Actually, it could be a form of alopecia 
Alopecia areata
Thought to be an autoimmune disorder
Symptoms: Patches of hair loss especially on head, neck, and body; no itching
Diagnosis: Microscopic examination of hairs; biopsy
Treatment: Usually recover spontaneously
I found that on this site - it could give you some ideas to discuss with your vet: http://www.peteducation.com/article.cfm?cls=2&cat=1593&articleid=421
Alopecia areata
Thought to be an autoimmune disorder
Symptoms: Patches of hair loss especially on head, neck, and body; no itching
Diagnosis: Microscopic examination of hairs; biopsy
Treatment: Usually recover spontaneously
I found that on this site - it could give you some ideas to discuss with your vet: http://www.peteducation.com/article.cfm?cls=2&cat=1593&articleid=421
Alopecia is frequently a symptom, not a condition. So you have to find out what the cause is before you can treat it.