Hepatitis in horses

Abstract

The main causes of hepatitis in horses include serum hepatitis, cholangiohepatitis and chronic active hepatitis with occasional cases of haematogenous bacterial hepatitis (e.g., Tyzzer's disease in foals), abscesses, viral hepatitis, parasitism and chronic infiltrative inflammatory disease. Not all cases of hepatitis will be clinically apparent due to the large reserve capacity of the liver. However, signs of marked hepatic insufficiency and hepatic encephalopathy reduce the likelihood of a successful outcome. Serum enzymes including alkaline phosphatase, aspartate aminotransferase, γ glutamyltransferase and glutamate dehydrogenase offer an approximate reflection of hepatic damage whereas functional indicators such as bile acids, bilirubin, albumin, globulins, urea and ammonia may provide more prognostically useful information. Nevertheless all serum biochemical parameters have significant limitations in terms of sensitivity or specificity. Liver biopsy, when guided by ultrasonographic images, offers the optimal safe and effective means of investigating suspected hepatitis in horses and will provide useful diagnostic and prognostic information in addition to aiding selection of therapeutic choice. General and supportive care for equine hepatitis cases includes fluid therapy, antipyretics and dietary management comprising small frequent feeds of low fat, good quality protein and cereal based feeds such as grass, good grass hay, dried proprietary chaffs, alfalfa, processed wheat/maize and B vitamin supplements. Care should be taken to ensure that supplements do not contain potential hepatotoxins (e.g., iron). Specific therapy is usually selected on the basis of biopsy findings and may comprise antibacterials, anthelmintics, glucocorticoids and lactulose.