine and pro secretory effects of acid luminal contents and inflammatory mediators results in diarrhoea.
What acid base status do acute colitis cases have?
Metbaolic acidosis
With hyponatraemia, hypochloraemia, hypokalaemia.
Endotoxemia is a term applied when an animal exhibits multiple adverse clinical signs including one or more of the following: fever or hypothermia, leukopenia, tachycardia, tachypnea, obtundation, and a change in gut motility. These physiologic effects are caused by what?
The cell walls of all Gram negative bacteria contain varying amounts of lipopolysaccharide, which in turn varies in its potency to create adverse reactions in animals. The signals have evolved on monocytes and macrophages to warn the animal when a Gram negative bacterium has gained access. When the reaction to this signal is overzealous, a cascade of adverse physiologic reactions can occur.
What is a possible complication associatied with colitis/endotoxaemia?
Hypercoagulability
What is the treatment for cyathostomes?
Fenbendazole for 5 days followed by ivermectin on day 6 OR moxidectin,
Give dexamethasone too
what are good dietary sourcesof protein for chronic diarrhoea?
Hay and alfalfa
What type of colics are large breeds predisposed to?
Large colon displacements
What type of colic are recently foaled mares prone to ?
Colonic torsions
Which colic conditions would result in gastric dilation/reflux?
acute grass sickness, ileus, small intestinal strangulating obstruction, proximal jejunitis.
What parameters on abdominal paracentesis are suggestive of inflammation?
Initial response of the peritoneum to inflammation or ischaemia is an increase in protein and fibrinogen levels in the peritoneal fluid. Fibrinogen >0.1g/l is suggestive of an acute inflammatory response or haemoabdomen. Acute ischaemia is characterised by a neutrophilia and increased erythrocytes. Acute inflammatory responses such as abscessation or bacteiral peritonitis may increase neutrophil counts without increasing RBC numbers. Peritoneal fluid may remain normal in horses with devitalised bowel if inflammatory debris is trapped e.g in epiploic entrapment and intussusception. Abnormalities include turbid, purulent or serosanguinous fluid, or digesta/blood in fluid. Total protein - normal is
What are the suggested indications for Surgery/euthanasia of colics?
Severe continuous pain showing no or only short duration of improvement with analgesia, pulse >60 progressively rising and weakening, progressive cardiovascular collapse, PCV >55, rectal findings positive for acute abdominal disease, progressive reduction in intestinal motility or continual gastric reflux, increasing abdominal distension.
Which enzymes are liver specific in the horse?
GGT and GLDH
What laboratory diagnostics are different in equine liver failure cf small animal?
Ammonia in horses not very useful, only in acute severe or end stage chronic disease. Blood ammonia levelsa re increased only in some cases of hepatic encephalopathy. Most affected horses are hyperglycaemic. but severely affected horses may be hypoglycaemic. Hypoproteinaemia and hypoalbuminaemia is rare in horses - most are hyperproteinaemic.
whhich breed does polysaccharide storage myopathy most commonly affect?
Quarter horses.
Horses present typically as a chronic case of tying up with signs often initiated following minimal exercise. there are abnormally high levels of the intracellular polysaccharide glycogen up to 4 levels of normal. Diagnosis based on histopathological findings. Genetic testing for glycogen synthase mutation
What is atypical myopathy/myoglobinuria?
Serious and frequently fatal. The recent evidence suggests that the toxic agent for this is Box elder tree and sycamore tree. Mainly occurs in young horses and ponies at grass, not related to exercise. Sudden onset muscle weakness and stiffness, afebrile and appetite and thirst remain, urine is red or chocolate coloured, most cases become recumbent and die. CPK and AST are markedly elevated. Myoglobinuria and haemoglobinuria present.
What is hyperkalaemic periodic paralysis in horses?
A syndrome of episodic muscular weakness associated with marked hyperkalaemia. Important problem in american quarter horses. Male horses seem to be affected to a greater extent than females. onset of HPP clinical signs typically between 1-5 yo. Episodes of weakness typically last less than 2 hours and affected horses often recover spontaneously. Muscle fasiculations, weakness, sweating, involuntary recumbency. Hyperkalaemia may only be present during an episode.
What is the treatment for hyperkalaemic periodic paralysis?
During episodes - i/v sodium bicarbonate, i/v dextrose, potassium free isotonic fluids, i/v calcium gluconate.
