10 Food Allergy Myths for Dogs and Cats

The internet is full of information about food allergies in dogs and cats. Unfortunately, much of it is wildly inaccurate!

Let’s debunk 10 of the most common food allergy and testing myths:

1. Grain-free Diets Are Hypoallergenic. This is one of the biggest misconceptions about allergies in dogs and cats. Although a very small percentage of dogs are allergic to the protein component of grains, the main trigger of most food allergy cases is the protein source of the diet (chicken, beef, dairy, soy, fish, etc.).
2. Dogs Can’t Be Allergic to Foods They’ve Eaten Their Entire Lives. Food allergies require a sensitization period (aka exposure) to a protein source in order to develop an allergy. Therefore, food allergies are always to a protein that a pet has already eaten in their diet, whether it has been consistently or intermittently. A full diet history is important when working up a suspected food allergy and picking a test diet.
3. Pets without Gastrointestinal Symptoms Don’t Have a Food Allergy. Skin inflammation and infections are much more common signs of a cutaneous adverse food reaction than vomiting or abnormal stools. In fact, only 10-15% of dogs with a true food allergy will have gastrointestinal signs. Many animals with gastrointestinal symptoms have a food intolerance (meaning they cannot digest a protein, similar to lactose intolerance in humans), which is immunologically different from a food allergy. Food intolerances will not have associated skin signs.
4. Hypoallergenic Diets Are Not “Real” Food. There are two types of prescription-based hypoallergenic diets used to diagnose food allergies. Novel protein diets are made of unique proteins, like kangaroo or rabbit. In order to be successful with a novel protein diet, a pet cannot have been previously exposed to the protein source, which means that a full diet history is required. Hydrolyzed diets are made of real protein bases (chicken or soy), but the protein is broken down during manufacturing to a smaller size, which doesn’t trigger the immune reaction. Both are nutritionally-balanced diets and are real food!
5. Over-the-Counter, Limited-Ingredient Diets Are Sufficient for Diet Trials. Over-the-counter diets are not held to the purity standards of prescription diets. This means that there can be accidental cross contamination of proteins from the manufacturing process, meaning there are small amounts of proteins mixed in that are not listed on the label. Since diet trials require strict diet management/restriction for at least 6 – 8 weeks, it is important to use a diet that is guaranteed to contain only a single or hydrolyzed protein.
6. Blood or Saliva Tests Are Just as Good at Diagnosing Food Allergies as a Diet Trial. Although diet trials are much more restrictive and challenging, they are the gold standard and only accurate testing available to animals. Blood panels are often used in human medicine, but they are very inconsistent in animals. Even though both types of tests are commercially available, studies have shown that the results of the blood and saliva testing are unreliable and often inaccurate. Unfortunately, there is no easy way to diagnose food allergies in dogs and cats.
7. A Few Little Cheats Won’t Affect a Diet Trial’s Outcome. One of the most common hiccups in diet trials is not eliminating all other protein sources from the diet. This includes flavored supplements, chewable medications with flavoring (flea/tick preventatives, heartworm prevention, etc.), rawhides, other animal product chew toys (antlers, pig ears, etc.), and human treats. It can take several weeks for allergenic proteins to clear the system, so any re-introduction during the testing period will affect the ability to confirm or exclude a diagnosis of a food allergy. It is important to have all family members on board with the rules of diet trials.
8. Home Cooked or Raw Diets are Better for Allergic Dogs. Although there are a small number of pets that are allergic to non-protein allergens in commercial pet foods, the majority of dogs and cats are allergic to the main protein in any form (cooked or uncooked). Even though home cooking is a gold standard for dieting, protein selection is still the most important factor. For example, if a pet is allergic to chicken in a kibble, they will still react to a home-cooked chicken breast. When a home-cooked diet trial is pursued, consultation with a nutritionist to formulate a novel, protein-balanced diet is recommended.
9. Pets Won’t Eat a Hypoallergenic Diet. While it is challenging for many owners and pets to eliminate all the extras and feed a single diet for months, most pets will adjust. If they are not readily eating the diet, your veterinarian may be able to offer alternative diets or tips for getting animals to adjust to new foods. Dogs and cats are much more tolerant of eating the same thing over and over than we give them credit for. Although our pets love treats and extra snacks, it is often more challenging for the owner to give them up during diet trials.
10. Prescription Diets Are Expensive and Permanent. Food allergies are confirmed by resolution of clinical signs (skin and gastrointestinal) while on a strict diet trial. If your pet is diagnosed during a food trial, there are several options for moving forward. Many owners are very happy with the diet from the trial period and elect to keep their pet on it long term. These diets are generally well balanced and acceptable for long-term maintenance. Other owners will pursue individual ingredient challenges in which they systematically add in home-cooked proteins one at a time to see if their pet reacts. After the individual challenges are completed, an owner will have a list of proteins that a pet can tolerate and they can begin transitioning back to over-the-counter diets.

Diet trials can be very challenging, but they are an extremely important step in the allergic workup for dogs and cats. Although food allergies are harder to diagnose, they’re actually much easier to manage long term than environmental allergies. If you are concerned about a possible food allergy, it is very important to speak to your veterinarian to help with selection of test diets and duration of diet trials. Also, it is important to discuss how to successfully transition to the new test diet to ensure that there is no gastrointestinal upset.