Adult-onset, noninflammatory alopecia can have many causes, including but not limited to hypothyroidism, hyperadrenocorticism, testicular tumors, hair follicle dysplasias, and telogen effluvium. There are also several clinically recognized "syndromes" of noninflammatory, acquired alopecia for which the cause is still unknown. Some of the better-recognized syndromes include recurrent flank alopecia, "alopecia X," and breed-related alopecia. Breeders of Chesapeake Bay retrievers have recently begun to recognize a distinct pattern of nonpruritic, noninflammatory, regional hair loss affecting the flanks, dorsum, axillae, and caudal thighs. A thorough investigation of 10 dogs with this disorder showed that the clinical signs are similar in both males and females. Endocrine testing revealed increased adrenal and sex hormone concentrations in 7 of 10 dogs. Histologic findings included follicular hyperkeratosis and plugging, follicular atrophy, and occasional melanin clumping with deformed hair shafts.
COMMENTARY: This syndrome has been recognized by veterinarians and breeders for years. It is similar to what is found in dogs with pattern baldness and follicular dysplasia. In addition, the histologic findings are almost identical to canine recurrent flank alopecia, but history can help rule out this disease because there is no seasonal regrowth in Chesapeake Bay retriever alopecia. The increased adrenal and sex hormone concentrations found on the "sex hormone panel" cannot be ignored, but it is still not clear if this is yet another breed with "alopecia X." Until normal laboratory values for intact and neutered Chesapeake Bay retrievers are established, the sex hormone assay should be interpreted with caution. So what should you do with a balding retriever? Look for a treatable disease and proceed with a standard noninflammatory alopecia workup (skin scrapings, fungal culture, impression smears, skin biopsy, and ruling out hypothyroidism and hyperadrenocorticism). This is a diagnosis of exclusion, and until a cause is determined, these dogs should not be used for breeding. If affected dogs are used for hunting, they should be fitted with a protective vest to prevent skin trauma, and if they spend significant time outdoors, they should be monitored for solar-induced skin lesions. Finally, intermittent adrenal function testing is recommended to monitor for overt adrenal disease.
Adult onset hair loss in Chesapeake Bay retrievers: A clinical and histological study. Cerundolo R, Mauldin EA, Goldschmidt MH, et al. VET DERMATOL 16:39-46, 2005.