What are the most common cause of cystic calculi in the horse?
Calcium carbonate
What is the cause of urethral haemorrhage and haemospermia in stallions?
Due to tears in the proximal urethra at the ischial arch into the corpus spongiosum penis which is vascular rich and surrounds the urethra. There may be normal urine flow followed by bleeding at the end of urination due to contractions of the urethra that occur during this time, bleeding following ejaculation.
What is the current hypothesis for equine grass sickness?
Toxicoinfection with clostridium botulinum types C and D.
What are the clinical signs of grass sickness?
Dull, Anorexic, tachycardia (reflects hypotension and alterations in autonomic control of HR), bilateral ptosis, dysphagia, hypersalivation, slight drying of the mucous membranes, patchy sweating, mild to moderate abdominal pain, ileus due to damage to enteric nervous system, reduced inestinal sounds (absent if acute), muscle tremors over the triceps, flanks and quadriceps. On rectal - firm secondary large colon or caecal impaction.
What are the gross pathological findings associated with grass sickness?
Oesophageal erosions associated with reflux oesophagitis, gastric and small intestinal distension with fluid, impaction of the large colon with dry ingesta, black coating over firm ingesta, or if v chronic - lack of ingesta and apparent shrinkage of gastrointestinal tract.
What is proximal jejunitis (anterior enteritis)
Possible bacterial aetiology. rare in the UK. results in gastric and proximal small intestinal distension. often febrile, Increased gastric reflux of tomato soup fluid, decreased gut sounds. treatment is by decompression, fluid therapy, antibiotic therapy etc.
which Antibiotics and which bacteria are the most common causes of antibiotic associated diarrhoea?
Erythromycin, TMPS, penicillins, tetracyclines, clindamycin, lincomycin.
Bacteria - C perfringens, C difficile, Salmonella.
What are the predisposing causes to caecal impaction?
hospitalization, GA, Nsaid use, as well as same as large colon impactions. type 1 - impactions of dry ingesta filling the caecum
and type 2 - impaired caecal outflow due to motility dysfunction.
what are the predisposing factors to gastric impaction?
Ingestion of beet pulp, bran, dental disorders (incomplete mastication), terminal liver failure.
What portion of the stomach is most commonly affected with ulceration and why?
Squamous portion - no protective mechanisms against gastric acid. more common in high intensity training, roughage restriction, excessive concentrate feeding, NSAID use.
what is hyperlipaemia and why does this occur?
Hypertriglyceridaemia, fatty infiltration of body organs in resposne to stress and NEB, mobilisation of fat reserves. Common in small ponys and donkeys. clinical signs ; anorexia, depression, CNS signs, ventral oedema, colic, tachypnoea, tachycardia. dx - elevated blood triglycerides. may visually appreciate fatty appearance to plasma.
What are the predisposing factors to pelvic flexure impaction?
Reduced water intake, poor quality roughage, poor dentition
what is proliferative enteropathy?
Increasingly recognised in recent years, often occurs as outbreaks on breeding farms (4-6month olds affected), faecal oral transmission, causes profound hyperplasia of jejunal/ileal mucosa, resulting in secretory diarrhoea aand weight loss. cliical signs include ill thrift, weight loss, peripheral oedema, diarrhoea, colic.
What are the classical histological features of ragwort toxicity?
on biopsy: Megalocytes Periportal fibrosis biliary hyperplasia occlusion of central veins Exposure to massive doses may produce acute centrilobular necrosis.
describe the pathway of the pupilary light reflex?
Retina > optic N > optic chiasm > optic tract> midbrain> oculmotor nuclear > oculomotor n > ciliary ganglion > pupil
Describe the pathway of the menace response?
Lateral geniculate nucleus > occipital cortex > optic radiation > motor cortex >interneuron > facial nucleus > facial n > orbicularis oculi
What is the cauda equina?
Sacrococcygeal spinal cord segments, spinal nerve rootlets and roots of the cauda equine, sacral plexus and peripheral nerves to the bladder, rectum, anus, tail and perneum.
Lesions in cauda equine - degrees of hypotonia, hypalgesia and hyporeflexia of the tail, anus and perineal region, degrees of urinary bladder paresis and rectal and anal dilatation.
Where is the most common site for type 1 cervical vertebral malformation?
C3-C4 - seen in larger young horses. Developmental orthopaedic disease - vertebral canal stenosis/wedging/angular fixation.
