Sunday, November 30, 2008

Misconceptions about food allergies

When it comes to pets and allergies, especially food allergies I hear many comments and opinions every day. Many of them and assumptions made are not quite correct, something I want to address today.
Before I get into it, is there an easy way to figure out if your pet may have developed a food allergy? Actually symptoms show pretty obvious. In cats, food allergy usually produces scabs and other signs of itching around the face or neck. A typical canine food allergy shows among others signs of facial itching foot or limb chewing, belly itching, and possibly recurring ear infections.
A food allergy is a reaction to food that involves the body’s immune system. It is usually always a protein particle in the food that is causing those reactions. Your dog may itch, lick, and chew paws, flank, groin, neck, and ears. The itching can be during all seasons. In some instances of food allergy dogs may have chronic ear infections. The dog may also have some gastrointestinal signs such as chronic vomiting, diarrhea, belching, and frequent bowel movements. Food allergy dogs often have both varying degrees of skin signs and gastrointestinal problems that persist.
Coming back to wrong assumptions pet owners make about allergies: Many pet owners believe that a food allergy is to produce intestinal signs as it is the intestinal tract that is exposed to the allergen. Fact is that in pets it is usually the skin that suffers if a food allergy has developed. Food allergy is one of the itchiest conditions in veterinary dermatology. Making matters worse is the fact that food allergies tend to be resistant to cortisone therapies thereby making control of the itching especially difficult.
Next, food allergy is a less likely cause of my pet’s skin disease as I have been feeding the same food for years and the skin problem is a recent development. Again, a wrong assumption. It takes time for a food allergy to develop. This can be months to years. The immune system must be exposed and must develop enough antibodies to trigger an allergic reaction and this requires multiple exposures to the food in question. A reaction to a food that occurs on the first exposure to that food is not an allergic reaction. Such reactions are called “food intolerances” and involve toxins within the food but not an allergic reaction.
Soy and corn are common food allergens and it is best to seek pet foods without these ingredients to avoid problems is another wrong assumption. Latest stats indicate that the most common food allergens for dogs are beef, dairy, and wheat accounting for 68% of canine food allergies. Most common food allergens in cats are beef, dairy, and fish making up 80% of feline food allergies.
“If it looks like my pet might have a food allergy, I should be able to manage the problem by switching to another diet” is an assumption only partially true. Most pet foods contain some sort of mixture of protein sources like beef, dairy, wheat, lamb, fish, and chicken. This means that simply changing foods is bound to lead to exposure to the same allergens. There are two ways to address food allergy: Feeding a diet based on a truly novel protein source. Examples are an exotic diet like venison, duck, kangaroo, rabbit, New Zealand brush tail, ostrich, llama or even alligator. Somewhere I read without further explanation it also could mean feeding a diet with a protein pre digested into units too small to interest the immune system. I really don’t have too much knowledge on this one and will re-address this particular issue after I do some more research.
“My pet got only partly better after the food trial so that means it didn’t work” again is a not correct statement. Animals often and commonly have several allergies concurrently. A food allergy responding to a test diet at the same time an inhalant allergy is active may appear like a partial response. On the other side an inhalant allergy can become inactive should the weather change substantially during the diet trial. This would make a diet appear to be successful by coincidence. In order to determine if a response to a diet trial is real, at the end of the trial the pet needs to be challenged with the original diet. If the itching restarts within feeding 2 weeks of the challenge, food allergy can be diagnosed.

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