Alopecia in a black Labrador retriever associated with focal sub-follicular panniculitis and sebaceous adenitis

A 6-year-old entire male black Labrador retriever was presented with nonpruritic multicentric, well-demarcated alopecia of 12-weeks duration. Skin biopsies from the margins of alopecic regions showed sebaceous adenitis and sub-follicular panniculitis. Biopsies from alopecic areas showed severe follicular atrophy with residual fibrous tracts, loss of sebaceous glands and lymphohistiocytic panniculitis beneath individual atrophic hair follicle groups. These features differed from previous reports of pilosebaceous diseases of dogs and appeared to extend the spectrum of inflammatory patterns in presumed immune-mediated adnexal diseases of this species. During the 12-month follow-up, there was partial hair regrowth without treatment but alopecia was permanent in the centre of larger lesions.