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Dog Food Allergies vs Intolerance: Myths & Misconceptions Explained

Written by: Elizabeth Anderson Lopez

Last Updated on March 6, 2024 by Dogster Team

is chocolate bad for dogs

Dog Food Allergies vs Intolerance: Myths & Misconceptions Explained

Man’s best friend has a reputation for being kind and accepting of everyone. But perhaps not everything. When it comes to food, dogs can be as intolerant as that narrow-minded uncle you dread spending Thanksgiving with. But with dogs it’s different. Sometimes a food intolerance can be an actual food allergy. But how to tell the difference? And does it matter?

“Both conditions can fall under a broad umbrella called ‘adverse food response’ or ‘adverse food reactions,’” says Camille Torres, DVM, DABVP-Canine/Feline, assistant professor of community practice and Purina Nutrition Program trainee with Colorado State University. “An event that stimulates an immunologic response is more likely to be considered a food allergy whereas a non-immunologic response is more likely to be considered a food sensitivity. Signs can be very similar in that both can lead to GI signs (gastrointestinal adverse food response); however an immunologic response may also lead to itchy skin, ears and paws (cutaneous adverse food response).”

Photography ©kozorog | Getty Images

Other veterinarians share some additional distinctions:

Allergies: “An allergy is a reaction (involving the immune system) to something in food, usually a protein,” according to Megan McGlinn, VMD, medical director of the ASPCA Animal Hospital in New York, New York.

“A food allergy causes an immune system reaction when the food is eaten, which can be severe or life-threatening, including anaphylaxis,” adds Judy Morgan DVM, CVA, CVCP, CVFT, of Naturally Healthy Pets, who is certified in food therapy, acupuncture and chiropractic care for dogs, cats and horses, based in Woodstown, New Jersey. “There is a histamine release that causes swelling, fluid build-up (edema), redness and may cause shortness of breath. Digestive symptoms may also occur, including vomiting and diarrhea. Itching and secondary yeast and bacterial skin infections can also occur.”

Food intolerance: “Intolerance is not a true allergic reaction and may show up with more digestive symptoms such as vomiting, diarrhea, abdominal pain, bloating, belching and flatulence,” Dr. Morgan says. “Intolerance is generally caused by an inability to digest something well due to lack of appropriate enzymes or inflammatory bowel disease. Sensitivity to food additives such as dyes or preservatives can also cause food intolerance. In humans, lactose and gluten intolerance are the most commonly identified. Most dogs have lactose intolerance — fermented milk products work better because fermentation has broken down or digested the lactose.”

Myths and misconceptions

Along with using some terms incorrectly, many owners often believe things about food issues that are inaccurate. For starters, kibble may seem boring, but it is anything but basic. “Most of our pets are eating quite complex diets,” says Cailin Heinze, VMD, MS, DACVN, board-certified veterinary nutritionist, adjunct associate professor at Cummings School of Veterinary Medicine at Tufts University, based outside of Worcester, Massachusetts.

“The biggest myth/misconception is that a patient with food allergy or food intolerance will experience GI distress with vomiting and diarrhea when many times there are a variety of signs, with itching being the most common, especially for food allergy,” Dr. McGlinn reports.

What’s also common is the myth of grain allergies, which Dr. Torres specifically say are “uncommon.”

And grains aren’t the only ingredients that get unfairly blamed. “I have pet owners tell me their dog is allergic to all proteins and cannot eat any meats. That is genetically and physically almost impossible,” says Dr. Morgan, who Pet Age magazine named the 2018 Woman of the Year in the Pet Industry and the 2019 Pet Age Woman of Influence.  “Dogs are meant to eat meat proteins. Most dogs have a food intolerance and not a true allergy.”

That said, there are proteins that some dogs are allergic to. “It is the proteins in foods like beef, dairy and eggs that are amongst the most common food allergens, while foods that spark sensitivity can be amongst a broad spectrum and variable according to the particular patient,” Dr. McGlinn explains.

“Interestingly, most dermatologists commonly incriminate beef, but I find chicken to be a much bigger problem,” Dr. Morgan says. “Wheat, corn and soy can also cause problems for a lot of dogs.”

There is a possible cause-effect for people, even experts, believing certain proteins are to blame. “The most common allergens or animal products also reflect the diets that have been on the market at the time the studies were conducted,” says Dr. Heinze, who is also chief academic officer of the Mark Morris Institute and co-founder of Petfoodology. “So chicken, beef and eggs are very common in pet foods. There’s nothing inherent in those foods that causes allergies; it’s that there is such common exposure. I wouldn’t be surprised if five years from now you were to see pets allergic to the more unusual proteins.”

