Hot spots can occur for a variety of reasons, some dogs seem pre-disposed to getting them. I have been very lucky, but did have one dog that got them every year. Best thing I have found is Gentain Violet, you can get it at your pharmacy and it is less expensive that "what the vet will sell you" or the feed store for that matter. May want to wear gloves and apply with a cotton ball to the area affected. It is the same thing as "blue-coat" for the most part. Nitrofurizone "puff" powder will also work wonders. As already stated 3/1 horse coat is also good, you have him on flea/tick control year round so that is a plus. Good Luck!!