May 2010 Newsletter

Pet Allergies

Sneezing, itchy watery eyes, runny nose, wheezing and hives... These are all signs of allergy season for us as humans but what about our four-legged family members? Although sometimes our animals do have runny eyes and sneezing with some allergies, animals usually have different signs of allergies. Some of these clinical signs can consist of scratching, hair loss, chewing at feet, underside of stomach and the inner thighs as well as recurring ear infections.

Rarely, we may see food intolerance presenting as vomiting and/or diarrhea but most of the time we see food allergies presenting as a skin problem. We also see many inhalant allergies, called atopy, as skin itching and scratching.

One of the most common things that we hear is, "It can't be because of the food, she/he has been on this food for years!" It is important to realize that allergies are a cumulative affect. Allergies are actually from multiple agents. We usually don't see the affect of allergies until the system has reached and surpassed it's "allergy threshold." In addition, when animals are actively showing their allergies, they are very likely to develop additional new allergies to pollens or proteins that they are exposed to. For example, if an animal is having an allergic response to Bermuda grass during the spring and summer when Bermuda grass pollens are at their highest and if at the same time these allergies are active the animal is also eating a diet with lamb in it, the animal could develop an allergic response to the lamb antigen (allergy producing protein).

Allergy Testing

There are a few different ways to test for allergies. It is very difficult to test for food allergies so the only way to determine food is a problem is to perform a food elimination trial. With a trial like this, we look for a diet with one unique protein source and one carbohydrate source that the animal has not been exposed to previously. We usually need to try a prescription diet or a high end pet food store diet as most commercial diets contain too many fillers, additives, and dyes to run a true elimination trial. We can also prescribe diets with "hydrolyzed proteins." These are proteins that have had hydrogen atoms attached to them. When you think of these proteins, it is best to think of a porcupine. It looks much different when it is relaxed versus when it has its spines protruding. Hydrolyzed proteins are difficult for the animal's immune system to recognize as a protein because all the immune system is exposed to are the hydrogen atoms attached to it. When performing the food elimination program we change the diet from the old diet to the new diet rapidly. If we take to long to change the diet, the animal's immune system may develop an allergy to the new protein source. We also eliminate all other flavored items like treats and chews. Just like a person with an allergy to peanuts, all it takes for an animal to react to a protein is to lick a treat or even a bowl that has contained a protein source that the animal is allergic to. After the allergies have subsided with the new food (usually 1-2 months) we can start a dietary challenge where we try one specific protein or carbohydrate or flavor for 5-7 days to see if there is a reaction. Many times, if there is going to be a reaction it occurs within hours of ingesting the allergen.

Allergy Treatment

There is a high degree of variation of allergy treatments among different veterinarians and veterinary dermatologists. This shows that there is not one perfect way to treat any given animal. Each animal is different and has different medical requirements. Antihistamines and steroids are used to control some of the symptoms of allergies. Antimicrobials are used to treat any overwhelming yeast infections or bacterial infections that may arise from the allergies or the trauma from scratching or chewing. Shampoos, sprays and ear medications are used on the skin or in the ears to relieve Allergy 2

the itch and/or treat infections. Cyclosporine (also called Atopica) is a relatively new drug. Previously cyclosporine had been used in humans to prevent rejection of organs/tissues in organ recipient patients. In addition to these treatments we can also use the information from the allergy testing to create a serum injection for each individual animal. We start out at a low dose and gradually build up the amount that is administered to encourage the animal to develop a tolerance to some of the things that the animal is allergic to. This will hopefully bring the amount of remaining allergies down below the animal's threshold so that the allergy symptoms go away or become more tolerable. This is called desensitization treatment.

Allergies in the animal patients can be challenging to diagnose and once diagnosed they can then be challenging to treat. Unlike human patients, you cannot tell the animal to not go have a roll in the grass because he/she is allergic to the grass and it will make them miserable! It is not always easy to find the perfect key to unlock the door to allergy relief for each animal. With perseverance many times we can make our pets more comfortable and bring the sounds of constant chewing, scratching, tag rattling and ear flapping down to a tolerable level. If you have an animal with recurring skin or ear infections, it might be time to consider allergies as a cause for their discomfort.