Food Allergies in Dogs and Cats
Is your dog or cat itchy and scratchy all year-round? Are recurrent ear infections a common affair in your pet’s world? Does he or she have unresolved soft stool or vomit regularly?
Food allergies are a growing concern for dog and cat owners, and one worth-while test can help your pet feel better.
What is a food allergy?
A food allergy occurs when the immune system of the animal overreacts by producing antibodies that identify specific components within a food (i.e. antigens) as harmful, usually a specific protein or complex carbohydrate. Because antibody production is required for an allergy to develop, food allergies usually occur after prolonged exposure to a food. When the antibodies react with the antigen, symptoms develop.
Are some pets more likely to be affected than others?
Although it is well understood how food allergies affect animals, it is not well known why some dogs and cats experience them, and others don’t. There is no gender, species or age predilection. Any breed may develop gastrointestinal signs of food allergies, although German Shepherds, Wheaten Terrier and Shar-pei are more often mentioned in studies.
It has been shown that animals experiencing increased intestinal permeability caused by conditions such as viral enteritis and IBD, as well as animals with immunoglobulin A deficiency and allergic disease (i.e. atopic dermatitis) may be more at risk of developing food allergies.
Which food ingredients most commonly cause allergies?
Virtually any food ingredient can cause allergies, including meat, fruits, vegetables and grains; however, the most common food allergens are proteins.
Cats most often develop allergies to beef, fish, poultry, lamb, dairy products, and barley/wheat. Dogs most often develop allergies to beef, dairy, wheat, eggs, chicken, lamb and soy.
What are the signs of food allergies?
Food allergies can cause both gastrointestinal and skin issues.
Digestive signs include vomiting, diarrhea or soft stool, intermittent abdominal pain, flatulence, rumbling tummy noises, increased frequency of defecation, itchy bum, and recurrent anal sac irritation and inflammation.
Skin issues caused by food allergies include itchiness, inflammation and infection of the skin on the face, neck, ears, tummy, feet, and around the anus.
Lack of energy, weight loss, hyperactivity and even aggression can be caused by food allergies.
What should I do if I suspect my pet is suffering from food allergies?
If you suspect your pet is suffering from food allergies, speak to your veterinarian. A thorough physical examination and a complete history will help your veterinarian determine the likelihood of a food allergy versus an allergy caused by an environmental allergen (e.g. pollen, dust mites, mold spores, etc.), flea or insect bites, and medications.
If a food allergy is suspected, the most accurate method of providing a definitive diagnosis is to perform an elimination food trial. This involves feeding your pet a diet that contains a limited number of novel and highly digestible ingredients, such as a hydrolyzed or novel protein and novel carbohydrate. A novel ingredient diet is made from foods that your dog or cat has never eaten before.
This diet must be fed exclusively for 8 weeks and strict adherence is critical. Your pet must not be fed food scraps, snacks, odd treats, flavored medications, supplements, and food from other pets in the household. A single violation during the food trial can cause a flare-up of allergies.
What are the diet options?
- A hydrolyzed protein diet where the protein is made unrecognizable by the pet’s immune system such as the Royal Canin Hypoallergenic HP, Royal Canin Anallergenic, Hills Z/D, Purina HA.
- A novel protein diet that does not contain any protein or carbohydrate ingredients previously eaten by the animal. Options include Royal Canin Hypoallergenic SP (duck), Hills D/D (salmon, duck or venison), Rayne Kangaroo.
- A well-balanced home-cooked novel protein diet using ingredients not previously eaten by the animal, containing a novel protein and a novel carbohydrate (e.g. venison and sweet potato)
Only hypoallergenic treats composed of the same ingredient as the trial food can be fed during the elimination period.
What are common items that can cause the elimination diet trial to fail?
A single violation during the food trial can cause a flare-up of allergies. Common items that might negatively affect the trial include:
- Unwashed dishes
- Chewable and flavored medications
- Supplements and probiotics
- Rawhides, antlers, bullysticks
- Pill pockets
- Flavored toothpaste
- Joint supplements and fish oils
What is the next step?
If the animal has a food allergy, gradual improvement in clinical signs is noted.
On week 8, if the signs of allergies have resolved, the next step is to re-introduce suspected food ingredients one at a time to confirm which ingredients are the issue. If clinical signs have not reoccurred after one week of re-introducing one protein or one carbohydrate, another suspected ingredient is added to the diet. If clinic signs reoccur, the animal should return to the food trial diet for two weeks before re-attempting to re-introduce new ingredients.
What about allergy testing?
Intradermal skin or serum allergen testing are unfortunately not recommended as they are unreliable. The only way to diagnose a food allergy is by doing an elimination diet trial.
If you think your pet is suffering from food allergies, book an appointment with us. We can help guide you through the trial and answer any questions that you may have.
LifeLearn, ClientED: Food allergies in dogs. Food allergies in Cats.
Canadian Academy of Veterinary Dermatology. Diagnosing food allergies in dogs: elimination diet trials.
Cote, E. (2015). Clinical Veterinary Advisor, Dogs and Cats. Food Allergy, Dermatologic, 366-367.