This is old but wanted to make certain I remedy was found.
This is an allergy. Found at feed store a product for the itching.
my lab did the same thing. he had food allegies. vet recommended duck and potatoe. products that are in most otc dog foods. helped tremendously.
My lab did the same thing, she had chewed the hair off her tail and the vet said it was a staff infection
he gave me antiabiotics and i also use dog shampoo that has aloe and oatmeal, works wonders
Do ask your vet about the hair loss
I agree with Jay - use dog shampoo - he could have dry skin, there's dog conditioners too that you can use. Have the vet check it out. Check for fleas or anything like that.
Sometimes "people shampoo" just doesn't work for dogs because of the dyes and perfumes. The best dog shampoos have virtually no smell to them. Call your vet for a recommendation. Have you throroughly checked the tail for signs of fleas or skin infection? He may need to be checked for mange or fungal infection if that hasn't been done yet.