Even zoeken op internet levert o.a. deze beschrijvingen op:

Over vlekken op onbehaarde/dun behaarde delen:
http://www.thehorse.com/articles/13828/why-the-white-spots

Over vlekken in de vacht:
https://www.vetstream.com/equis/Content/Disease/dis01380

Het eerste tekstje eindigt met de volgende positieve woorden:
"Lucky for your horse, it's just a depigmentation and doesn't do any harm. As an owner, remember that a horse isn't likely to look in a mirror and worry about his appearance! "