Naturally acquired equine parvovirus-hepatitis is associated with a wide range of hepatic lesions in horses.

The research explores the link between equine parvovirus-hepatitis (EqPV-H), particularly its prevalence and severity, and various liver conditions in horses, since EqPV-H has been identified as causing Theiler’s disease – a severe liver condition in horses.

Overview of the Study

• The main objective of the research was to determine the prevalence and intensity of EqPV-H infections from a range of liver samples received for diagnostic studies.
• The samples evaluated for this study were older liver samples preserved through formalin-fixed, paraffin-embedded (FFPE) methods, collected between the years 2007 and 2022 by Cornell University and University of California, Davis.
• All samples were evaluated regarding 15 individual histologic features and also examined by EqPV-H hybridization.

Key Findings

• EqPV-H was detected in approximately half of the samples, indicating a high prevalence.
• Most of the EqPV-H-positive samples exhibited several common histologic features such as death of individual hepatocytes, lobular infiltrates, portal infiltrates, and ductular reaction.
• There were some specific histologic features like centrilobular necrosis, portal infiltrate and individual hepatocyte death which were linked to high viral load.
• Other features like neutrophil infiltrates, bridging fibrosis, and portal edema have a negative association with a high viral load.
• Testing was done for equine hepacivirus using PCR, another potential cause of hepatitis in horses, only very few samples were positive for it, suggesting that the effectiveness of this method of testing for FFPE tissues is questionable.

Conclusion

• Overall, the study suggests that EqPV-H infection is common across different kinds of liver pathologies in horses.
• Therefore, EqPV-H should be considered as a potential cause of other forms of hepatitis, beyond just Theiler’s disease in horses.