Dog Losing Fur

Question
Dr. Gotthelf,
    I have a 6 year old dog that is a Lab/Chow mix and usually once a year he needs to have a steroid shot for allergies (I don't know what he's allergic to because I can't afford the full battery of tests to find the root cause).  Lately though, the shots seem to have no effect as he is constantly 'chewing' and causing his fur to fall out.  I'm going to start putting aloe on his exposed skin to try and heal it along with 'bitter apple' to try and keep him from chewing/scratching so much.  Do you have any other suggestions as to what could be causing this ?  He is an inside dog and nothing has changed in my house since I got him.  I recently changed his food from his 'usual' to see if that could have been the problem.

Thank you for your time,
Sincerely,
Mike Schmeltzer

Answer
If the steroid shot helped, then it is probably an allergy.  The shots do not last very long so ask your vet for tablets to keep some steroid in the body to keep the itching under control.  Of course it may be some type of skin disease other than allergy,like mange mites, so have the vet check the dog again and look for other causes of the skin itching.