Daniel P. Carey, DVM and Gregory Reinhart, Ph.D.
In the United States, it’s estimated that at least 15% of all dogs suffer from allergies. Owners of allergic pets are all too familiar with these signs: itching; dry, flaky skin; and dull coats. However, some new developments in allergy research promise to provide at least some relief for dogs – and their owners.
Allergies are an immune system reaction to a substance the body deems foreign. For some reason, that particular substance provokes the immune system into putting major efforts into fighting the intruder. Because the body is very sensitive to that substance, we say that the body is hypersensitive to the substance or shows increased reactivity to it.
The substance which does the provoking is called an antigen. It can be any substance capable of producing a detectable immune response. An allergen is an antigen that produces an allergic response.
Although there are many allergic skin conditions common to dogs and cats, three specific problems represent the bulk of cases: flea allergen sensitivity, inhaled allergen sensitivity (atopy) and food allergies.
Flea allergies comprise the greatest number of allergy cases, followed by aller-gies caused by inhaled airborne allergens. Food allergies are poorly understood and often misdiagnosed, so their true Incidence rate is difficult to estimate.
Flea Allergen Sensitivity
The most common allergic reaction encountered by pets is caused by the bites of fleas. Flea Bite Allergic Dermatitis (FBAD) affects both sexes and all breeds. It commonly appears in animals between 3 and 5 years of age. Those animals especially sensitive to inhaled allergens (for example, pollen) are often extra sensitive to flea bites.
Pets with FBAD often exhibit excessive itching and loss of hair on the lower back and thighs. The itching may be mild or intense and often involves the neck area.
The presence or absence of FBAD is related to the flea population. For example, in states with long winters, the flea population is effectively kept at a low, only to boom with the onset of warmer spring weather. However, when animals are constantly exposed to fleas, they are less likely to suffer from FBAD than those exposed seasonally. The FBAD reaction depends upon the duration and constancy of exposure.
The typical treatment for FBAD is corticosteroid therapy, which effectively reduces the itching characteristic of FBAD. More and more veterinarians, however, are concerned with the side effects associated with corticosteroids. New research has shown that dietary fatty acid adjustments have positive effects on dogs.
Inhaled Allergen Sensitivity or Atopy
Allergic reactions due to inhaled allergens such as pollen are known as atopy. They’re the second most common allergic reaction in pets.
The first reaction dogs usually have is itching on the feet and forelegs. Itching of the face, ears and neck are also common. In severe cases, dogs may show signs of dandruff, inflammation of the outer ears, or even skin redness.
Studies have shown that dogs are more likely to be genetically predisposed to atopy than cats, and that, in particular, several breeds tend to more commonly develop atopy. These include Boxers, Lhasa Apsos, Golden Retrievers, Labrador Retrievers and Shar Peis.
Dogs are most often affected by atopy between 1 and 3 years of age, with females more often affected than males. Since the first sign of atopy is often itching, and that’s also the main symptom of other allergies, a thorough veterinary examination is needed to distinguish atopy from others.
Atopy often worsens with age if not identified and treated properly. Animals are exposed to allergens in two ways: the offending allergen may be inhaled or absorbed through the skin. This latter process makes the use of rinses and shampoos especially important for treatment and management, as keeping the allergen off the skin helps solve the problem.
Corticosteroids are an effective medication in managing atopy. Another treatment is hyposensitization (“allergy shots”), which makes the body more tolerant of antigens. This delays or lessens the allergic reaction, and is effective in 75% of cases within nine months of treatment.
As a pet owner, you can help manage your pet’s allergies by applying cool water rinses to reduce itching; using shampoos and moisturizers; and treating bacterial infections on the skin promptly. In addition, as with FBAD, fatty acid adjustments in the diet can also have a positive impact.
Food hypersensitivity comprises about 10% of hypersensitive allergic cases. Distinguishing between a true “food allergy” and an “adverse reaction to food” can be difficult. An “adverse reaction to food” is associated with ingestion of a certain food ingredient and the subsequent appearance of symptoms. The term “food allergy” refers to an adverse reaction based on a proven response from the immune system (for example, the release of antibodies), and is less common than an adverse reaction to food.
How do you tell if your dog has an adverse reaction to food? Simply by eliminating the suspected food from the diet, and watching to see if the symptoms disappear. To complete the test, check to see if the symptoms reappear when the food is introduced again.
In true cases of food allergy, the hallmark sign is itching, not unlike the itching present in FBAD and atopy. Other symptoms of food allergy in dogs include recurrent ear inflammation, hives and itching.
The only effective way to manage food hypersensitivity is to remove or avoid the offending allergens. Because most food allergens are proteins found in the diet, the first step is to change the dog food you are using. If your dog has been having reactions to a food based on beef or meat meal, switch to a food made from chicken. If your dog has problems on a chicken-based food, try a lamb food. Remember that many foods contain a variety of proteins, including egg, in varying quantities. One of those could be the culprit, so some experimenting is needed to pin down the source of your dog’s sensitivity. Read the ingredient panels of different foods.
You should be able to find a good commercial diet which your dog can enjoy without problems. Occasionally, a home-cooked diet may be suggested. Aside from the lack of convenience, cooking for your dog presents the problem of ensuring that your pet eats a complete and balanced diet. But with the many new options available commercially, cooking shouldn’t be necessary.
New Concepts In Allergy Management
Research has shown that two dietary factors can help reduce the allergic load (the amount of allergens presented to a sensitive individual) and decrease a pet’s pruritic threshold (the point at which an allergic condition manifests itself as itching). An optimal ratio of omega-6 to omega-3 fatty acids, and the use of limited, highly digestible proteins in the diet, actually help manage allergic inflammation at a cellular level.
In conclusion, working with your dog’s diet may help you handle the allergy problem without resorting to drugs, or help your dog progress further than with drug therapy alone. By combining an optimal diet with appropriate medications, it’s possible to effectively alleviate allergy symptoms your dog may have. You should ask your veterinarian about current treatment methods and clinical allergy diets.
Dan Carey, DVM, is Director of Technical Communications for The Iams Company. He has been in private practice and nutri-tional research. Greg Reinhart, Ph.D., is a Research Nutritionist for Iams. Illustration by Susan Solotoff.