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Food Allergies in Dogs

By Colleen Williams and medically reviewed by Sarah Wallace DVM
January 6, 2019 • 3 min. read
dog next to food bowl

With all the mysterious ingredients in pet foods nowadays, allergic reactions and intolerances are very common. Intolerances to food are different than food allergies; with intolerance, the ingredient may not agree with the animal’s digestive system but doesn’t invoke an immune response. Additives like wheat, corn, coloring, and dairy products aren’t what you’d normally consider to be dog food, but they’re often added to your pet’s food. While the symptoms can be similar, here’s how the two conditions are very different.

Common Food Allergens

Just like environmental allergies, food allergies are caused by antibodies in the dog’s intestines overreacting to a particular allergen, leading to a histamine response. This reaction is what causes the visible symptoms. The allergic reaction is caused by a protein source in the food. It is possible for dogs to be allergic to the protein part of lactose, wheat, and soy, just like humans. Food allergies and intolerances aren’t influenced by gender, breed, size, or even age; dogs can develop them at any point in their lives.

A particular ingredient in their food causes an immune reaction. The following are the most common problem foods, in order:

  • Beef
  • Chicken
  • Dairy
  • Chicken eggs
  • Fish (cats)

These are the most commonly found ingredients in pet foods, and therefore pets have been continuously exposed throughout their lives.

Much less commonly, dogs can develop a food allergy to vegetables and carbohydrates as well – these ingredients have less protein than animal meat, and that makes them less likely to cause an allergic reaction. Grain allergies are rare, and gluten allergies are even rarer – only having been documented in Irish Setters, possibly in Border Terriers, and have never been seen in cats.

Signs Your Dog Is Allergic to a Food

Allergies and intolerances have many of the same symptoms but very different internal responses.

Food Intolerances:

  • Diarrhea
  • Weight loss
  • Vomiting
  • Abdominal pain
  • Excessive flatulence
  • Anorexia (lack of appetite) due to food intolerance occurs because of the inability to digest the food

Food Allergies

Caused by the immune system, allergic reactions cause:

  • Low appetite
  • Burping
  • Vomiting
  • Diarrhea
  • Excessive flatulence
  • Itchy skin

Skin conditions are a large part of food allergies; histamines can make your pet’s skin miserably itchy to live in. Dogs will scratch, bite, rub and roll to try to satisfy the itch. Dogs can itch themselves to the point of causing wounds or sores and can develop secondary skin infections from bacteria and yeast.

If your pet is scratching themselves more than a few times per day or is showing any of the other signs of food allergy or intolerance, you should bring them to your veterinarian right away to figure out the cause and how to make them more comfortable.

Treatment for Your Dog’s Food Allergies

The vet will perform a physical exam, as well as blood and urine tests, to rule out any underlying diseases. They will also need a thorough history of the symptoms and any changes in your dog’s diet in order to diagnose your pet. Dogs with extreme vomiting and diarrhea may need hospitalization to replenish fluids, and antibiotics may be given if your pet has open wounds with the potential for infection.

A food elimination diet, also called a “diet trial,” for 8-12 weeks is the only effective way to diagnose food allergies and intolerances. Your vet will choose a novel food that your dog has not had access to before. It’s extremely important to stick to only this food – no treats or table scraps – otherwise you are wasting your time. The purpose of the elimination diet is to see if your pet improves when they are not eating their previous food.

Saliva or blood food allergy tests are unreliable and are inaccurate ways to assess food allergies or intolerances. Save your money and put it towards the diet trial food.

Managing Food Allergies

If the elimination diet is successful, stick to a veterinarian-recommended food that doesn’t contain the trigger. Make sure you carefully read the ingredients on treats, vitamins, chewable toys, and medications, checking that they are free from the allergenic food. Inform all family members of the new diet to ensure there are no slip-ups. Don’t feed your dog table scraps or human snacks, just in case.

Food allergies and intolerances are very common among dogs; they account for roughly 20% of all excessive scratching. See a veterinarian if your dog’s itching becomes so severe that it causes bleeding, rawness, or baldness. Any diarrhea or vomiting warrants a veterinary appointment as well, as these can be symptoms of other diseases. If your veterinarian recommends a specific diet, it’s extremely important to stick to it; allergies are often progressive, and symptoms can worsen with each feeding of the allergen.

The content is not intended to be a substitute for professional veterinarian advice, diagnosis, or treatment. Always seek the advice of your veterinarian or other qualified health provider with any questions you may have regarding a medical diagnosis, condition, or treatment options.

Want to know more about conditions that can affect your dog? Check out the Healthy Paws Cost of Pet Health Care report.

colleen williams
By Colleen Williams

Over the past decade, Colleen has written about health, wellness, beauty, and even pets for The New York Times, The Cut, Refinery29, xoVain, Healthy Paws Pet Insurance, and Seattle Met Magazine, as well as many beauty brands. She has a BFA in Art History from the University of New Mexico and an AAS in Fashion Design from Parsons School of Design in New York.

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Sarah Wallace DVM profile photo
By Sarah Wallace DVM

Dr. Sarah Wallace is the vice president of telehealth at Galaxy Vets, based in Fort Collins, Colo. She is actively working to increase access to veterinary care, to develop more effective communication strategies to bridge the gap between veterinarian knowledge and pet parent understanding and build happy and sustainable veterinary teams. Dr. Wallace studied biology at Lafayette College in Pennsylvania and attended veterinary school at Western University of Health Sciences in California. After graduation, Dr. Wallace started working with Just Food for Dogs, an innovative pet food startup out of southern California advocating fresh, whole-food diets for dogs. She also completed a small animal rotating internship at San Francisco Veterinary Specialists - receiving one-on-one training with San Francisco's top veterinarians in internal medicine, neurology, dermatology, oncology and surgery. After working in clinical practice, Dr. Wallace joined the field of telehealth. Dr. Wallace writes and reviews blog content for Healthy Paws Pet Insurance. Dr. Sarah Wallace on LinkedIn Cardinal Veterinary Works Consulting

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