PIGMENTED PLAQUES ASSOCIATED WITH PAPILLOMAVIRUS INFECTION IN DOGS - IS THIS EPIDERMODYSPLASIA-VERRUCIFORMIS

Two Pugs and two Miniature Schnauzers with multiple pigmented epiderma l nevi were investigated. The four dogs had pigmented cutaneous macula e and plaques. Histopathological evaluation showed papillated or digit ated epidermal hyperplasia with hypermelanosis and giant keratohyalin granules in the stratum granulosum. Immunohistochemical staining revea led papillomavirus group-specific antigen in the skin specimens from a ll four dogs. Electron microscopic study of the specimens from two dog s revealed numerous round viral particles within the nuclei of the ker atinocytes in the upper stratum granulosum. It was suspected that papi llomavirus was the etiologic agent of the lesions, and that Pugs and M iniature Schnauzers might be predisposed to infection. These findings indicate this canine dermatosis resembles epidermodysplasia verrucifor mis (EV) of humans, a rare chronic disease caused by human papillomavi rus. The potential for transformation of the lesions to squamous cell carcinoma is also suspected and discussed.