The difference between a food allergy and a food intolerance is that an allergy involves an immunologic hypersensitivity response, whereas a food intolerance involves a direct biochemical interaction without the involvement of the body’s immune defenses. Allergies are typically in response to a protein or glycoprotein such as beef, chicken, eggs, corn, wheat, other grains, soy, dairy, yeast, and nuts (including peanut butter); add fish to the list for cats. Intolerances are typically in response to additives such as sodium-bisulfite/glutamate/nitrate/alginate, BHA, spices, guar gum, propylene glycol, and artificial dyes. (The body can also have a true allergic response to additives.) Allergies usually require more than one exposure to develop, and can get worse with each subsequent exposure; intolerances usually manifest soon after the first exposure. This difference in timing can help to distinguish between the two since they both create similar symtoms including itchiness, scabs, ulcers, rashes, hives, ear infections, diarrhea, vomiting, respiratory problems and asthma, and even seizures. Although there are good tests available for environmental allergies, none yet exist for accurately identifying offending food items.
Food intolerances generally respond well to a diet free of additives. Canned foods have fewer additives than dry or semi-moist foods, and many companies now make dry and canned foods with all-natural ingredients. Food allergies require a diet that doesn’t trigger an immune response, either by using ingredients that are usually hypoallergenic (venison, duck, fish except for cats, potatoes, peas, other veggies) or by using ingredients that have been processed into such small molecular sizes that the immune system doesn’t “see” them (called a hydrolyzed diet). Either way, this should be the only food your allergic pet receives during the diet trial until symptoms are improved enough that other items can be systematically reintroduced. Avoid snacks, table scraps, rawhides, tartar-control chews, cookies (unless the fine print reveals that it’s truly hypoallergenic), supplements containing potential allergens (including gelatin caps), and flavored medications. Diet trials can take weeks to months for gradual improvement, so patience and diligence are essential. An initial veterinary exam is necessary to rule out other possible reasons for your pet’s symptoms, with regular rechecks to monitor and guide the diet trial.
Since food allergic pets often have other allergies (e.g. environmental, insect bites) these should be addressed as well. Frequent bathing with a hypoallergenic shampoo removes pollens and flea saliva that aggravate the allergic response; a good cream rinse afterward prevents the skin from drying out. Air purifiers, frequent housecleaning with hypoallergenic products, removing wool and down bedding, and avoiding perfumes, colognes, hairsprays, and any other scented products (lotions, candles, plug-ins, etc.) can help tremendously. Supplements such as omega-3 fatty acids (cold-water fish oils), antioxidants (vitamins C/E/A, glutathione, selenium, zinc) and bioflavonoids (a.k.a. proanthocyanidins, pycnogenols) help modulate the immune response and prevent damage to tissues. Alternative medicine (e.g. acupuncture, homeopathy) helps to harmonize the body’s immune responses. And lastly, a stress-free home will be more conducive to a calmer immune system, so lots of love!