Taking the Itch Out of Allergies

Watching our pets chew, lick and scratch. This can be a frustrating and heart wrenching to watch. What causes the itch? This article is designed to discuss allergies and the treatment options available to help take the mystery out of the itch. I will caution this article describes chronic allergies (not anaphylactic reactions) in healthy pets only.

Allergies are defined in Doorland's medical dictionary as "a state of hypersensitivity induced by exposure to a particular antigen (allergen) resulting in harmful immunologic reactions to subsequent exposures". What that translates into is our pet's immune system goes a bit awry. Rather than just destroying harmful environmental invaders (infections, etc) exposure to these allergens triggers the release of certain chemicals (histamines, leukotrienes, etc) that cause itching, rashes, etc. Repeated exposure causes a more severe response.

Allergies in pets are divided into four major categories:

1) Flea allergic dermatitis–if your pet has fleas it is going to itch. Unfortunately, some pets will react severely to a small number of fleas. One flea bite can cause a rash to break out all over the body (even in areas nowhere near the flea bite). If you suspect fleas I recommend purchasing a flea comb at a pet shop or from your veterinarian to check for fleas and if seen talk to your veterinarian about safe, effective flea control.

2) Food allergies–this refers to a reaction to certain proteins in foods. The best way to prevent food allergies is to not give table food to your pet and stick with one diet. In severe cases special diets (either prescription or homemade) may be necessary.

3) Contact dermatitis–this is an allergic reaction to something the skin comes in contact. Usually we will see a rash break out in either hairless areas (the abdomen, bottoms of feet, etc). Most commonly we will see this with exposure to detergents or chemicals. Stick with one detergent in washing your pet's bedding and do not let your pet lay on areas that have just been cleaned or treated with chemicals or detergents (floors, rugs, patios, lawns, etc). If a severe rash breaks out see your veterinarian right away.

4) Atopic dermatitis–this is a genetic predisposition to become allergic to normally innocuous substances. What does that translate into: seasonal allergies. The five major classes of seasonal allergens are grasses, weeds, pollens, mold spores and dust mites. Any pet of any age can develop seasonal allergies at any age but certain dog breeds (Golden Retrievers, Labrador Retrievers, Boston Terriers, West Highland Terriers, Lhasa Apsos, Pugs, Schnauzers, English Bulldogs, Dalmations, English and Irish Setters) are considered "at risk" and atopic allergies usually develop at a younger age (before three years of age). No at risk breeds have been reported in cats.

This is the most frustrating type of allergy for both pet owners and veterinarians because depending on the time of year these allergens will be in higher concentrations in the environment and your pet will have a reaction. Less severe cases require either antihistamines or short courses of cortisone but in some cases secondary infections to normal flora occur. Normal flora refers to the small numbers of bacteria and yeasts that live on the body in small numbers and are kept in check by the immune system but will overgrow if the situation is right (allergic rash on the skin, ears, or both). In severe cases pets actually need medications like antibiotics and antifungal medications in conjunction with something for the itch. That gives the false impression that this is just an "infection" and should be completely cured once the medication is finished but if you do not address the allergy that triggered this then you are ignoring the real problem. Using medications as "quick fix" too often without addressing the allergy can cause more problems than they solve. If your pet is suffering from seasonal ear and skin problems and your veterinarian is suspicious of atopic dermatitis I would recommend discussing a referral to a veterinary dermatologist.

I hope this takes some of the mystery out of the "itch" and will provide for a healthy discussion with your veterinarian at your next visit.

Matt Kearns, DVM

March 21, 2008

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