Then again, the proteins may not be the actual trigger. “Sometimes owners feed a processed food that includes a lot of ingredients, and the owner states the dog cannot eat whatever the main protein is in that food if the dog has digestive issues,” Dr. Morgan says. “In reality, it could be any ingredient in the bag, box or can and may very well be an intolerance to an additive, dye, preservative or minor player in the ingredient list.”

Dr. Heinze confirms cross contamination during processing may be the true source of the problem; you may have seen that warning on the package label on many food items for people.

So how to determine if your dog has actual allergies?

“Blood testing or skin prick allergy testing can be performed, but they are not 100% accurate,” Dr. Morgan says.

“An elimination diet can be used to identify adverse food reactions, but many times the underlying cause, whether it be food allergy or food intolerance, remains unknown,” Dr. McGlinn says. “Differentiating amongst the two will not only depend on results of the elimination diet, which takes compliance on the owner’s part, but also on patient history, time of onset to clinical signs, patient presentation and response to treatment.

In the meantime, Dr. Morgan says, “If there is a true allergic reaction including swelling of the face or ears, hives anywhere on the body, avoid that food! (This is actually not that common.)”

“People tend to jump on food issues first, but it’s actually one  of the less common causes,” Dr. Heinze agrees. “A lot of owners over diagnose food allergies, which means they eliminate foods they don’t need to.” And keep in mind that addressing those food issues might not be the only solution. “An immunologic adverse food response may require additional medications; diet alone may not control all of the signs,” Dr. Torres says.

Specific treatments, along with avoidance, include steroids and other immunosuppressants such as cyclosporine, says Dr. Morgan, adding, “Determining the cause and avoiding it is a much better solution than chronic administration of immunosuppressants. Adding digestive enzymes can help quite a bit for food intolerances to help with digestion of the food.”

Dr. McGlinn confirms finding a diet the allergic or food-sensitive patient can tolerate that will help stop clinical signs is key. “In addition, for food allergies there are a variety of medications such as antibiotics, antihistamines, antifungals, topical creams, ointments, sprays and shampoos that may also help treat the allergy and/or secondary infections and improve the patient’s overall health.”

And ultimately, it’s your dog’s health and well-being that can be affected. Dr. Morgan says with true allergies, “There is the risk of anaphylaxis and death (an overwhelming allergic reaction). Luckily, this is not that common.”

Dr. Heinze sums it up with, “These issues are not life-threatening but quality- of-life-threatening.”

They definitely cause for intervention. “Inflammation in the intestines can cause abdominal discomfort, vomiting and diarrhea; signs may worsen over time,” Dr. Torres warns. “Skin inflammation can lead to secondary bacterial and yeast infections that can be uncomfortable for the dog.”

When it comes to foods causing issues for your dog, it’s worth finding out if it’s an allergy or intolerance. Either way, there are solutions that can help your furry friend feel better. At least until Thanksgiving — and that decidedly un-woke uncle — come around.

Photography ©cmannphoto | Getty Images

Specific Breeds and Allergies

Food intolerances and allergies affect a variety of breeds, purebred as well as mixed breed dogs, says Camille Torres, DVM, DABVP-Canine/Feline. Others cited certain breeds as being more common patients.

“Top breeds associated with food allergies include Labrador Retrievers, Cocker Spaniels, Soft Coated Wheaten Terriers, Dalmatians, West Highland White Terriers, Bichon Frises, Collies, Chinese Shar-Peis, Lhasa Apsos, Dachshunds, Miniature Schnauzers, Boxers and Springer Spaniels,” says Megan McGlinn, VMD.

Age can be a factor, too. “Age at presentation is typically less than one year. A diagnosis of food allergy should be at the top of the list in a puppy or dog that has an onset of pruritus (itching) or other clinical signs prior to 6 months and after 6 years of age.” McGlinn adds that food intolerance has been seen in a wide variety of breeds at any age.

Cailin Heinze, VMD, MS, DACVN, board-certified veterinary nutritionist, adds Labs and Goldens tend to have more allergies “and there tends to be a genetic trait. Allergies can run in families. They may not be allergic to the same things but they inherit those immune systems.”

Finally, Judy Morgan DVM, CVA, CVCP, CVFT cites White American Bulldogs, English Bulldogs and all French Bulldogs as being allergy-prone breeds, as well.

Learn more about dog health care at

About the author: Elizabeth Anderson Lopez is an award-winning writer based in Lake Forest, California. She and her husband have many pets, including two English Bull Terrier rescues named Dexter and Maybelene. You can contact her at

Featured Image Credit: rfranca/ Getty Images

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