Multiple perianal infundibular follicular cysts in a dog.

This case report describes a 7-year-old male cocker spaniel dog with multiple perianal infundibular follicular cysts. Clinically the dog had moderate anal sacculitis, peri-anal pruritus causing it to 'scoot' and lick the area. On examination of the perianal area, there were over 100 firm, well circumscribed papules, ranged from 0.2 to 0.5 cm in diameter with a central pore, and were found in the perianal region. Alopecia was present in the perianal region. The skin tissue in the perianal region resected surgically was submitted for histological examination. Microscopically, the tissue revealed multiple dilated cysts filled with keratins and the papules corresponded to infundibular follicular cysts. The affected dog showed moderate anal sacculitis. Anal sacculitis commonly causes repeated scooting or licking the area around the anus. Therefore, the multiple follicular cysts in the present case appear to be primarily a sequela to chronic external trauma to the perianal area, probably in response to anal sacculitis. To the best of the authors' knowledge, the present report is the first documented case of multiple perianal infundibular follicular cysts in a dog.