Food allergy is one of the five most common allergies or hypersensitivities known to affect dogs. In a pet with an allergy, the immune system overreacts and produces antibodies to substances that it would normally tolerate. This excessive response is termed an allergic or hypersensitivity reaction.
Many pets will occasionally “react” to something they ate. This represents a food intolerance, or a sensitivity to a particular type of food, causing a mild gastrointestinal upset, rather than a true allergic reaction.
In an allergic reaction to a food, antibodies are produced against some part of the food, usually a protein or complex carbohydrate. Since antibody production is required for an allergy to develop, food allergies usually manifest in adult pets after prolonged exposure to particular food ingredients.
Symptoms of a food allergy
In the dog and cat, the most common sign of a food allergy is itchy skin. In particular, itchy arm pits, ventral abdomen, ears, paws, or groin region. Pets can also manifest food allergies in recurrent ear infections, anal gland issues, or skin infections.
Some pets may also develop digestive disturbances such as vomiting or diarrhea.
How is the condition diagnosed?
The best and most accurate method of diagnosing a food allergy is to feed a novel limited ingredient diet or a hypoallergenic diet for eight to twelve weeks as an “elimination trial”.
To be a true elimination trial for your pet, this special diet must contain a novel protein and carbohydrate ingredients that the pet has never eaten in the past. This also requires that no other foods, treats, rawhides, chews or flavored supplements be fed during the trial period. Each time a pet eats food containing allergenic substances, the antibodies react with the antigens and symptoms occur.
Are some ingredients more likely to cause allergies than others?
Yes, proteins are the likely culprit in the majority of dog and cat food allergy cases.
Common Protein Sources that dogs and cats can develop allergies to include:
– Dairy including whey, milk, and cheese
– Red meats including beef and lamb
– Poultry including chicken, turkey, and duck
– Other: eggs or seafood.
Dogs can also develop allergies to carbohydrates such as corn, wheat, and soy.
Many people think that grain free pet food equals allergy free pet food, but this is not true because allergies to proteins are more common than to carbohydrates. Less than 5% of dogs and cats have a grain allergy. Additionally, pets with food allergies commonly react to multiple different ingredients, and grain free may only address part of the problem. If your pet has been on a grain free diet and the allergy symptoms have not improved, a more extensive elimination diet may still be necessary.
What foods are unlikely to cause allergies in Pets
Dogs – Rabbit, Kangaroo, Venison, Fish, Oats, Rice, Potato, Peas, Carrots, green beans, and apples
Cats – Rabbit, Duck, Pumpkin, Green Pea, Potato
What about over the counter pet diets?
When a food allergy is suspected by you or your veterinarian, a prescription diet is the most accurate way to diagnose the allergy. Over the counter diets purchased at Pet Stores are not good chooses for elimination diets. These foods are poorly regulated and do not contain certified pure ingredient sources suitable for pets with allergies.
Over the counter diets are often misleading in the ingredients they contain. When tested many over the counter diets have up to 10% contamination by weight with ingredients not on the label. These over the counter foods are also made on equipment that is contaminated with a variety of ingredients. Pet food producers often change the ingredients in their foods based on availability and cost. Legally, ingredients in over the counter diets can be changed without changing the food label for up to six months. The labels of an over the counter pet food should be thought more of as identification of the food’s flavor than the true ingredients.
If you complete an elimination diet with an over the counter pet food and your pet is still having allergy symptoms it is impossible to know if the food contained contaminates or if your pet’s symptoms are not caused by food.
What foods are fed for an elimination diet?
Elimination trials should be done with a prescription diet because these foods are regulated like medications. The ingredient sources and equipment used are certified free of contamination.
There are two categories of hypo-allergenic diets available, limited ingredient and Hydrolyzed. A limited ingredient diet has a novel protein and carbohydrate source that a pet has never eaten. A hydrolyzed diet contains common ingredients that have been pre-digested into smaller molecular components that are too small for the immune system to recognize as allergens.
Some popular elimination diet prescription options:
Science Diet Z/D – Hydrolyzed Purina – HA – hydrolyzed
What about Treats?
Treats are a common source of allergens. Pets on an elimination diet or with known allergies should not be fed table scraps, people food, or other dog or cat foods. If treats are an important part of your routine with your pet, or you are doing training there are treats that we can prescribe that coincide with the diets. You can even use the small kibble from the diet as a treat! Pets on elimination diets should not receive any other chews including but not limited to rawhides, greenies, or bully sticks.
How is a food allergy treated?
Once the offending food substance has been identified, a diet is chosen that does not contain these particular substances. Today there are a number of commercially available, palatable, hypoallergenic diets that can be fed for the rest of your dog’s life. Your veterinarian can discuss the best choices for your pet, based on the results of the food trial. An appointment should be made with your veterinarian at the end of the 8-week food trial to discuss results and next steps.
Occasionally commercial diets containing the right constituents are not available or your pet will not eat them. If this occurs, you may have to prepare a home cooked diet. Your veterinarian can help you formulate a home-made diet that is right for your pet.
Can the problem be cured?
The only treatment is avoidance. Some pets will require medication during severe episodes but most pets can be successfully treated with a hypoallergenic diet.
Is it likely that my pet could develop other food allergies?
Dogs and cats that have developed an allergy to one particular food may develop other food-related allergies in the future. In addition, many dogs with food allergies have other allergies, such as atopy (environmental allergy), flea allergy, etc. If this is the case, your pet’s allergies may only partially improve with a hypoallergenic diet and additional diagnostics or treatments may be needed.
If you think your pet may have a food allergy, you should discuss this with your veterinarian, who can help your pet resume a healthier, “itch-free” life!