My eight-month-old female English Mastiff has spots of
hair loss on several places on her body. Our vet
tested her for mites. She doesn’t have any.
Tested her thyroid, it’s normal. He thinks it
might be a food allergy to chicken and corn, so he
changed her food from [a major commercial brand
to a hypoallergenic formula]. I add a little
canned food to her dry food and also use the
canned food to make her treats. She doesn’t
scratch herself excessively. Do you think we’re
on the right track to resolve this problem? I
would appreciate any advice you can give us.
Based on your description of the spots (multiple spots, not itchy or inflamed), my first guess would have been puppy mange (also known as demodectic mange) is to blame. I wrote a somewhat extensive article on the topic a while back. You can read it by clicking here.
The test for puppy mange (called skin scraping) is pretty reliable. Nonetheless, in rare instances the test does fail to detect the mites involved in the syndrome. So one thing I recommend is that you keep puppy mange in the back of your mind as a possibility.
Certainly allergies (to food, pollen, fleas, or other environmental stimuli) can cause hair loss. But they usually cause itching and red skin as well. Thyroid problems can cause hair loss, but they are extremely rare in young dogs.
In my opinion, you have a couple of choices. The most aggressive tactic would be to perform biopsies of the affected areas. Samples of affected skin can be removed and sent to a laboratory for analysis. Biopsies are highly likely to lead to a diagnosis.
However, I’m not sure it’s necessary to go that far. If the bald spots are small and aren’t causing any irritation, it may be reasonable to take a wait-and-see approach.
Consider your dog’s age. An eight-month-old Mastiff is roughly equivalent to a 13-year-old person. Many 13-year-olds have acne. The blemishes associated with acne occur because the immune system is not fully matured. At this age, the immune system has a habit of over-reacting to some problems and under-reacting to others. The result is acne.
Your dog does not have acne per se. However, there is a very good chance that her patchy baldness is related to her immature immune system. If you wait a few months, the problem may resolve as her immune system matures.