Food Allergies

In food allergy, the history is that of a non-seasonal year round itching, with little variation in the intensity of itching from one season to another. Most reports do not suggest a breed predilection; however, one report indicated an increased relative risk in Labrador Retrievers, West Highland White Terriers, and Cocker Spaniels. The age of onset is variable, from 2 months to 14 yr old. Food allergies may develop in much younger dogs than seasonal allergies. Some pets may have concurrent inhalant allergies, but these are worsened due to the food allergy. The distribution of itching and lesions varies between pets. Ear canal disease that manifests as itching and secondary infection with bacteria or yeast is common and may be the only presenting complaint. Other patterns seen include, generalized itching, generalized oily coat, or a distribution pattern that may mimic that of other allergies (feet, face, and underside) or flea allergy dermatitis (dorsal rump and hind legs). The most common areas of involvement include the ears, feet, groin, under arms, flanks, forelegs, around the anus and muzzle. The degree of itching is usually moderate to severe. Response to cortisone injections varies but is usually poor.

Food allergy remains a confusing allergy to diagnose because there is no reliable diagnostic test other than a strict food elimination diet. The ideal food elimination diet should be balanced and nutritionally complete and not contain any ingredients that have been fed previously to the pet. Many diets contain novel protein or carbohydrate sources. However, if any previously fed ingredient is present in the elimination diet, the pet may be allergic to that ingredient and the diet trial will be a failure. The key point in any food elimination diet trial is that only the hypo allergic diet can be fed. Treats should be confined to fruits, vegetables or rice cakes (unflavored). No raw-hide, pig ears, cow hooves, or other animal-based toys or treats should be chewed on.

The trial diet should be fed for 2 to 3 months. If marked or complete resolution in the itching and clinical signs occurs during the elimination diet trial, food allergy can be suspected. A new diet or new treat may be offered at that time. The return of clinical signs after challenge is usually between 1 hr and 14 days, although it is usually within 3 days. If the pet reacts, return to elimination diet until clinical signs resolve, which usually takes 14 days. At this point, previously fed individual ingredients should be added to the elimination diet for a period of up to 14 days. If a pet does not respond to the initial trial, continue to try other hypoallergenic diets. Sometimes 2-3 trials are necessary to find the diet that does not cause an allergic response. The number of offending food allergens varies from 1 to 5 ingredients per pet. It was once thought that Lamb was a hypoallergenic diet, but more pets react to lamb due to wider availability and use in pet foods. The most frequently identified causative allergens in canine food allergy include beef, chicken, corn, wheat, soy, and milk. Once the offending allergens are identified, control of the food allergy is by strict avoidance of these offending allergens.

Concurrent diseases such as intestinal allergies may also be seen. Allergic gastritis is manifested by vomiting, which occurs 1 to 12 times weekly within 1-2 hours of eating. The vomitus may be tinged with bile. There may also be loose feces. The feces may be extremely odorous, especially in cats. Diarrhea, weight loss, and poor coat condition are usually evident. The prevalence of allergic colitis is greater in cats than in dogs, is often associated with frequent defecation and soft, mucus-laden and sometimes bloody feces. In cats, it is frequently manifested by more normal feces coated or spotted with fresh blood. Both diagnosis and treatment of intestinal allergies Is by a strictly controlled diet.

Food allergy, while frustrating and irritating, can be controlled once the allergens are identified and avoided. Some cases have even seemed to "outgrow" the condition over time.

PLEASE CONSULT OUR CLINIC AT 770-977-9000 IF YOUR PET EXPERIENCES PROBLEMS WITH FOOD ALLERGIES.