No CPV detected in 99 canine Meibomian gland tumor samples; adenomas were smaller and had lower mitotic counts.

Meibomian gland (MG) tumors are common in dogs. Papillomaviruses have been detected in epithelial neoplasms across species, including those arising from the human MG, but their role in the development of canine MG tumors has not been investigated. The purpose of this study was to evaluate whether Canine Papillomavirus (CPV) contributes to MG tumorigenesis. A retrospective review of a Laboratory Information Management System (LIMS) was performed to identify cases of canine MG tumors submitted between 2019 and 2024. DNA was extracted from archival FFPE tissue scrolls, and PCR was performed using validated viral CPV-1 E6 and L1 primers. Clinicopathologic features including patient age and sex, tumor size, tumor laterality and location, presence of chalazion, mitotic count, and extent of surgical excision were evaluated. LIMS review yielded 106 cases of canine MG tumors, and 102 were histologically confirmed to be MG adenomas or epitheliomas. PCR was performed on 99 samples, and no viral amplicons were detected in any MG tumor. Dogs with adenomas were younger than those with epitheliomas. There were no differences in sex or alteration status between tumor groups, and Labrador retrievers and Poodles were overrepresented. There were no differences between tumor types in terms of laterality or upper vs. lower eyelid. Adenomas were smaller and had lower mitotic counts compared to epitheliomas. The presence of chalazion or completeness of the surgical excision was not different between tumor subtypes. While we confirm consistent morphologic and phenotypic differences between canine MG adenomas and epitheliomas, these results suggest that, unlike their human counterparts, neither tumor subtype is virally mediated.