Equus caballus papillomavirus type 2 (EcPV2) in co-occurring vulvar and gastric lesions of a pony.

This research article reports the first known case of a pony with both vulvar and gastric lesions caused by Equus caballus papillomavirus type 2 (EcPV2), a virus believed to cause squamous cell carcinomas (SCCs) in horses.

Introduction and Case Description

The authors begin by explaining that squamous cell carcinomas (SCCs) are the most common type of malignant tumor found in horses. Typically, these tumors develop on areas of non-pigmented skin or the muco-cutaneous areas such as external genitalia. Stomach SCCs are less common. It is becoming increasingly clear that a virus known as Equus caballus papillomavirus type 2 (EcPV2) plays a role in causing genital SCCs in horses.

The unique case at the heart of this paper is a 20-year-old, mixed-breed female pony. The animal presented with simultaneous vulvar papilloma and in situ carcinoma as well as a gastric SCC.

Findings and Results

• Both the vulvar and stomach lesions were tested and confirmed to be positive for EcPV2. This was done via DNA sequencing.
• The researchers observed E6 mRNA expression in both the vulvar lesions and the gastric SCC. The L1 mRNA, meanwhile, was only noted in the vulvar tumor.

Significance of the Study

The authors claim that this is the first documented instance of a horse displaying EcPV2-caused SCCs in both the vulva and the stomach. Therefore, it modifies previous understanding that EcPV2 primarily causes SCCs in genital areas.

The findings suggest that there could be greater prevalence and a broader role for EcPV2 in equine tumors than was previously understood.

Further Studies

However, the authors advice caution, noting that additional research is necessary to truly understand the prevalence of this viral type and its role in equine tumors, highlighting the need to replicate findings to confirm their immediacy and extending the study population to ensure the generality of the results.