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The Daily Vet by petMD

The Daily Vet is a blog featuring veterinarians from all walks of life. Every week they will tackle entertaining, interesting, and sometimes difficult topics in the world of animal medicine – all in the hopes that their unique insights and personal experiences will help you to understand your pets.

Feeding Novel Proteins Is Limiting Allergy Treatment

Skin and ear conditions, caused by pet allergies, are probably the most treated condition in pets, especially in the Western part of the United States. Without veterinary confirmation, most owners attribute these conditions to the food they are feeding to their pets and seek foods with novel proteins (venison, duck, lamb etc.) to feed their pets instead.

Unfortunately is this not only a mistaken response, it also means that veterinarians will have limited ability to treat "real" food allergies in the future.

Facts About Allergies

Most skin and ear allergic conditions are a response to airborne pollens and not food (85-98 percent, depending on whose research is quoted). I know it seems strange, but when allergic animals breathe in pollens, their immune system recognizes the pollen proteins as "foreign." White blood cells and antibodies respond to these invaders by increasing the body’s histamine levels. For pets, elevated histamine levels cause itching, so the animals lick and bite at their skin. Paws foot pads, arm and leg pits, abdomens, and the back of the hind legs are favorite targets. Purple staining of the fur, raised sores on legs, infections between the toes, infected "hot spots" on long haired breeds, and chronic ear "infections" are all symptoms of pollen allergies.

Black, rough, "elephant looking" skin (pachydermatitis) is another classic symptom of pollen allergies. Cats will often exhibit tiny crusts and sores on their bodies called "military dermatitis." "Acne" on the chin or a puffy lower lip called "rodent ulcer" can also be signs of an allergic response to pollens in cats.

Only two patterns of skin symptoms are thought to be characteristic of food allergies. Chronic ear "infections" with red or pachydermatitis rectums (ears and rears) in dogs, and violent facial scratching in cats are suggestive of food allergies. This is not to say that food allergies are not a part of the allergic complex in any pet, but they are probably minor. Pollens are the major culprit.

Pollen allergies are difficult to determine. Expensive blood and/or skin tests are necessary. Treatment generally includes injections to desensitize the pet to the offensive pollen proteins or the use of other expensive drugs. Owners tend to balk at the expense and commitment of this approach. It is often much easier for them to blame the food and experiment with novel proteins. And often this solution is met with initial success, but then fails as time passes because food proteins are not the primary allergens.

The Problem With Treating Allergies

Allergies develop over time due to repeated exposure to offensive proteins. Immediate allergic reactions to pollens and food are rare. Allergic reactions to vaccinations, bee stings, and certain plant residues are exceptions and can occur on first exposure. Since food allergies occur over time, veterinarians treat this condition by recommending proteins that, up to now, were seldom present in most commercial pet foods.

Lamb and rice, salmon, bison, rabbit, venison, and duck with potato were standards for food allergies (novel proteins). Unfortunately owner misunderstanding of allergies resulted in greater demand for foods with these novel proteins, and pet food manufacturers gladly responded. Now, premium foods feature novel proteins as regular ingredients. One brand offers lamb, duck, and venison in the same food! More and more pets are being exposed to novel proteins and will become sensitized to them, and veterinarians will be forced to seek even more exotic proteins for our food allergy patients. We may have to resort to recipes that contain ostrich and emu, kangaroo and wallaby, horse and zebra, guinea pigs and other pocket pets, large snakes, or other wild species the general public may find offensive as food sources, who will then boycott their use or will find them to be too expensive and will be unlikely to purchase them.

The Take Home

Unless your pet has a confirmed food allergy, stick to a food with the more common proteins like beef, chicken, turkey, etc. Do what is necessary to identify the exact source of your pet’s allergies. Reserve the novel proteins in case your pet develops a true food allergy and your veterinarian needs to control the diet. Grain free fits in this same category, which I will address in the next blog.

Dr. Ken Tudor

Image: Shmel / via Shutterstock


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