As a veterinarian who works for an animal nutrition company,
I frequently have the opportunity to interact with customers who have questions
about health issues that may be nutritionally related. I frequently hear from
horse owners whose horse has developed white spots on their face, usually
around the muzzle and/or eyes. The conversation typically goes something like
this: “My horse suddenly developed white spots on his muzzle and around his
eyes. I read on the internet how this was called vitiligo or leukoderma and is caused
by a deficiency of vitamin A (or copper or zinc or iron or vitamin D or….). How
could this be since he is on Strategy® horse feed and excellent
pasture, and I know he is getting all the vitamins and minerals he needs? I
tried to find more information about this online, but couldn’t find much that
was very scientific. When I asked my vet, she told me that it was a cosmetic
problem that won’t affect his overall health and that not much is known about what
causes it or how to treat it. I’m confused, and don’t know what to believe or
what I can do about it. Can you help me?”
The confusion is understandable. There are at least two
distinct conditions which result in virtually identical outward clinical
appearance: depigmentation (loss of color) of pigmented bare (no hair cover)
skin. As a result, there is a great deal of uncertainty about which term should
be applied and what the inciting cause of the depigmentation may be. Therefore
the terms “leukoderma” and “vitiligo” are often used interchangeably, even
though leukoderma and vitiligo are definitely not the same. And misinformation
propagated on the Internet further muddies the waters.