Equus caballus papillomavirus 8 (EcPV8) associated with multiple viral plaques, viral papillomas, and squamous cell carcinoma in a horse.

BACKGROUND: Equus caballus papillomavirus 8, a recently discovered virus, has been reported to cause generalised papillomavirus in horses.

OBJECTIVES: To describe a case in which multiple viral plaques, viral papillomas, squamous cell carcinoma (SCC) in situ and invasive squamous cell carcinoma (ISCC) were associated with EcPV8 in a horse.

STUDY DESIGN: Case report.

METHODS: A 16-year-old mixed breed horse presented with dozens of raised crusted papular to nodular lesions over a course of 4 years. Masses had been surgically excised four times and cisplatin beads and emulsion were implanted on three different occasions; however new masses continue to develop in sites of previous masses as well as new sites.

RESULTS: Multiple viral plaques, viral papillomas, SCC in situ and ISCC, localised to the inguinal region, were diagnosed via histopathology. EcPV8 DNA was detected via PCR.

MAIN LIMITATIONS: Since only a few cases have been reported, we do not know the incidence of EcPV8 nor how often it may be associated with SCC in situ or ISCC without further study.

CONCLUSIONS: This is the fourth reported case of viral papillomatosis in the context of an EcPV8 infection in a horse. This is the first case in which SCC has been associated with EcPV8.