Equine Flashcards
(48 cards)
What can cause haemolysis in horses?
Neonatal isoerythrolysis
Infections
Drugs
Toxins
Autoimmune HA - relatively rare in horses
What are the two common causes of hyperbilirubinaemia in horses?
Anorexia
Acute hepatocellular disease
What percent of normal horses will look mildly icteric?
10-15%
What is the most common cause of icterus in horses?
Anorexia
What three things should be eliminated before thinking liver disease with an icteric horse?
Not anorexic
Not a foal
Not pale
What are the six functions of the liver?
Protein metabolism
Carbohydrate metabolism
Lipid metabolism
Detoxification
Immune system
Bile excretion
Why is hepatic disease not always followed by hepatic failure?
Liver has capacity to regenerate
Various functions giving varied clinical signs
What are the six common signs of liver disease in horses?
Depression
Anorexia
Colic
Abnormal behaviour
Weight loss
Icterus
What are the six less common signs of liver disease in horses?
Photosensitization
Diarrhoea
Bilateral laryngeal paralysis
Haemorrhagic diathesis
Ascites
Dependent oedema
Describe how photosensitization occurs with horses and how the liver is involved
Phylloerythrin formed by bacteria in gut
Absorbed, conjugated and excreted by the liver
With liver dysfunction increased levels of phylloerythrin
Exposure to UV light causes cell membrane damage and necrosis
Lesions occur in areas of non-pigmented skin as UV light absorbed more efficiently
What four things can be used to diagnose liver disease?
Clinical signs
Blood work
Ultrasonography
Biopsy
What are the three liver specific tests that can diagnose liver disease?
Increased bile acids
Increased SDH
Increased GGT
What percent of the liver can be imaged with ultrasonography in horses?
20%
What things could be seen on an ultrasonography in the liver in horses?
Dilated bile ducts
Choleliths
Abscesses
Neoplasia
What three things can a hepatic biopsy provide information for?
Diagnosis
Prognosis
Treatment options
What are the general principles for treatment of liver disease in horses?
Primarily supportive
Maintain animal until liver regenerates
With severe fibrosis regeneration unlikely
Correct fluid deficits and acid-base imbalances
Provide intravenous glucose if horse anorectic
Antibiotics if suspect bacterial aetiology
Anti-inflammatories
What is the treatment for hepatic encephalopathy in horses?
Sedation
Mannitol/hypertonic saline: cerebral oedema
Oral lactulose: limit ammonia absorption
Oral BCAA
What dietary modifications should be provided to a horse with liver disease?
High carbohydrate with limited protein
Protein rich in branched chain amino acids
Need to provide sufficient protein to ensure malnutrition does not occur
What are some recommended diets for a horse with liver disease?
Beet pulp
Cracked corn
Molasses
Sorghum, bran or milo
Oat hay
What anti-inflammatories can be provided to a horse with liver disease?
NSAIDs - flunixin meglumine
DMSO (dimethyl sulfoxide)
Corticosteroids - dexamethasone/prednisolone
Pentoxifylline
What is the main cause of pyrrolizidine alkaloid toxicity?
Ragwort poisoning
Describe the pathogenesis of pyrrolizidine alkoloid toxicity
Pyrrolizidine alkaloids metabolized by liver to toxic pyrrole derivatives
Pyrroles are antimitotic
DNA becomes cross-linked
Pyrroles bind to nucleic acid and proteins within hepatocytes
Cells can’t divide leading to megalocyte production
Proceeds to death and fibrosis
What are the clinical signs of PA toxicity?
Non-specific - diagnose upon biopsy with megalocytosis present
What is the prognosis for PA toxicity in horses?
Poor
Typically death within 10 days of clinical signs of liver failure
- Regeneration not possible if fibrosis present
