Have you ever heard of a horse losing its hair? And if so, what are the causes and treatments? Have you ever run across it happening as a reaction to supplemental feed? Our horse is losing his hair and his vet hasn’t figured out why. DG, Wyoming

Dear DG,

I’m sure your vet is steering you down the right path; this just sounds like a very unusual problem. Since I haven’t seen the horse, I would need to ask a few questions first:

• where is the hair loss occurring (the whole body or just certain parts of the body)
• is the hair breaking off or falling out from the follicle with the root still attached
• has the hair changed color (lighter or darker)
• is there any skin involvement (red, raised, bumps, oozy discharge/dry flakes)
• are there any other horses with the same signs

Of course, a full physical examination is important to determine if the overall health status of the horse has changed. Bloodwork may be necessary too. How old and what breed is the horse? Also, what do you do with him, that is, is he ridden and shown and if so, what is his monthly schedule of work, training, competing, traveling. Vaccination and deworming status are an important part of the baseline as well. What is the horse eating (hay, grain, supplements) and how he is kept (stall, turnout)? Any changes to his diet or environment may also yield clues.

It sounds like the cause isn’t obvious so the veterinarian is probably performing additional diagnostics such as skin scrapings, skin cultures and maybe even biopsies. While these tests may not pinpoint the exact cause, it is hoped they at least rule out certain conditions and narrow down the list of differentials. Visit www.merckvetmanual.com for more information and to learn what conditions may cause this. I hope you and your vet are able to figure this mystery out!