Conditions or ailments that are the cause of a problem that you see - your observation.

Your vet may diagnose

Hepatic Encephalopathy

Synonyms: Ammonia Toxicity


Hepatic encephalopathy is abnormal brain function and behavior caused by the buildup of natural toxins in the body when the liver has failed to detoxify or remove them from the blood. The liver is vital for the conversion of certain metabolic waste products into less toxic products that are removed from the body.
Ammonia is a product of the breakdown of dietary protein. In normal healthy animals, the liver converts ammonia into urea, which is excreted in urine. If the liver is damaged, it loses this function and these toxic waste products build up in the blood.

Hepatic encephalopathy happens with severe liver failure. In horses suffering from liver failure, blood ammonia and other toxic substances build up in the blood, body and brain tissue. This affects brain function, causing signs similar to those associated with some other brain diseases.

DIAGNOSIS of liver failure requires blood testing to measure liver function, levels of toxic products ,building up in blood.

TREATMENT of liver failure is mostly nursing care, removal or treatment of the agent or the process that is damaging the liver. Dietary management (usually reduced protein) to reduce the production of ammonia and other toxic byproducts is an important part of treatment.

my vet's role



Other conditions or ailments that might also need to be ruled out by a vet.

Very Common
Less Common
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Horses that have liver disease severe enough to cause hepatic encephalopathy generally have a poor prognosis for survival.

my role


I might observe

You might make these observations when a horse has this condition.

Very Common
Less Common
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Questions To Ask Your Vet:
  • Could my horse's behavior relate to loss of liver function?
  • How do I need to feed my horse in order to minimize buildup of toxic products?

Liver disease must be treated as aggressively as possible to prevent buildup of toxins and neurologic dysfunction.

Author: Doug Thal DVM Dipl. ABVP