we found with stud stock it is generally an issue that occurred when young (bacteria or similar).
Homeo is not a fast fix, but does seem to be a tool to used at times.
Niacinamide: Vit b3 (cream or similar) is another, but generally that is a symptom remover, depending if it is an organ issue. If a genuine skin issue it is great and fast turn around. Can even buy 100grams + for not much money, then add it to your own dog washing process