Hello. Thank you for asking your question on just answer. My name isXXXXX will try to help.

If it just happens spring through fall, then Tank has seasonal allergies also know as "atopy" or "atopic dermatitis."

If you want to know what he is allergic to, then your vet can pull blood and send it off to a lab for allergy testing. Once you know what he is allergic to, he can be given allergy shots just like people get. This would desensitize him to the allergens.

It is important to bathe him twice a week to wash the allergens off him. Use a gentle oatmeal shampoo. Some of the medicated shampoos are too harsh and cause skin problems.

An air cleaner, or air purifier, may help with the allergies as well.

Wash his bed, and toys, once a weeks to remove the pollen and allergens.

You can give him an antihistamine through his allergy season.

Start with benadryl, the dose is 1 mg per pound every 12 hours. For example, a 100 pound dog would get 100 mg of benadryl every 12 hours.

You can try other antihistamines as well.

You can add a tablespoon of fish oil to the food once a day. The fish oil contains omega-3 fatty acids which help with allergies and skin inflammation.

If he has itchy spots, you can apply hydrocortisone cream, or spray, three times a day.

Make sure you use a high quality flea control as well. The fleas come out more in the spring. If he is allergic to flea saliva, then he will have a big allergic reaction with one flea bite. The most common site of hair loss, due to flea allergy, is on the back.

I hope this helps.