Why is my puppy losing hair on his hindquarters? Food or fleas?
Updated On September 23rd, 2025
Pet's info: Dog | Mixed Breed Large (61lb +) | Male | unneutered | 7 months and 2 days old | 45 lbs
My 6 month old shepherd-lab mix is losing hair in his hindquarters. It's happened before after we switched food, but grew back when we switched back. His worm medicine was late this month, but he had it about a week ago and the hair loss is getting worse. I'm not sure of the name of the med (I'm at work right now), but it's a brown chewable that looks like a treat, and the vet said it would treat/prevent fleas, heartworm, roundworm, ringworm, and ticks.
2 Answers
Most Helpful Answer
Published on December 6th, 2016
From the description provided, your pet may be suffering from allergies secondary to fleas, environmental allergens such as dust, pollen, grass, or even a protein source in his diet. In addition to the food trial, it is imperative to administer the flea prevention on time every month. Even one flea bite can set off a reaction that can ultimately lead to a secondary skin infection.
1Pet Parents found this answer helpful
Related Answers from Veterinarians
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Published on November 25th, 2018
Thanks for using Petco Pet Education Center, formerly Petcoach! This is possibly due to allergies. It really comes down to figuring out what is causing him allergies so that they can be treated or the specific allergen avoided. A secondary infection is likely and also needs to be addressed. There are many things that can cause allergies though in most cases they can be broken down into 3 big categories: flea, food and environmental allergies. Allergies are usually worked up in a stepwise fashion starting with flea allergies as this is the easiest and cheapest to take care of. If not on a flea preventative, then it would be a good idea to get started on one. If already on one then it would be a good idea to change to something else (there are many new products out in the market). If not improved in 1-3 months then it is time to move on and check for food allergies by switching to a novel diet (new protein and new carbohydrate). If that does not seem to be the issue then you are left out having to check for environmental allergies which require blood and/or skin tests. Allergies can be very frustrating to deal with at first but so rewarding at the end when we are able to treat them effectively!
1Pet Parents found this answer helpful
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