Maybe its genetic. A friend owns a WB that she breeds in house only. All of his offspring ended up getting, what looked like, a dirty, scaby rash that spread over time. It appeared on their socks only, not blazes. It was a PAIN to clean and clear up. Took a lot of Dex to do the trick. All of these rashes started when the horses were 2-3 years of age, lasted for a season or two and then just went away, never to return again. Never really got an answer on what it was or what caused it. We thought it was caused photo sensitivity, but can't confirm that.
This is what happens when you have democrats in office