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Q&A: Why Are My Dog's Hot Spots Causing Hair Loss?

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Dr. Mark is a veterinarian. He has been working with dogs for more than 40 years.

There are many possible reasons for hair loss in dogs.

There are many possible reasons for hair loss in dogs.

Are My Dog's Hot Spots Causing Her to Lose Hair?

"I have a Great Pyrenees, and I believe she has hot spots but it has spread all the way across her back and she has lost almost all her hair. It’s very thin and steadily coming out. I used a spray that the vet recommended, and it made the spots worse (certain spots had more pus and bled). The shampoo I have seems to help a lot. But I’m not sure what is making it spread across her back and causing her to lose her hair the way it is. She’s an outside dog.

This has been going on for weeks now. Any suggestions on what to do?" —Desiree

Possible Reasons Your Dog Is Losing Hair

Hot spots are a simple problem to take care of at home if done correctly. In your dog's case, however, there is probably an underlying issue that needs to be taken care of.

Allergic Reaction to Fleas

My first concern when you described the hair loss with the hot spots would be fleas. Is your dog on an effective flea control medication? Allergic dogs can react with hair loss and hot spots after only a single flea bite. If you do not see any fleas on your dog, you can check her back at the base of the tail and see if there are any black flakes left by a flea.

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Read More From Pethelpful

Summer Allergies

Summer allergies are also a possibility, and by now she may have pyoderma, a deeper skin infection.


If the hair loss is going on with no itching, I would also worry about hypothyroidism. Here are some other causes of hair loss in dogs.

Visit Your Vet

You will need to take her to your vet for a blood test for hypothyroidism, and during that exam, they can see if it is just hot spots or a generalized bacterial infection, pyoderma. She might need to be on an antibacterial medicated shampoo.

Please stop using the spray until you have had a chance to have her skin examined. They can also give her a medication to stop the hot spots or pyoderma from getting worse in the short term, and she will feel better.

This article is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from your veterinarian. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.

© 2022 Dr Mark

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