Sorry you're kiddo is going thru this.
Visible skin/hair issues are always secondary to either allergies or a disease state. If there is truly visible hair loss that is not regrowing, then you'd def want to get a thyroid panel, and then also look at symptoms of Cushings and see if your dog has other Cushingoid symptoms besides just hair loss. If yes, then I'd explore that with your vet as well. Keep in mind though that most general vets are not skilled at diagnosing Cushings...it's a very complex disease. Keep us posted please
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