Anal fibropapillomas containing bovine papillomavirus type 2 DNA in two groups of heifers.

CASE HISTORY Anal warts were observed in heifers in two unrelated groups of animals. Heifers in one group developed visible warts 4 months after manual rectal examination and heifers in the other group developed warts 5 months after examination using a hand-held rectal ultrasound probe. CLINICAL FINDINGS Large exophytic proliferative anal masses were observed in 5/15 (33%) heifers in one group and 13/149 (9%) heifers in the second group. Heifers in the second group were also noted to have similar masses on the underside of the tail at sites previously used for venepuncture and some of the heifers had skin warts. Despite the large size of the anal masses, none of the heifers showed clinical signs of systemic illness. HISTOPATHOLOGICAL FINDINGS An anal mass was removed from one heifer in each of the two groups. Sections from both masses showed hyperplastic epithelium covering a proliferation of well-differentiated fibroblasts consistent with fibropapillomas. Small numbers of cells within the epidermis had clear cytoplasm with clumped keratohyalin granules. MOLECULAR BIOLOGY Bovine papillomavirus (BPV) type 2 DNA was amplified from both fibropapillomas by PCR. DIAGNOSIS Multiple anal fibropapillomas associated with BPV-2. CLINICAL RELEVANCE Bovine anal fibropapillomas have only been reported in heifers that have undergone rectal examination, and infection of anal microabrasions in an immunologically naïve animal appears to be associated with disease development. The source and method of spread of BPV-2 within these groups could not be determined. However spread of BPV-2 within the groups by the veterinarian performing rectal examinations may have been most likely. While these fibropapillomas had a dramatic appearance, like fibropapillomas elsewhere on the body, they did not have any significant effect on the health of the affected heifers. As these lesions can be diagnosed by clinical examination and self-resolve without treatment, it is important that veterinarians are aware of this rare manifestation of papillomavirus infection of cattle.