What are the clinical signs of equine herpes myeloencephalopathy?
Often acute onset symmetrical ataxia & paresis. signs progress rapidly for about 2 days then stabilise. Pelvic limbs > thoracic limbs. Ataxia & cauda equine syndrome present. CSF often xanthochromic. It causes inflammation > vasculitis of arterioles in brain and spinal cord > multifocal haemorrhagic myeloencephalopathy.
What is the diagnostic test for EPM?
Serum immoblot test for antibodies, CSF immunoblot test for antibodies.
What is the Treatment for EPM?
Sulfonamides & pyrimethamine
How is west nile virus diagnosed?
Serum IgM antibody capture ELISA or PRNT (neutralizing IgG antibody) or immunohistochemistry on post mortem.
What may a foals CSF look like in septicaemia/meningitis?
Cloudy, with low glucose.
What is hypoxic/ischaemic encephalopathy? (neonatal maladjustment syndrome)
Seen more commonly in TB foals, after rapid parturition, but usually have a normal birth and signs delayed for a few hours to 2 dys, then start making noises such as barking, or dummy foals. must attend to passive transfer and nursing care.
What does fusarium sp mycotoxicosis cause in horses?
Acute forebrain necrosis.
Usually in mouldy feed.
Grave outlook.
What is polyneuritis equi?
Chronic granulomatous inflammation of the extradural nerve roots of many peripheral nerves. PNE can present first with cranial nerve signs. disease is progressive and early euthanasia should be considered. (sacral trauma far more likely),
What are the signs of west nile virus?
Most profound in non-vaccinated horses and include fever, anorexia, depression, somnolence (sleeping
sickness) to hyperesthesia, proprioceptive deficits, recumbency and cerebral/cranial nerve signs (head
pressing, propulsive walking, circling, head tilt).
Diagnosis:
• Clinical signs
• Abnormal CSF findings (elevated CSF protein and cell count)
• Definitive diagnosis based on serology or necropsy evaluation
Treatment:
• Primarily supportive and includes anti-inflammatory medications and fluid therapy
what are the clinical signs of wobblers?
Typically associated with symmetric ataxia, paresis, and spasticity
• Usually worse in the hindlimbs than the forelimbs
• Wide-base stance may be observed at rest along with proprioceptive deficits
• Stumbling, toe dragging and circumduction of the hindlimbs may also be observed
• Usually affects young horses (
How is EPM treated?
- Trimethoprim-sulfonamide & pyrimethamine: causes blockade of folate
metabolism in protozoa - Ponazuril (Marquis®): anti-protozoal drug believed to target protozoal organelle
(plastid) - Nitazoxinade (Navigator®): thought to inhibit electron transfer reactions
essential for energy metabolism
What is the normal result of the oral glucose absorption test?
1g/kg glucose in a 20% solution. the normal result is doubling or >85% of glucose in 2-3 hours then return to 4-6 hours. LEss than 15% absorption is strongly suggestive of severe SI pathology.
What tests can be used to measure insulin sensitivity and glycaemic status?
Fasting glucose and insulin - Increased levels of insulin provide evidence of insulin resistance, while increased glucose levels in a non stressed individual suggest severe insulin resistance/type 2 DM.
Oral glucose tolerance test. - blood insulin and glucose levels tested prior to administration and after administration of glucose 1g/kg. dDelay to return to normal (longer than 6 hours) suggestive of relative insulin resistance.
Combined intravenous glucose and insulin tolerance test - currently recommended as the most suitable dynamic test in clinical practice.
What is the normal amount a horse should drink?
50ml/kg / day - Polydipsia is >100ml/kg day = 50L for 500kg. Polyuria >50ml/kg/day = 25 L for 500kg.
What is the normal specific gravity in a horse?
1.020 - 1.050
Isosthenuric 1.008-1.014
Hyposthenuric
What electrolyte abnormalities would you have in the horse with kidney failure?
Sodium decrease, chloride decrease, calcium increase, phosphate decrease, potassium increase.
What is the cause of equine cushing’s disease/pituitary pars intermedia dysfunction? (PPID)
It is due to the overproduction of propriomelanocortin (POMC) peptides from pars intermedia. the resultant increase in adrenocorticotropin levels, coupled with the possible potentiating effects of other POMC peptides on ACTH, causes dysregulated cortisol secretion.
What are the clinical signs of Equine cushings disease?
