Equine Viral Hepatitis: Clinical Conditions and Epidemiology

Despite the wealth of information on viral hepatitis in people, the role of viruses in equine liver disease is just starting to be explored. While some causes of equine liver disease are well described, such as bacterial cholangiohepatitis and pyrrolizidine alkaloid toxicosis, many cases of both acute and chronic equine hepatitis have unknown etiology. It wasn’t until the development and application of unbiased next generation sequencing that putative hepatitis viruses of horses were first described. Equine parvovirus-hepatitis (EqPV-H) causes acute hepatic necrosis ranging from subclinical to fatal severity. Equine hepacivirus (EqHV; also known as non-primate hepacivirus, NPHV), a close relative of hepatitis C virus, causes mild acute hepatitis in resolving infections, and chronic fibrosing hepatitis in persistent infections. Both viruses are highly prevalent in equine populations worldwide and can be transmitted iatrogenically, with important implications for treatment with equine origin biologic products. This lecture will review the current knowledge for each of the two viruses, including disease manifestations, diagnostic testing, treatment and prevention, and prevalence and transmission.