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Recently Discovered Parvovirus-Hepatitis Virus Subject of New AAEP Guidelines

The American Association of Equine Practitioners (AAEP) has published guidelines to educate practitioners about transmission, risk factors and clinical signs of a recently discovered virus capable of causing hepatitis in infected horses.

Two distinct etiologies of the virus – equine parvovirus-hepatitis virus (EqPV-H) – are recognized: biologic transmission and non-biologic transmission. Asymptomatic infection is common; only a small percentage of infected horses will develop clinical signs of liver disease.

According to the guidelines, signs of hepatitis in horses includes lethargy, not eating, jaundice, discolored urine, colic and neurological impairment such as head pressing, blindness, staggering or maniacal behavior. Death usually occurs within 72 hours.

“Drs. Thomas Divers and Bud Tennant of Cornell University College of Veterinary Medicine discovered that this novel parvovirus was associated with the disease ‘serum sickness’ in horses who had recently been administered a parvovirus-infected biologic,” Dr. Piper Norto, co-author of the guidelines, said in a statement from the AAEP. “Because of their seminal research and active ongoing research, information will be learned about this virus that will assist in making biologics safer for use in horses and help with diagnosis and treatment of this disease.”

EqPV-H is a recently discovered virus and the focus of rapidly evolving research. The AAEP says its guidelines reflect knowledge at the time of writing. Practitioners are encouraged to seek further consultation for questions regarding clinical cases of EqPV-H.

Equine Parvovirus-Hepatitis Virus Guidelines

The Equine Parvovirus-Hepatitis Virus Guidelines were authored by Linda Mittel, MSPH, DVM; Piper Norton, DVM, DACVIM; Joy Tomlinson, DVM, DACVIM; and Thomas Divers, DVM, DACVIM, DACVECC. The guidelines were reviewed and approved by the AAEP’s Infectious Disease Committee and board of directors.

Click here to view the guidelines, which can be downloaded or printed for future reference.

In addition to EqPV-H, AAEP guidelines for 21 other equine infectious diseases are available at In addition, two foreign animal disease guidelines—for African horse sickness and Glanders—can be found at

About AAEP

The American Association of Equine Practitioners, headquartered in Lexington, Ky., was founded in 1954 as a non-profit organization dedicated to the health and welfare of the horse. Currently, AAEP reaches more than five million horse owners through its over 9,000 members worldwide and is actively involved in ethics issues, practice management, research and continuing education in the equine veterinary profession and horse industry.