Atypical dermoid sinus in a chow chow dog.

A case of multiple dermoid sinuses in the dorsal cervical and craniothoracic regions in an adult chow chow dog is described. One sinus did not open on the skin surface. This is the first reported case of the condition in this breed and the first time absence of the sinus opening on the skin is described. The use of the term pilonidal sinus to describe this condition is challenged.