Sebaceous adenitis is a suspected immune-mediated disease that targets and destroys sebaceous glands. This retrospective study evaluated the clinical presentation and incidence of sebaceous adenitis in Havanese dogs. Sebaceous adenitis was diagnosed in 35% (12 of 34) of Havanese dogs presented over a 5-year period. Onset of clinical signs occurred during young adulthood. Follicular casts were present in 92% (11 of 12) of affected dogs. Other common clinical signs included alopecia and hypotrichosis. The trunk, head and ears were commonly affected, with 67% (8 of 12) of cases having pinnal and ⁄ or external ear canal involvement. Secondary pyoderma was seen in 42% (5 of 12) of dogs. Histopathology revealed absent sebaceous glands in 83% (10 of 12) and a lymphoplasmacytic periadnexal infiltrate in 92% (11 of 12) of samples. Treatment included multiple modalities. Ciclosporin was prescribed in 83% (10 of 12) of cases. Other systemic therapies included vitamin A and fatty acid supplementation. Topical therapies included antiseborrhoeic shampoos and sprays, and oil soaks. Follow-up ranging from 2 months to 3 years was obtained in 67% (8 of 12) of dogs. Improvement ranged from minimal to marked, with better clinical response associated with longer duration of treatment. Owners with follow-up of more than 1 year commonly reported occasional flares of the clinical signs. This study found that sebaceous adenitis was a common diagnosis in Havanese dogs, that the ears were commonly affected and that a lymphoplasmacytic periadnexal infiltrate associated with absent sebaceous glands was frequently seen on dermatohistopathological examination.