Food Allergies in Dogs and Cats

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Food Allergies in Dogs and Cats

If your pet is itchy, you might be wondering if they have a food allergy. While true food allergies aren’t as common in pets as one might think, it’s still possible that your dog or cat’s food is contributing to her constant scratching and licking. Keep reading to learn how pets develop food allergies and what you can do to help your itchy friend!

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How do dogs and cats develop food allergies?

Pets can develop food allergies after their immune system has been previously “exposed” to a particular food or ingredient. Food allergies can develop in puppies that are just a few months old to any stage of adulthood. Most commonly, the pet has been eating a certain food for months or years before any allergy symptoms first appear.

Common Causes of Food Allergies in Dogs and Cats:

Protein sources are one of the most common contributors to food allergies in pets. Frequent culprits include:

  • Beef
  • Chicken
  • Dairy products
  • Eggs
  • Wheat
  • Corn
  • Soy
  • Fish

Other Causes of Food Allergies in Dogs and Cats:

Possible genetic (inherited) factors can make certain breeds of dogs and cats more prone to food allergies. While any breed can develop food allergies, Cocker Spaniels, West Highland White Terriers, Labrador Retrievers, and French Bulldogs seem to be most at risk.

Symptoms of Food Allergies in Pets:


  • Itchy, dry, or crusty skin
  • Hair loss (alopecia)
  • May affect one area of the body such as the paws, or several areas such as ears, face, paws, area around the anus, armpits, groin, and more.
  • Secondary skin infections due to constant scratching and/or licking
  • Note that food allergies have skin symptoms similar to other allergies like flea and environmental/airborne allergies.


In rare cases, pets can have severe allergic reactions to certain foods. Signs include hives, swelling of the face/head, and/or problems breathing. If your pet develops any of these signs contact the nearest vet immediately.

How are food allergies diagnosed in dogs and cats?

Certain tests are needed to diagnose food allergies and determine the best treatment for your pet. Your vet will perform a thorough physical exam of your pet and gather information from you for a complete medical/dietary history. It’s important to list everything your pet eats including:

  • Food (including any new or long-term diets)
  • Treats and table scraps
  • Heartworm medication
  • Other chewable medication
  • Hairball treatment
  • Stool (if your pet eats its own poop or perhaps likes to eat cat poop)

Food elimination trials are the best way to diagnose food allergies in dogs and cats. The suspected food allergen is completely removed from your pet’s diet for about 6-12 weeks. Your vet will provide or recommend a commercially prepared, nutritionally complete diet. A second option is to prepare a home-made diet. This should only be done under strict veterinary supervision to avoid nutritional deficiencies and other health problems.

This new diet is the only food given to your pet during the trial period. Improvement of symptoms while on this food elimination trial indicates a likely food allergy diagnosis. Your vet may instruct you to “challenge” your pet by reintroducing an ingredient to see if it causes symptoms to return. If any signs return, this likely means your pet is allergic to that ingredient and should avoid eating it from now on.

If your pet refuses to eat the elimination diet, be sure to contact your vet. This is especially important for cats that refuse to eat for more than 24 hours.

Schedule follow-up appointments with your vet to monitor your pet’s progress during the food trial and be sure the let them know about any improvements or worsening of symptoms. Your vet may recommend referral to a specialist (veterinary dermatologist), especially in persistent, severe, or complicated cases.

Treating Food Allergies in Dogs and Cats

Your vet may prescribe corticosteroids or antihistamines to control itching and antibiotics or other medications for secondary infections if needed. Medicated shampoos may be prescribed to help relieve itchy, inflamed skin. While these treatments help your pet’s symptoms, determining and avoiding the cause of the food allergy is the best way to treat your pet.

Once your pet has been diagnosed with a food allergy and the ingredient(s) has been identified, avoid feeding the ingredient(s), even in small amounts. Make sure everyone in the household, pet-sitters, and boarding facilities are aware of your pet’s food allergy. If you have multiple pets you may have to feed them all the same hypoallergenic diet or feed them in separate areas (rooms/kennels).

Note that your pet may develop a food allergy to other ingredients later in life. Contact your vet if any signs or symptoms return.

Read more:

Diagnosing and Treating Environmental Allergies in Dogs

Choosing the Right Prescription Diet for Your Dog

Allergies in Dogs

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Published: 12/3/2020
Dr. Denise Michanowicz, Veterinarian

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