Hepatobiliary Disease in the Horse Flashcards
What kind of history of disease might predispose horse to liver disease?
Previous GI disorders
What is Theiler’s Disease? What are the clinical signs? How rapidly do clinical signs progress?
Acute hepatic necrosis affects adult horses
clinical signs: nonspecific, many signs
(diarrhea, anorexia, fever, lethargy, neurological signs, etc)
Clinical signs progress quickly over 2-7 days
What is the cause of Theiler’s disease?
Unknown
Commonly associated with administration of tetanus antitoxin, plasma, blood products, etc. but horses can also develop symptoms from coming in contact with horses who have received the toxin
Also thought to possibly have a viral origin (equine parvovirus)
What kind of treatment is indicated for horses with Theiler’s Disease? Do all horses recover?
Supportive treatment for clinical signs
Not all horses recover
Some do well with supportive care, some are not so lucky
Which values are elevated with subclinical Theiler’s Disease?
↑GGT/AST for months
What is seen on histopathology in Theiler’s Disease?
centrilobular hepatocellular necrosis/lymphocytic infiltrates
What is Tyzzer’s Disease? What is the agent which causes Tyzzer’s Disease? How is the infection acquired?
Acute hepatitis/septicemia which affects foals 1-6 weeks old
Caused by Clostridium piliforme
Acquired by feco-oral route from carrier mares (foals perform coprophagia)
What are the clinical signs of foals with Tyzzer’s Disease? How do they usually present?
Severe hypoglycemia
Present comatose +/- seizures
What is observed on PME of a foal with Tyzzer’s Disease?
Icteric and grossly swollen liver with multiple pale necrotic areas
How is diagnosis of Tyzzer’s usually made?
Fecal PCR available, but most diagnosis made at PME
What is the prognosis of a foal with Tyzzer’s? What is the recommended treatment?
Poor prognosis
Attempt treatment with Oxytetracyclines, Penicillin
What predisposes ponies and donkeys to hyperlipemia?
Obesity
Why are pregnant or lactating ponies more likely to develop hyperlipemia?
Negative energy balance
What should you think of as a cause for hepatic disease if multiple horses on farm are affected? Where do you need to check?
Exposure to toxic plants
Check the fields
What in the diet can cause liver disease? What do you need to check?
Mycotoxins/moldy corn (Aspergillus) can cause liver disease
Hay may be contaminated with toxic plants (Senecio - Ragwort)
Check feed stores
How does ragwort poisoning occur? What is the prognosis?
Ragwort contains toxic compounds which can cause poisoning to horses if eaten in any state. Ragwort can damage the liver, which may eventually result in severe disease and even death. Ragwort is a common weed and horses may ingest it while grazing. There is no definitive cure, guarded prognosis.
At what % of liver damage does failure occur?
Failure occurs when 50-70% of liver function is lost
What do most horses with hepatic failure present with?
Hepatic encephalopathy
What causes photosensitization in horses with hepatic disease?
Photosensitization - accumulation of the photodynamic agent phylloerythrin (from plant material which horse eats), which travels up toward the skin
What % of the liver can you image with ultrasound? What can you assess about the liver with ultrasound? What kind of sampling can you perform with U/S guidance?
Can only image ~20% of the liver
Hepatomegaly, dilated bile ducts, choledoliths, abscesses and neoplasia (also useful for guiding liver biopsy)
When should you avoid liver biopsy?
If suspected liver abscess - may miss focal lesions
What are the general principles of treatment of hepatobiliary disease in horses? what does treatment depend on?
Primarily supportive treatment based on clinical signs
Depends on whether the horse is in hepatic failure or not