AAEP Publishes Equine Viral Hepatitis Guidelines

Newly published Equine Viral Hepatitis Guidelines from the American Association of Equine Practitioners (AAEP) provides comprehensive information and instruction for equine veterinarians concerning transmission, risk factors, clinical signs, diagnostics and other considerations for two viral causes of liver damage in horses: equine parvovirus-hepatitis (EqPV-H) and equine hepacivirus (EqHV).  

 The guidelines document incorporates updates to guidance originally published for EqPV-H in 2021 along with new and corresponding guidance for EqHV, recently recognized as a cause of chronic hepatitis.  

 While EqHV infects approximately 40% of US horses, versus 15% for EqPV-H, most will clear the infection within 20 weeks and will not have clinical signs of liver disease or illness. Approximately 20% of horses infected with EqHV will develop persistent infection lasting beyond six months, and a small percentage of those will develop hepatitis over months to years. Affected horses can have subclinical disease or show signs of liver disease of varying severity. Treatment of clinically affected horses relies primarily on supportive care and treatment of liver dysfunction. 

“Both viruses can be present [horse is PCR positive] and not actively causing disease. Serial testing and early testing can help veterinarians interpret whether either virus is likely to be the cause of hepatitis,” said guidelines author Joy Tomlinson, DVM, PhD, DACVIM, assistant professor of large animal medicine at the University of Pennsylvania School of Veterinary Medicine.  

“If you diagnose a horse with hepatitis, I recommend either submitting the serum PCR right away or saving serum from the first visit in your freezer,” she added. “If you decide to pursue viral testing later, having that sample to compare to will be very helpful.” 

The Equine Viral Hepatitis Guidelines were reviewed and approved by the AAEP’s Infectious Disease Committee and board of directors. View the guidelines or save them to your mobile device as a PDF for future reference at https://aaep.org/resource/equine-viral-hepatitis-guidelines. 

AAEP members may also access the guidelines through the AAEP On-the-Go app; search “AAEP On-the-Go” at your app store to download. 

In addition to the Equine Viral Hepatitis Guidelines, AAEP guidelines for more than 30 equine infectious diseases and foreign animal diseases are accessible through the app and the AAEP Guidelines Library at https://aaep.org/guidelines-resources/resource-library/guidelines-library.  

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 5 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.