The clinical presentation of IADH includes anorexia, icterus, photosensitivity, discoloured urine and hepatic encephalopathy. Fever, ventral edema, jugular pulsation, dyspnea and weight loss may also be noted in some individuals. Diagnosis is made through clinical signs and symptoms, history of exposure to equine biologic products, and through serology showing increased GGT, AST and SDH. Treatment is mainly supportive care and the minimization of stress. may be required if the horse is manic but should otherwise be avoided as many sedatives are mildly hepatotoxic. Idiopathic acute hepatic disease may be avoided by reducing the chance of exposure to equine origin biologic agents such as TAT. One way to do this is to vaccinate all horses in a herd annually against tetanus infection, instead of administering TAT post partum.
Tyzzer’s Disease
Tyzzer’s disease is a sporadically seen hepatic disease of
.
It is caused by the Gram-negative bacteria Clostridium piliforme .
C. piliforme is a motile, spore forming bacteria that enters the body through the . From the intestines the bacteria gain entry into circulation where they move to the liver, the myocardium and the smooth muscle layers of the small intestine. The bacteria invade the muscle and liver cells, causing lysis of the cells and foci of necrosis in the tissues. Necrosis causes inflammation and dysfunction of the adjacent tissue. Transmission of C. piliforme is either through the ingestion of bacteria or the ingestion of spores. Spores can survive for more than one year at room temperature and for over an hour at 56.1 °C. seems to have no effect on the viability of spores. The resilience of the spores makes it difficult to thoroughly rid a property of contamination and it is common to see reoccurrence of Tyzzer’s disease on a single property year after year for several years.
Tyzzer’s disease occurs in foals
weeks old. Stress, poor sanitation, overcrowding and
corticosteroid use increases the likelihood a foal will develop Tyzzer’s disease.
The incubation period for C. piliforme infection is three to seven days. The clinical presentation includes depression, anorexia, pyrexia, icterus, diarrhea, recumbency, convulsions, coma and death. The escalation of symptoms occurs , over a few hours to a few days, and most foals are comatose or deceased before signs of sickness are noted. in the liver tissue. Serology may reveal increased GGT, SDH, AST, LDH and alkaline phosphatase levels, but serology alone is not definitive. Often a definitive diagnosis is not made until is carried out. Diagnosis can be made through liver biopsy showing hepatomegaly and necrotic
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