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Donna P.
Donna P., Veterinary Technician
Category: Dog
Satisfied Customers: 1234
Experience:  Veterinary Technician with 15 years experience. Boston Terrier Breeder
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Why is my dog biting his backside and losing fur

Customer Question

We came back off of a trip and our XXXXX XXXXX/chihuahua had gotten fleas. We treated with Hartz Advanced care flea\tick drops and he got a bath as soon as we returned home. The fleas seem to be gone, but now he is biting on his right rear side and scratching hard enough to draw blood. He's losing fur there, too, and is constantly licking and smelling his paws. It looks like he's starting to do the same thing on the other side, too, and under his fur, there are a few red bumps on the left side. Is there anything I can do and what is causing it? Thank you for taking the time to answer my question.
Submitted: 8 years ago.
Category: Dog
Expert:  Donna P. replied 8 years ago.


From the areas that you are describing him itching, I would suspect that fleas are still the culprit. It is possible that it is only the reaction from past bites that can continue to bother the dog for several weeks. It is also possible that there are still some fleas left that are hard for you to detect but are enough to bother a dog with flea allergies. I always recommend frontline for dogs with flea allergies as it can kill the fleas before they have a chance to bite -whereas most other products require the flea to bite to get a dose of the drug. Since it is the bite they are allergic to - the frontline seems to work better with these dogs. It can still take a few weeks for the reaction to be totally gone.

If he is developing "hot spots" from chewing and licking so badly that he is drawing blood - he may need to go to the vet if you start to notice any signs of infection in the area. Watch closely for any discharge that looks like pus. Hotspots can start from virtually anything - bug bites or other irritations. The dog then just keeps making the problem worse with the chewing. Treatment of the hot spots usually revolves around keeping the area clean and dry and preventing the dog from continually licking and causing further damage. There are several shampoos that you can buy specifically designed for hot spots. They often have calming agents like oatmeal and can be medicated with lidocaine type compounds to keep them from being so irritated. There are also some shampoos that have benzoyl peroxide in them if you are noticing little pustules. Many of them have to sit on the dog for a specific amount of time so read the bottle carefully. Washing with just diluted antibacterial handsoap, rinsing, and keeping the fur in that area trimmed short can help a lot. Some people have had some luck with astringent skin cleansers - like for your face. This can definitely help to dry the area if it is oozing - but it can be very irritating if the area is highly irritated. There are also topical sprays that contain hydrocortisone that can help the spot be less itching and inflamed. Usually it is safe to give the dog benadryl for systemic help with the allergic reaction. The normal dose is 1 mg per pound twice daily. This usually takes a day or two of continued use to notice a difference. (I always recommend checking with a vet before giving your dog any medications or treatments)

If you haven't noticed significant improvement in several weeks or if the condition continues to worsen - it is probably that your dog is allergic to something else. This can range from anything from inhaled pollens to foods. It may be worth bringing him to the vet for allergy testing so that there can be more targeted treatment. The vet can also prescribe steriods to help with the itching and inflammation if things worsen.

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Donna P.

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