Allen M. Schoen, D.V.M., M.S.
Food allergies are simply defined as an allergic reaction caused by the ingestion of particular food substances. Food allergies can be a significant cause of a wide range of symptoms in both people and animals. Some experts estimate that at least 60% of Americans suffer from negative reactions to foods or chemicals on foods. Veterinary experts estimate that 5% of all skin disease and 10- 15% of all allergic skin disease in dogs and cats may be caused by food hypersensitivity. It appears to be the second most common cause of pruritic (itchy skin) skin disease in cats and the third most common cause in dogs according to Dr.’s Tilley and Smith in “The Five Minute Veterinary Consult”. Along with food allergies, one has to also consider allergic reactions to medications such as medications for heartworm prevention, flea prevention, antibiotics as well as additives to the foods such as preservatives, artificial food colors and flavors etc.
Food allergies can show up at any time and can mimic other hypersensitivity reactions. It is easy to differentiate from seasonal allergies, because food allergies occur all year round, as long as your pet is on the offending food. There does not appear to be any sex or breed predilection, though german shepherds and labrador retrievers seem to have a high incidence of food allergies in my practice.
Food allergies can not only affect the skin, but they can also affect the gastrointestinal system and rarely the nervous system. Typical skin symptoms include severe pruritis (itching), hairloss, redness (erythema), skin infections and ear infections. Gastrointestinal signs include vomiting, diarrhea, sometimes bloody diarrhea and straining and increased frequency of bowel movements. Rarely, seizures have been associated with food hypersensitivity. In people, food allergies have also been associated with irritable bowel syndrome, hyperactivity, depression, headaches, irritability, arthritis and joint pain, asthma, chronic bronchitis, hypoglycemia and sinusitis. Occasionally I feel like I have seen some of these symptoms in dogs and cats associated with food allergies, but that is difficult to document.
How do you know if your pet has food allergies? If your furry friend has any of the above symptoms, you should check with your veterinarian. Sometimes, you can figure it out just by doing a bit of simple detective work. Check when the itching or other symptoms began to show up. Was it right after you changed your dog or cat foods? If so, that is easy enough to figure; change back to the former food and see if your pet stops itching or whatever the problem was. If it clears up, you have a very simple answer.
Food trials are actually probable the easiest way to figure out food allergies. I usually recommend a food elimination diet as our first attempt to diagnose food allergies. The ideal way to do it is to limit your pet to one protein source and one carbohydrate source that they have had none or limited exposure to previously. For instance, if your pet was on a basic generic dog or cat food and it had wheat and corn and beef as its main ingredients you might want to choose either a homemade diet of fish and potatoes or one of the prepared hypoallergenic diets of prepared fish and potatoes. The challenge with these trials is being patient. Ideally you should see some improvement of the problems within four weeks. however sometimes it may take as long as three months and there have been reports of food elimination trials where symptoms did not improve for six months.
Most of the time though, I see improvement within a few weeks. Once you have realized that your pet is allergic to a particular pet food, then the question is what product in it is causing the allergies. Is it the carbohydrate source such as wheat or corn, or the protein source such as beef or chicken? Could it be something else entirely like the artificial colors, flavors or preservatives? All of these are possible. One can simply add one food source back at a time, which is commonly known as a food provocation trial. For instance, if you add back wheat and the symptoms reoccur you know that that is the offending allergen. The most common food allergens for pets include: beef, chicken, pork, what, corn, soybeans, eggs and dairy products. During this avoidance trial you will also want to avoid antibiotics and steroids, heartworm medications and any other potential offending substances. Also be aware that certain toys and snacks such as bones or other chewables may have offending substances in them as well and therefore need to be removed during food elimination trials. There are blood tests for food allergies, but there is still some controversy about how reliable they actually are. Food allergies can also mimic other diseases including other allergies such as inhalant or contact allergies, flea allergies as well as parasitic infections.
Once you have diagnosed that your pet has a food allergy, what can you do about it? The easiest thing of course is to avoid the offending allergen. That is definitely what you want to do. Normally, to make life simple, you can find a particular brand of dog or cat food that they do not react to. However, sometimes, this can be easier said than done with all the different foods and chemicals that are in a pet food. Some people choose to cook a homemade diet for their pet and figure out which individual foods they are allergic to. Though this can be quite time consuming, I have seen the most improvement with pets that are cooked a homemade balanced natural diet, avoiding the offending substances. These pets seem to thrive much more, as long as it is a well balanced homemade diet. Balanced homemade diet recipes can be found in books such as Dr. Pitcairn’s Guide to Natural Health for Dogs and Cats as well as a number of homemade diet books published by dog breeders and owners as well as in my book “Love, Miracles and Animal Healing”.
Sometimes, simple nutritional supplements may also benefit a pet with food allergies. Supplements that I recommend include a good essential fatty acid supplement such as organic refrigerated flax seed oil or black currant oil or evening primrose oil at a dose of about one teaspoon daily for a 50 lb. dog. . In addition, I will use digestive enzymes and supplements such as quercetin (a bioflavinoid ) and bromelain (pineapple source digestive enzymes) combined. They actually help prevent the release of histamines in the gastrointestinal tract. There are other natural supplements I prescribe for more challenging patients.
To give you some examples of food allergies, I once treated a cat that had been on all sorts of medications for chronic itching including cortisone, hormones, antibiotics and it was still itching and getting worse. When I first saw the cat, I suggested stopping all medications and just trying a simple balanced diet. The itching and skin problems resolved within two weeks and we had a happy kitty! One time I saw a german shepherd with a history of all sorts of skin and gastrointestinal problems, including itching, loss of hair, ear infections, skin infections, diarrhea and straining to defecate. He too had been on all sorts of medications. Three weeks after we put the dog on a natural diet, all the symptoms resolved and we had another happy camper! Not all are that easy, but it is surprising what a proper balanced change of diet can do! Eat naturally and be well till next time!
If you would like a consultation with one of my Veterinary associates in the greater New York or Connecticut region, you can go to the practice part of my website, call the appropriate office and make an appointment with one of them to see how we can help your kindred spirit.
No article can replace the services of a trained veterinarian. This article is not intended to encourage treatment of illness, disease, or other medical problems by the layman. Any application of the recommendations set forth in this article is solely at the reader’s discretion and risk. You should consult a veterinarian concerning any veterinary medical or surgical problem. If a veterinarian is caring for your pet, for any condition, he or she can advise you about information described in this article.