Seasonal flank alopecia (lack of hair) is a localized cyclic hair follicle growth abnormality that tends to occur in the fall or spring.  Some dogs loose hair in the late fall and regrow it spontaneously in the spring;  others do the reverse and lose hair in the spring.  Airedale terriers, English bulldogs, and Boxers are at higher risk, but the condition has been described in Miniature Schnauzers, Miniature Poodles, Wirehaired Pointing Griffons, Doberman Pinschers, Bouvier de Flanders, Scottish Terriers, and French bulldogs.  These dogs develop a non-scarring alopecia most often confined to the sides of the chest and lumbar area. The lesions are bilateraly symmetrical, single annular to multiple “rings” in shape, and have well-demarcated borders;  in addition, the skin is usually markedly darker or “hyperpigmented”.  Scaling and bacterial dermatitis may occur in the areas of hair loss.  In some dogs, only one side of the animal is affected, or one side is more severely affected than the other.  The spontaneous regrowth of hair that occurs in 3-4 months may consist of normal hair, or hair that is a different color, texture, or both.  In over 50% of the cases, the hair loss occurs at least twice in successive years.  To date, underlying causes, such as a hormonal disorder or allergic reaction, have not been identified.

There is currently no effective treatment for the seasonal or cyclic “follicular dysplasia”.  The prognosis is unpredictable in any given dog.  Some dogs continue to develop recurrent seasonal hair loss for years;  other dogs have an occasional year when the alopecia does not recur;  still other dogs eventually develop permanent alopecia in the affected sites.  The degree of alopecia is also variable with some dogs developing a virtually identical hair loss pattern year after year, and other dogs developing larger and larger areas of hair loss as the years go by.

Other diseases present with very similar signs including:  1) Cushing’s disease (hyperadrenocorticism); 2) Hypothyroidism;  3) Estrogen or testosterone imbalances; 4) Stress-induced hair loss;  5) Post-clipping alopecia;  6) Color-mutant alopecia ( i.e. blue Dobermans, fawn Irish Setters, blue whippets, blue dachshunds);  7) Pituitary dwarfism;  8) Hypovitaminosis A;  9) Burn or freezing scars;  10) Mange;  11) Cutaneous fungal disease;  12) Dermatophytosis; 13) Injection reactions;  or 14)  psychogenic alopecia.  Therefore, it is essential that a veterinarian examines the dog before one believes his or her dog has seasonal flank alopecia.  Most bilaterally symmetrical alopecias do need clinical management.

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