Alopecia areata (AA) afflicts 1% to 2% of people in the general population and usually causes patchy areas of complete hair loss on the scalp and other parts of the body. AA is suspected to be an autoimmune disorder directed against hair follicles. AA or AA-like disease has been reported in domestic animals, including dogs. Between 1994 and 1999, 25 client-owned dogs were diagnosed with AA. This study evaluated the clinical, histopathologic, and immunopathologic features of these dogs. Clinically, they had alopecia, skin hyperpigmentation, and leukotrichia. The lesions typically developed during adulthood and appeared first on the face and then the forehead, ears, and legs. Nineteen of the 25 dogs were reported as purebred, including 3 dachshunds, 2 beagles, 2 setters, 2 Labrador retrievers, and 4 German shepherds. There was spontaneous remission of alopecia in 60% of the dogs; the hair regrowth was often nonpigmented. The results of the histopathologic examination and immunofluorescence analysis were similar to the findings reported for human patients with AA.

COMMENTARY: Alopecia areata is a common hair-loss-producing skin disease in humans characterized by autoantibodies directed against hair follicle proteins. A similar disease has been recognized in mice and a variety of other mammals including the dog. The authors characterize this rare canine skin disease in 25 dogs. Hairloss was commonly bilaterally symmetrical and affected the face, temporal region, pinnae, and legs. Spontaneous remission occured in 60% of the dogs. Clinical, histopathologic, and immunopathologic similarities to the disease seen in humans were striking.

A natural canine homologue of alopecia areata in humans. Tobin DJ, Gardner SH, Luther PB, et al. J DERMATOL 149:938-950, 2003.