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Skin Allergies in Cats and Dogs

Allergies occur when the immune system overreacts to a foreign body or allergen. In dogs and cats skin allergies present in many different forms, but in NZ, we see three main forms : atopy, flea allergy dermatitis and food allergy

Atopy is a generalized skin allergy caused by environmental allergens such as pollens, house dust mites, moulds and animal dander . These are often inhaled, as in human hay fever; but in dogs, results in acute itchy skin rashes. Occasionally dogs will also get allergic conjunctivitis, rhinitis & bronchitis but as an exception to the rule. In cats, generalized scabby lesions and overgrooming are more common. (Secondary hairball problems often happen in cats because of this.)

Diagnosis is made by ruling out other causes of itchy skin rashes such as mange mites; skin infections with bacteria or fungi, fleas, lice and food allergies. Sometimes skin or blood testing can be done to help pinpoint the exact allergen.

The occurrence of an allergy in a pet depends a lot on its genetic predisposition; as well as exposure to the allergen. Some breeds are known to be prone to allergies: Terriers, Shar-Peis, Labradors, Setters, Retrievers, Poodles, German Shepherds, Miniature Schnauzers, Pointers & Dalmations.

The main symptom is itching , predominantly around the face, belly, feet and ears. Constant scratching or licking damages the skin & leads to secondary infection & sometimes “Hot Spots”. Atopy is frequently seasonal especially when the allergen is a pollen. Plants such as Wandering Jew, Willow Weed, Privet, Acacia and Pine Pollen are common allergens.

Ideally, allergies are treated by avoiding the allergen. However,as identification of the allergen is difficult and expensive , and avoiding it extremely impractical in many cases anyway, treatment is most often by using drugs to dampen down the immune system. Corticosteroids such as prednisone are most commonly used. These are relatively cheap but can have some side effects in some patients. Cyclosporin (“Atopica”) is a much more expensive drug, but very effective and with much fewer side effects.

Hyposensitisation therapy (usually by a skin specialist) is also possible in dogs. Its effectiveness varies but it provides at least some relief for around 75% of pets treated.

It is always worthwhile eliminating known allergens from your pet’s environment:- e.g. Wandering Jew, Privet & Willow Weed.

Flea Allergy Dermatitis is caused by an allergy to the flea’s saliva which is injected into the dog or cat’s skin when it feeds. The usual area affected is the pet’s back especially around the tail-base, but the whole skin area can be affected and again secondary “Hot Spots” are common.

Eliminating fleas from your pets environment (by treating all your pets regularly with a highly effective flea treatment )is essential in the treatment of FAD. Sometimes a course of corticoids is also necessary to break the “Itch Scratch Cycle”

Food Allergy is much less common in dogs but is well worth ruling out as it is manageable without drugs once the allergen is identified.

The most common allergens are proteins such as beef and dairy products. Cereals can also, less commonly, cause food allergies (e.g. wheat, corn, soya).

The main signs are similar to atopy- ie itchy, inflamed skin. Sometimes vomiting and diarrhea may also be present.

Food allergy is diagnosed by first demonstrating an improvement after 6-10 weeks on a hypoallergenic diet such as Hills z/d. Proteins can be introduced one at a time, and the pet monitored for a reaction.

Once the allergen(s) are identified the pet can be fed diets excluding those proteins, or kept on the Hills z/d diet.

It is most important to realize that allergies are generally not curable. Allergic pets need to be managed through their lives by avoiding the allergens as far as possible, and using drugs when “challenged” by allergens.

 Check out our clinic showrooms for Hills Prescription food products.