Severe itching, especially around the head, may be a sign that your pet has developed an allergic reaction to food. Food allergies in cats and dogs can show up at any age, though they most commonly occur between ages two and six. Learn what types of foods dogs and cats become allergic to most often, and what to do when a change in diet is necessary.
Why Do Pets Become Allergic to Food?
Food allergies occur when your pet’s immune system begins responding to certain proteins during the digestion process. After food is broken down in the stomach, enzymes go to work stripping proteins down to amino acids, which are then fully absorbed. However, there are specialized immune cells in the GI tract that will absorb more intact proteins and present them to the immune system as part of an “environmental survey” process. If the immune system is fooled, the body then views this protein as harmful, triggering your pet’s immune system, which starts to react whenever the offending protein is consumed.
This immune system dysfunction can occur shortly after the protein has been introduced to the diet or even after years of consumption. How the immune system is tricked is poorly understood.
Most Common Cat & Dog Food Allergies
In some cases, pets are allergic to more than one ingredient in the food. These cats and dogs are called “atopic” since they have multiple sensitivities. There’s likely a genetic component to their allergies.
- Cats most often develop allergies to beef, seafood, and dairy products. They can also become allergic to any protein source that is in the offending food.
- Dogs most commonly develop allergies to proteins in chicken, beef, dairy products, eggs, wheat, and soy. Much like cats, they too can develop an allergy to any protein source in the food.
You’ll recognize these ingredients in many commercial dog and cat foods. Allergies sometimes develop after a pet has eaten the same type or brand of commercial food for an extended period of time, so you cannot rule out food allergy just because your dog or cat has been eating their favorite food for a long time.
Symptoms of Pet Food Allergies
Reactions to food allergens include an itchy rash, bumps, scaly skin, swelling, hair loss, sores, hot spots, inflammation, and sometimes vomiting and diarrhea. Itchiness occurs predominantly around the head, neck, face, ears, feet, and under the armpits, but can also affect the entire body. Your pet’s eyelids may become swollen, and you may notice your pet scratching constantly, shaking or rubbing their head, or licking their feet more often.
Diagnosing Dog & Cat Food Allergies
Food allergies can be tricky to diagnose, so it may take a long time to isolate the exact cause of your pet’s discomfort. Once your vet has determined that their symptoms are likely due to diet, an elimination diet may be suggested. This involves removing ingredients from your pet’s diet until symptoms are normalized, using limited ingredient diets. These diets are specifically made for these conditions and use single sources of ingredients like kangaroo and oats, or rabbit and peas.
Alternative Pet Foods to Try
After your cat or dog has been diagnosed with an allergy to a specific protein, commercial food may still be available for your pet. Hypoallergenic pet food that eliminates common food allergens is available. These diets break the protein down into very small particles in hopes that your pet’s immune system will not recognize them.
Pay careful attention to labeling of other commercial products and snacks. If your pet is allergic to beef, make sure to avoid foods and treats that have beef fats and beef proteins. Even monthly heartworm tablets made with beef flavoring can set them off!
Some pet parents try serving home cooked meals to avoid extra ingredients. Be sure to go over any diet changes with your veterinarian or a board certified veterinary nutritionist, and ask about supplement recommendations to ensure that your pet is still getting essential vitamins and minerals in their diet.
More on Pet Nutrition
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Gourmet Pet Foods to Choose From
Grain Free Dog Food: Cut Down on Carbs
This information is for informational purposes only and is not meant as a substitute for the professional advice of, or diagnosis or treatment by, your veterinarian. It has however been reviewed for accuracy by Dr. Joe, a board certified veterinary nutritionist and graduate of Cornell University's program for Veterinary Medicine.