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Why is my dog shedding and itching? Could it be sudden food allergies?

Updated On September 23rd, 2025

Pet's info: Dog | Mixed Breed Medium (23 - 60lb) | Male | neutered | 1 year and 1 month old | 49 lbs

My dog is shedding a lot and itching a little. I got him skin application medicine for fleas and he was dewormed earlier than 3 months. He has been eating almost the same food since he was 2 months old. I have only switched to adult dog food from puppy food. Can food allergies in dogs start suddenly?

2 Answers

Most Helpful Answer

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Answered By Dr. Melanie, BVSc MS

Veterinarian

Published on March 20th, 2018

I'm sorry Cooper is having trouble with itching! I'm not sure how long ago you placed the flea medication on him, but if he wasn't up to date on it before, it still could be a problem with the fleas causing his symptoms. Should he have had a heavy burden of fleas, he could have developed a flea allergy causing this shedding and itching. In addition, when a dog has fleas, the environment needs to be disinfected as well to get rid of all the fleas. Allergies can develop suddenly in dogs, and while a food allergy may be possible, it's not a very common type of allergy in dogs. The majority of dogs with allergies have an environmental allergy, so that could also be a possible cause of his shedding and itching. I recommend taking Cooper into a vet today for an exam. The vet can diagnose what is causing his symptoms, and can treat him for it. Good luck!

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    Answered By Ricardo Fernandez, DVM

    Veterinarian, Veterinary Oncology Resident

    Published on August 23rd, 2017

    Hi there! Thanks for using Petco Pet Education Center, formerly Petcoach! This is common with flea allergy dermatitis. It is great that you have done what needed to control the fleas. However, it sounds like Cooper is still having the clinical signs of itchiness and allergy. The reason is that even if you do not see any fleas, they could still present in small amounts. It only takes 1 flea to cause allergy signs. The other thing to consider is that usually secondary bacterial infections which happen secondary to the flea allergy can cause a great amount of itch and they need to be treated appropriately along with the fleas. I advice that you have him evaluated by your veterinarian to start therapy for the likely secondary infection and further therapy for fleas if needed based on examination. Good luck!

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