Seasonal Flank Alopecia

Flank alopecia is a frustrating but generally harmless loss of hair 
over the ribs, flanks and haunches of affected dogs. The exposed skin 
often becomes very dark and thickens and may develop a polished 
appearance. Conversely, flaking, scaling and dryness may also be 
present. Until recently, most cases were erroneously mistaken for a 
symptom of hypothyroidism and dogs with this variety of hair loss 
should be screened for thyroid disease. If the treating veterinarian 
determines the dog to be essentially normal with regards to it's 
endocrine system, then seasonal flank alopecia should be considered 
as the likely cause of bilateral symmetrical hair loss across the 
ribs, flanks and possibly hind quarters.
   There is no universally accepted or effective treatment for SFA. 
As it it rarely associated with discomfort or itching, it is more of 
an aesthetic issue although measures should be taken to protect the 
exposed skin from the elements, especially sunburn in the case of 
light skinned dogs. Use of melatonin and/or zinc supplements have 
been reported helpful anecdotally.
   As the name implies, the condition is seasonal, most often 
beginning in mid to late winter. This has led to the hypothesis that 
it is triggered by a lack of exposure to adequate amounts of natural 
light. This has led some owners to provide artificial full spectrum 
light in  indoor areas wherein the affected animals spend 
considerable amounts of time. Anectdoctal evidence suggests this may 
decrease at least the severity of hair loss. The condition will 
typically begin to resolve late spring and improve of disappear by 
mid summer but will often recur the next winter