Prevalence and pathology of equine parvovirus-hepatitis in racehorses from New York racetracks.

The research suggests a common occurrence of equine parvovirus-hepatitis (EqPV-H) infections among New York racehorses, with a potential link to a serious equine disease — Theiler’s disease. Given that the virus was detected in a substantial number of horses, further studies are needed to investigate its impact on racehorse performance.

Introduction to Theiler’s Disease and EqPV-H

• Theiler’s disease, also known as equine serum hepatitis, is a rare but highly lethal disease that affects horses. The disease was typically associated with Equine Parvovirus-Hepatitis (EqPV-H).
• Despite a low incidence of Theiler’s disease, the prevalence of EqPV-H DNA in horses is high, with some regions recording up to 37%, implying that subclinical or persistent infection is common.

Study Design

• To figure out the prevalence and pathogenicity of EqPV-H infection in New York’s racetracks, DNA was extracted from preserved liver tissues of racehorses which were sent for necropsy to the Animal Health Diagnostic Center. This was part of the collaboration between the New York State Gaming Commission and Cornell University.
• A total of 191 liver samples from horses between 2 and 13 years old were examined, and the DNA was tested for EqPV-H using PCR (Polymerase Chain Reaction) and gel electrophoresis.

Findings

• Out of the total samples, 42 were found to be PCR positive, constituting 22% of the total samples. Moreover, 31 out of these 42 samples had positive viral nucleic acid hybridization in the liver cells, with 11 samples showing positive hybridization in necrotic liver cells along with inflammatory cells. These findings indicated an occurrence of active hepatitis.
• The results of the study show a positive connection between the detection of EqPV-H and both individual hepatocyte necrosis and hepatitis.

Conclusions

• These findings point out that EqPV-H presence and parvoviral-associated hepatitis are common among racehorses in New York racetracks.
• Given this high prevalence, the authors call for additional studies to further explore the possible link between EqPV-H infection and its potential impact on the performance of racehorses.