I'm having a weird allergy with one of my dogs...his coat is thinning out on his head and face. Not patches...like a receding hairline. He initially had bald patches on his flanks also like mange but had negative test...I changed his diet...those bald patches went away...but his head has stayed the same. Its from the base of his skull...ears...around eyes...and muzzle. I'm clueless at the moment. I can't figure it out. Blood work is fine...negative demodex. No watery eyes...runny nose...stool is great...no sneezing...no ear infections. I dunno.