Chronic hepatitis in horses with persistent equine hepacivirus infection.
Authors: Jager Mason C, Luethy Daniela, Shallop Samantha, Cathcart Jessica, Divers Thomas J, Tan Jean-Yin, Beasley Erin McConachie, Johnson Philip, Leduc Laurence, Smith Claire, Jamieson Camilla Anne, Magdesian K Gary, Van de Walle Gerlinde R, Tomlinson Joy E
Journal: Equine veterinary journal
Summary
# Equine hepacivirus and chronic hepatitis: what practitioners need to know Equine hepacivirus (EqHV), a virus structurally similar to human hepatitis C, has long been a poorly understood entity in equine medicine; this case series of 19 horses documents the first substantial evidence that persistent EqHV infection can trigger chronic hepatitis with liver damage patterns strikingly comparable to those seen in infected humans. Researchers retrospectively and prospectively identified horses meeting strict criteria: persistently elevated liver enzymes, histopathological confirmation of chronicity (particularly fibrosis), and documented persistent EqHV viraemia over median periods of 14.8 months' viral shedding and 18.4 months' active hepatitis. Liver biopsies revealed hallmark changes including fibrosis, lymphocytic infiltration, lymphoid aggregates, and hepatocyte death; whilst bacterial cholangiohepatitis accounted for one case, no other definitive cause was identified in the remainder, though concurrent bacterial infection, equine parvovirus-hepatitis, and equine multinodular pulmonary fibrosis were commonly documented. Although causation cannot be definitively established from this data, the clinical and pathological parallels with chronic human HCV strongly suggest EqHV warrants serious consideration in differential diagnoses of unexplained chronic liver disease. Practitioners should maintain heightened awareness of EqHV as a potential driver of progressive hepatic dysfunction, particularly in horses presenting with sustained elevations in liver biomarkers and appropriate risk exposure, though further research into transmission routes and treatment efficacy remains essential.
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Practical Takeaways
- •Horses with persistent EqHV infection may develop chronic hepatitis and liver failure with clinical presentation similar to human hepatitis C; screening and monitoring of serum liver biomarkers should be considered in suspected cases
- •Histopathological liver biopsy showing fibrosis, lymphocytic infiltration, and necrosis in an EqHV-positive horse suggests chronic hepatic disease requiring long-term management and monitoring
- •Comorbid conditions (bacterial infection, equine parvovirus-hepatitis, multinodular pulmonary fibrosis) frequently occur with EqHV hepatitis, necessitating thorough diagnostic workup beyond EqHV detection alone
Key Findings
- •19 horses with chronic hepatitis and persistent EqHV infection had median hepatitis duration of 18.4 months (range 5.2-120) and documented viremia of 14.8 months (range 6.9-55.6)
- •Histopathological findings in horses mirrored chronic hepatitis C in humans, including fibrosis, lymphocytic infiltrate, lymphoid aggregates, and individual hepatocyte necrosis
- •Bacterial infection, equine parvovirus-hepatitis, and equine multinodular pulmonary fibrosis were frequent comorbidities in these cases
- •A direct causal link between EqHV viremia and hepatitis cannot be established from this case series data