Good Morning and welcome! I am Dr. Loretta, a licensed veterinarian and I am happy to answer your question.
It is hard to know why Denby looses his mane in these places every summer since there is nothing itching these areas. It may be that he has a hypothyroid condition that centers in this area or that he has a form of mange or parasite that sticks in this area. I would have your vet check Denby's thyroid function and be sure to worm him with an Ivermectin wormer that would kill off any parasites. If this does not show anything, your vet can run a biopsy on these areas that may or may not show anything. This may be a hereditary condition specific for Denby that has no treatment.Does that make sense to you?
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