What is Equine hepacivirus (EqHV) (Liver Disease) 

Equine hepacivirus (EqHV) is one of the viruses causing liver disease. 

Clinical Signs: Horses infected with EqHV can develop a wide range of clinical signs, varying from inapparent or very mild illness to fulminant liver failure. It is not currently known why some dorses do not develop clinical signs while others are severely affected. 

Acute infection: Most horses infected with EqHV will clear the infection within 20 weeks and will not have clinical signs of liver disease or illness. Liver enzyme activities on bloodwork may or may not be transiently elevated and will normalize within 4-16 weeks.

Chronic hepatitis: Approximately 20% of horses infected with EqHV will develop persistent infection lasting longer than 6 months. A small percentage of those horses will develop hepatitis over months to years. Affected horses may show one or more of the following:

  • Lethargy
  • Anorexia
  • Weight loss
  • Elevated liver enzyme activities on bloodwork
  • Elevated blood ammonia and bile acid concentrations
  • Jaundice (yellow eyes and gums)
  • Photosensitization (sunburn of white skin)
  • Neurologic signs (altered behavior, head pressing, staggering, blindness)
  • Discolored urine
  • Colic 
  • Recumbency
  • Death 
  • NOTE: EqHV does NOT cause fever

Diagnosis: EqHV should be considered in horses with signs of liver disease. A definitive diagnosis of EqHV infection can be achieved using a PCR test on liver biopsies, serum, EDTA plasma, or whole blood. However, the presence of the virus does not always mean it is actively causing disease. 

Treatment: There is no approved treatment for EqHV infection. Asymptomatic horses do not require any treatment. Treatment of clinically affected horses relies primarily on supportive care and treatment of liver dysfunction. 

Prevention: There is no vaccine for EqHV. When administering equine biologic products (e.g., stem cells, plasma), it is best to administer autogenous biologics (made from the patient’s own blood), or biologics that have been tested and confirmed free of the virus.  The USDA APHIS Center for Veterinary Biologics (USDA APHIS CVB) currently does NOT regulate or test for EqHV in equine biologic products

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