Hepatology - equine Flashcards
What are the functions of the liver?
Protein/carb/lipid metabolism
Bile excretion
Detoxification
Mononuclear phagocyte system
How much hepatic mass needs to be lost/not functioning to cause hepatic insufficiency?
80%
What is a sequalae of hepatic insufficiency?
Hepatic encephalopathy - neuro signs
What disease causes orange skin on a horse?
Cholangiohepatitis
What is regurgitation icterus?
Impaired excretion of bilirubin into the biliary tract
How does liver disease cause hepatogenic photosensitisation?
Increased blood conc of photodynamic agent - phylloerythrin
Phylloerythrin combined with IV creates free radicals which damage skin
How do you evaluate for liver disease in horses?
Serum bile acid concentration - very good screen for liver failure
Bilirubin - not a sensitive indicator, only increased in 25% of horses
What is different about the serum bile acid concentration testing in horses to small animal?
Dont have a gall bladder so dont need to do pre and post prandial
What change in protein synthesis do you see in the liver? What does it indicate?
Albumin level - if hypoalbuminaemic then means more than 80% of liver has been affected for more than 3 weeks
What are the liver enzymes in horses specific to hepatocellular disease?
SDH
GLDH
GGT
(ARG)
What equine liver enzyme has a major drawback?
SDH - doesnt survive in a tube
Which equine liver enzyme is the most sensitive indicator of hepatic disease/hepatocellular damage?
GGT
What are the drawbacks to GGT equine liver enzyme?
Higher in foals - from colostrum
Continues to rise for 1-2 weeks after liver improving
May not increase in chronic disease
What are the first line lab tests done if suspect liver disease?
GGT - evaluate for damage
Bile acids - evaluate function
When can you not do a liver biopsy in horses?
Hepatic lipidosis - will make liver shatter
If impaired clotting
What diagnostic imaging can you use to look at the liver?
Ultrasound
How do you do an equine liver biopsy?
Ultrasound guided tru cut
How do you treat hepatic insufficiency? How should you feed horses?
Supportive
High carb low protein diet, multiple small feeds, oat hay/grass
Paraffin/magnesium sulphate - reduce toxin absorption in gut
How can you tell the difference between acute and chronic disease in horses?
Difficult
Onset of signs can be sudden in both
Chronic disease may show hyperglobulinaemia, hypoalbuminaemia and fibrosis
What is theilers disease?
Acute hepatic failure caused by giving equine origin antiserum eg. tetanus antitoxin injection
How do you approach bacterial hepatitis?
Liver biopsy - culture, histology
Supportive therapy
4-6 weeks of appropriate antibiotic
What can be ingested by horses to cause chronic liver failure? What is the name of the disease it causes?
Ragwort - yellow plant
Megalocytic hepatopathy
How does ragwort cause chronic liver failure?
Cumulative toxicity - eaten over a long period of time
Stop hepatocyte division so cells enlarge - megalocytes
These die and get fibrosis causing liver failure
What are the clinical signs of megalocytic hepatopathy from ragwort?
4weeks-12 months after ingestion
Hepatic encephalopathy
Photosensitisation
Anorexia/weight loss
Icterus
What is the prognosis of megalocytic hepatopathy from ragwort?
Poor prognosis - fibrosis limits regeneration
What are the features of cholelithiasis in horses?
Intermittent signs of icterus, colic, weight loss
Dilated bile ducts on ultrasound
What is non-septic hepatitis in horses?
Inflammatory infiltrate without infection
What are some causes of non septic hepatitis?
Unknown aetiology - likely viral or toxins in hay
How do you treat non septic hepatitis?
Corticosteroids, azathioprine
What should you do after looking at liver enzymes and bile acids when investigating a suspected liver disease case?
Liver panel, clotting, biopsy