Hirsuitism/hair coat changes - increased cortisol may lead to increased androgen production form the adrenal glands.
HYperhidrosis/sweating, Laminitis, lethargy/poor demeanour, fat redistribution, predisposition to infections, muscle wastage, PUPD due to hyperglycaemia (secondary DM), cortisol antagonism of ADH receptors in kidney, decreased ADH secretion via impingement in pars nervosa of pituitary gland.
What is the best test for diagnosing equine cushings disease?
Basal ACTH - single resting sample
TRH response test - basal cortisol sample, then inject TRH and cortisol sample 30 mins post injection.
Basal glucose elevated in a single resting fasted sample provides strong supportive evidence.
What is pergolide?
ergoline-based dopamine receptor agonist, used to treat equine cushings disease. It controls the output of ACTH.
What does pheynoxybenzamine do?
Decreases urethral sphincter tone thus facilitating urination with UMN problems. (a adrenergic blockers)
Which drugs are most likely to cause acute renal failure in the horse?
Aminoglycosides, NSAIDs, Polymixin,
Also - Heavy metals, acorns, Hb, Mb
What is idiopathic renal haematuria?
Mostly seen in arabs, sudden onset, blood from one or both ureters. unkown cause.
Where does chorioptes equi most commonly affect?
The distal limbs of heavily feathered horses.
Why do oxyuris equi cause disease?
Adult worms migrate frmo the small colon/rectum to lay eggs on the perianal skin causing pruritus/tail rubbing.
What is onchocercal dermatitis?
Seasonal dermatitis caused by onchocerca cervicalis microfilaria. The parasite is transmitted by culicoides spp and other biting insects. Larvae can be found in capillaries of unaffected horses but clinical cases result from type 1 and 3 hypersensitivity reactions. They cause alopecia and scaling of the head, neck, withers, chest and ventral midline.There is severe focal dermatitis with pruritis and exudation which may develop following the death of microfilaria in the skin after administration of avermectins.
What is rain scald?
a common skin infection caused by dermatophilus congolensis, causes exudation, matter hairs and scabs in areas wetted by rain, primarily the back/quarters. Classic paintbrush lesions. Tx with chlorhexidine, clip area, antibiotic ointment.
What species cause ringworm in horses?
Trichophyton equinum var equinum. Less commonly trichophyton verrucosum and trichophyton mentagrophytes.
What are the six types of sarcoids?
Occult, verrucose, nodular, mixed, fibroblastic, malevolan.
What are dentigerous cysts?
Swellings in the temporal region arising frmo tooth germ tissue.
What is habronemiasis?
Ulcerating cutaneous granulating nodules or wounds caused by the larvae of habronema muscae, habronema majus and drachia megastoma. The disease has several forms; Opthalmic habronemiasis - presence of yellow granules in conjunctivae and nasolacrimal duct
Cutaneous habronemiasis - larvae penetrate wet areas of the face, granulating wounds and the urethral process.
What is mud fever?
Dermatophilus congolensis - causes exudation, scabs and matting of hair of distal limbs. Mixed infections common. tx - chlorhexidine, remove exudate and scabs, fuciderm, flamazine.
What is pastern/cannon leucoytoclastic vasculitis?
A skin condition of the unpigmented distal limb. unpigmented skin involvement suggests role of UV light, although this condition is not thought to be a true photosensitisation. clinical signs include erythema, oozing and crusting of the white areas of the distal limbs. Can appear very similar to mud fever. clinical signs are often diagnostic but biopsies reveal leucocytoclastic vasculitis, vessel wall necrosis and thrombosis.
What is lymphangitis?
Inflammation of the cutaneous lymphatics usually but not always secondary to a bacterial infection obtained via a small cut/abraision. It affects the hindlimbs more commonly than forelimbs. usually causes marked swelling of the limb, lameness and serum exudation. Treatment is antibiotics based on culture results, NSAIDs/corticosteroids, potassium iodide and diuretics. Ulcerative lymphangitis is commonly associated with corynebacterium paratuberculosis, stpahylococcal spp and streptococcal spp infections.
What are the most common isolates from an endometrial swab in a mare?
Beta haemolytic streptococci E coli Other enterobacter Pseudomonas aurginosa Klebsiella pneumonia
What can be diagnosed on endometrial biopsy of a mare?
Endometritis
Periglandular fibrosis
Cystic glandular distension
