Get the Facts on Food Sensitivities in Dogs


Editor’s note: Have you seen the new Dogster print magazine in stores? Or in the waiting room of your vet’s office? This article appeared in our April/May issue. Subscribe to Dogster and get the bimonthly magazine delivered to your home.

I recently received an email asking if I could recommend a commercial dog food containing alligator as the protein. The sender explained that she was desperate because her dog showed signs of food sensitivity to every other protein.

The email got me thinking. How did we, as a global community of canine caretakers, create a scenario whereby modern dogs have become intolerant to so many foods that they must resort to consuming alligator — an extremely unnatural protein source for their predatory heritage? And what can we do to prevent food sensitivities from occurring in our own dogs?

Alligator by Shutterstock.
Alligator by Shutterstock.

For answers, I turned to W. Jean Dodds, D.V.M., founder of Garden Grove, California-based Hemopet animal blood bank and Hemolife testing lab. Dr. Dodds is the creator of NutriScan, the first saliva-based food intolerance test for dogs, cats, and horses. In the following Q&A, Dodds unravels the mystery surrounding canine food intolerances and how we can protect our own dogs.

Dogster: What are food sensitivities in dogs?

W. Jean Dodds: Food sensitivities, also called food intolerances, are an immune system response to ingredients the body views as harmful. When a dog ingests a problematic ingredient, called a food antigen, the immune system produces the antibodies IgA and IgM to attack and destroy the “invader.” Because every dog is an individual, foods that trigger sensitivities in one dog will not necessarily do so for another. Food sensitivities are chronic reactions that typically build up after repeated exposure to the offending food antigen(s) and usually take months, or even years, before outward signs appear.

What are the most common clinical signs of food sensitivities in dogs?

The hallmark of food sensitivity is itching (or pruritus, in medical terms). Food sensitivities also typically manifest as gastrointestinal and skin issues. Gastrointestinal signs often mimic irritable bowel syndrome, such as chronic diarrhea or loose stool, gas, and stomach rumbling. Skin problems include unexplained itchiness and infections, especially of the ears and feet, often accompanied by yeast. If the offending food is not eliminated, chronic inflammation resulting from the sensitivity might lead to more serious illnesses, such as autoimmune diseases or even cancers.

Itchy dog by Shutterstock.
Itchy dog by Shutterstock.

What is the difference between food sensitivities/intolerances and food allergies?

Food allergies involve a different type of immunologic response. When the body is exposed to a food allergen, it produces the antibody IgE to attack the offending ingredient. Reactions to a true food allergen typically occur immediately or shortly after the ingredient is ingested, and symptoms are often severe, such as hives, a swollen face, or even anaphylaxis, with a closure of the airways. True food allergies are rare in dogs, and most cases of diagnosed food allergies are actually food sensitivities/ intolerances.

Why do so many dogs suffer from food sensitivities/intolerances?

A major contributing factor might be the constant exposure to just one or two proteins in the diet … many companion dogs consume one food every day for years, resulting in repeated, longterm exposure to one protein and one carbohydrate. Further, these kibbled foods undergo much processing during cooking and extrusion, so the ingredients are frequently oxidized and denatured. Over time, the protein and carbohydrate burden the dog’s immune system, triggering sensitivity. Some dogs might also lack specific chemicals or enzymes needed to digest certain ingredients, and others might have an impaired ability to absorb particular food compounds.

How can you decrease a dog’s likelihood of suffering from food sensitivities/intolerances?

Rotating among three or four different types of proteins every few months will give your dog’s body a “vacation” from each source, helping to avoid a sensitivity from forming. If you feed kibble, consider alternating between three or four limited-ingredient formulas, with just one protein and carbohydrate source in each formula. Avoid exposing a healthy dog to “novel” or exotic proteins, such as kangaroo, ostrich, and alligator. You want to save these ingredients for use in the event the dog develops food sensitivities later in life.

It’s not uncommon for a dog to refuse to eat a particular food but have an otherwise robust appetite. Could this indicate a food sensitivity/intolerance to an objectionable ingredient?

It’s certainly possible. Studies among numerous species of animals, including humans, show that we form an instinctive repulsion to the taste of foods that we associate with feelings of illness, such as nausea or vomiting. This is referred to as “learned taste aversion,” and it originated as a survival mechanism to protect wild animals and primitive human beings from consuming rancid or poisonous foods. If a wild animal became ill from ingesting a poisonous berry, learned taste aversion could prevent further consumption of the same berries, thus avoiding more severe illness or death. If a dog with an otherwise normal appetite refuses to eat one or two specific foods, she might be telling you that the foods disagree with her. For that reason, I never recommend forcing a dog to eat a food she resists.

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