What type of allergy testing has the dog had? Intra Dermal Testing is the most accurate. By shots, the only shots I know of that work are Allergen Specific Immunotherapy.
It can take a while to see results, as much as a year, but it is wonderful when it works.
Maybe the vet that is treating him for hypothyroidism could recommend a
specialist/dermatologist. I would be very leary of any mail-in saiva or hair tests, I have heard that they are inaccurate
/forums/search/allergies/ via search engine, you may find some tips.
