Food Allergy

Pets can be allergic to their food, just like people! You may know someone who has an allergy to food like peanuts, shellfish, or some kinds of fruits or vegetables. In people, the signs of food allergies are often swelling in the mouth and airways, anaphylaxis (in severe allergies), and occasionally skin itching. In pets, skin itchiness is the most common sign of food allergies.

food allergy dermatitis in a cat hair loss

A cat with hair loss from food allergies. Photo from Diagnostic Imaging Atlas.

What causes food allergies?

Food allergies are most commonly caused by a specific protein in food (an allergen). Not every pet will have food allergies, and those with food allergies may not be allergic to the same thing. Some of the common proteins that can cause allergies in dogs and cats are from dairy, beef, or wheat gluten. However, a dog or cat can develop an allergy to any type of protein in their food.

food allergy dermatitis in a dog hair loss

A dog with severe hair loss from food allergies. Photo from Diagnostic Imaging Atlas.

What are signs of food allergies?

Your dog or cat may have eaten the same food for it’s entire life, and just start showing signs of allergies. This is because allergies develop over time, to something we (or our pets) have already been exposed to. Skin problems are the most common signs of food allergies in dogs or cats. Occasionally vomiting or diarrhea may be associated with food allergies, but this is not very common. More often, vomiting or diarrhea will be related to a one-time “stomach upset” and not allergies.

food allergy dermatitis in a cat skin lesion

A cat with lesions on its head from food allergies. Photo from Diagnostic Imaging Atlas.

How are food allergies diagnosed?

Food allergies can be very difficult to diagnose. It requires a lot of time and patience. First, your veterinarian will try to rule out any other cause of the skin issues (like fleas, hot spots, infections, or dry skin). Then he may try an elimination diet for your dog or cat. In an elimination diet, your dog or cat must only eat a very specific diet, one that most pets are not allergic to. A common first try elimination diet is a lamb and rice diet. During the elimination diet trial, your pet may not eat anything else – no treats, no table food, no scraps, nothing accidentally dropped on the floor. Even the smallest bite of a food that has the allergen in it can start a new round of allergy signs. The elimination diet should be exclusively fed for 4-6 weeks. If the allergy signs resolve, we have figured out that your pet has a food allergy! If the signs do not resolve, this could mean one of two things – either your pet does not have food allergies, or he is allergic to something in the elimination diet. In this case, a different diet will be tried for another 4-6 weeks.

food allergy dermatitis in a cat foot lesion

A cat with a lesion on one toe pad from food allergies. Photo from Diagnostic Imaging Atlas.

How are food allergies treated?

The best way to treat a food allergy is by avoiding the protein your pet is allergic to. This usually means feeding a special (often prescription) diet for the rest of your pet’s life. There are some “hypoallergenic” treats available, but it is important to carefully read the ingredients labels to be sure you are not feeding a treat that contains the proteins your pet is allergic to.

Do you have an itchy pet? Do you think it might be food allergies? Call us or come in to get your pet examined. We can help you figure out why your pet is uncomfortable, and help make him feel better!

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