My poor yorkipoo is balding on one side. What could be causing this?

[shawn]

You already know that your dog has allergies, so that could be what is going on once again. Also, at her age and being a little overweight, she could have a thyroid problem. This can cause skin issues in dogs. It wouldn't be a bad idea to have a thyroid test done on her.

Alopecia just means hair loss, so don't get concerned over people here who are tellling you it could be that. If she's losing her hair of course it is!

Your dog's allergies could be seasonal, from something she's inhaling -- could be food --- could be contact allergy, or could be a combination of those.

I would find an experience vet with a compassionate staff. He/she will give your dog something to control the itching (we use temaril p or medrol most of the time) and if the skin is actually infected, antibiotics such as cephalexin will be used for possibly even 30 days. Your vet can perform a skin cytology to diagnose the issue regarding infection. Some vets will just do this by sight.

Our docs recommend Science Diet Sensitive Skin food first. If that doesn't help, they can move into prescription diets, such as d/d or z/d ultra (see the Hills Science Diet Website.) Adding omega 3 fatty acid supplement couldn't hurt anything, and may help.

Beware of medicated shampoos. Some actually rough up the layers of the skin, inviting infection. A good oatmeal shampoo without perfumes, etc, (for dogs) would be a good choice. You have to make sure your dog is thoroughly dried.

For inhalent allergies, you just manage them with whatever meds work -- trying to avoid heavy steroid use. Benedryl works sometimes, but not often. The meds I mentioned earlier DO work.

There is allergy testing for dogs. A blood sample is sent to the lab, and the results will give you all the sensitivities found. Some people will give allergy injections to their dogs. I believe they work in about 1/3 of the cases.
Food allergies are not diagnosed with blood testing. The solution there is to go with a food, such as z/d ultra, which the body cannot recognize and react to. Your dog is small, so it wouldn't be too terribly expensive to just keep her on it, provided your vet agrees. The food is made in a sterile environment -- nothing like foods being sold anywhere else.

SO your dog may have allergy to fleas, to foods, to something in the air, or something she's touching. Allergies cannot be cured, but managed. You need to find a good vet who'll work with you. Ours will allow refills without exams after they are sure their recommendations are being followed faithfully. Flea and food allergies are easiest to deal with.

I hope this helps you. I have been a vet tech and have owned a lab that was allergic to most everything.