Canine papillomavirus types 1 and 2 in classical papillomas: High abundance, different morphological associations and frequent co-infections.

•Canine papillomavirus types 1 and 2 (CPV1 and CPV2) were very prevalent in benign non-plaque papillomas.•CPV1 and CPV2 DNA was often co-detected in papillomas.•CPV L1 antigen was expressed in skin and oral, exophytic and endophytic papillomas.•Histopathology and immunohistochemistry results aligned well in viral non-plaque papillomas.•Eyelid and conjunctival papillomas were often not papillomavirus-associated.