25 Canine recurrent flank alopecia
Canine recurrent flank alopecia is characterized by symmetrical seasonal hair loss affecting the thorax and flanks. In the past, it has been referred to as seasonal flank alopecia, canine idiopathic cyclic flank alopecia and cyclic follicular dysplasia. The condition mimics other endocrine disorders but the aetiology of canine recurrent flank alopecia is not known. There is seasonal hair regrowth in most dogs affected by this condition; however, in a small number of cases it may only be partial, or even non-existent. Clinically, canine recurrent flank alopecia is most often confused with hypothyroidism and, being only an aesthetic problem, it is important to distinguish between the two at the first instance to avoid unnecessary lifelong therapy. This report describes such a case.
Most cases are presented for the alopecia, which appears to be visually more marked because of the hyperpigmentation. Most dogs do not exhibit signs of pruritus unless there is secondary pyoderma. The affected dogs are healthy and usually the onset of the condition is of short duration.
Generally the alopecia is bilaterally symmetrical, mostly involving the lateral thorax and flanks, but in some dogs it may also affect the dorsal aspects. In a minority of cases, it may also involve the bridge of the nose, convex aspects of the ears, the tail base and the perineum. The alopecia is usually irregular but well demarcated, and both primary and secondary hairs are lost. On regrowth, a change in hair colour – lighter (aurotrichia) or darker (melanotrichia) – may be evident and, in some dogs, the new hair is dry, coarse and brittle. General physical examination in all cases is unremarkable, unless there is a concurrent disease.