Canine Alopecia Areata: A Retrospective Study of Clinical, Histopathological Features and Treatments in 14 Dogs.

Background: Alopecia areata (AA) is an autoimmune disease resulting in nonscarring hair loss. Limited data are available on the treatment and prognosis of canine AA.

Hypothesis/objectives: The goal of this retrospective study was to describe the clinical and histopathological features and treatment outcomes of 14 canine AA patients.

Animals: 14 dogs diagnosed with AA.

Materials and methods: Inclusion criteria were: (i) clinical lesions of leukotrichia and/or alopecia lacking erythema, crusts, or excoriations; (ii) no current systemic immunosuppressive therapies; (iii) histopathological confirmation of bulbitis; and (iv) availability of histopathological slides for review.

Results: Eleven dogs had a history of concurrent pruritus; five were previously diagnosed with atopic dermatitis. Lesion distribution spanned the face, dorsal cranium, and extremities. Skin biopsies were evaluated. The percentage of anagen bulbs affected was graded on a severity scale based on the diameter of cellular infiltrate. Seventy-one percent (95 of 134) of anagen hair bulbs were affected. Peribulbar cells consisted of lymphocytes in all dogs, plasma cells (in 13), eosinophils (in seven), macrophages (in six) and neutrophils (in six). Clinical outcomes were available for 12 dogs; follow-up ranged from 2 months to 7 years. Oral ciclosporin was the most prevalent treatment (eight dogs); six had partial hair regrowth and two had complete hair regrowth. Evidence of relapse was seen in four dogs when ciclosporin was tapered or withdrawn. Oral oclacitinib was effective in two dogs with partial and complete hair regrowth observed after 3 and 5 months, respectively. Spontaneous remission was reported in two dogs (14%).

Conclusion and clinical relevance: Canine AA is a chronic, relapsing disease often warranting long-term treatment.