Environmental Allergies In Dogs And CatsCategory: Blog, Skin and Ear
Allergies in dogs and cats include both food allergies and inhaled allergies. This discussion will focus primarily on inhaled allergies, more properly called atopic dermatitis or atopy. Atopic dermatitis (AD) is a genetically predisposed inflammatory skin disease that leads to itch and recurrent skin and ear infections. Cats with AD may also develop asthma-like respiratory disease as well. AD is common, affecting 10% to 15% of the dog population and many cats as well. High risk dog breeds include: Beauceron, Boston terrier, Boxer, Cairn Terrier, Chinese Shar-Pei, Cocker Spaniel, Dalmation, English Bulldog, English Setter, Fox Terrier, Golden Retriever, Irish Setter, Labrador Retriever, Labrit, Lhasa Apso, Miniature Schnauzer, Pug, Scottish Terrier, Sealyham Terrier, West Highland Terrier, Wirehaired Fox Terrier and Yorkshire Terrier. There is no feline breed predilection. Typical age of onset in dogs and cats is 6 months to 3 years.
Atopic dermatitis is most often associated with antibodies (immunoglobulin E or IgE) to environmental allergens such as mold spores, pollen, dust mites, danders (small scales from hair or feathers, including human hair) and insects. These allergens are inhaled or cause reactions to direct skin exposure. Because many of these allergens are present in greater volume at specific times of the year, AD is often a seasonal disease. Dogs and cats may react to a few or many allergens with symptoms worse in individuals that react to many allergens.
Symptoms of atopic dermatitis include itch, recurrent ear and skin infections. Itchy dogs often spend an inordinate amount of time licking and chewing at their feet. Dogs and cats may both be so itchy that they cause significant self-trauma to their skin and ears. Skin and ear infections are frequently bacterial and/or yeast caused. Because these infections are recurrent, antibiotic resistance is not uncommon.
Diagnosis of atopic dermatitis involves ruling out other causes of symptoms. This includes diagnosing and treating mite infections, flea bite hypersensitivity, non-atopic skin and ear infections, and some autoimmune skin diseases. If pruritis (itch) returns or remains or if infection returns, then atopic dermatitis and food allergies are likely. At this point some veterinarians prefer to rule out food allergies. For more information on this process, please see the food allergy article in the education center: Food Allergies Once the diagnosis of atopic dermatitis is made, allergy testing is performed via serum IgE testing or intradermal testing. The gold standard intradermal testing is performed by a veterinary dermatology specialist due to the high cost of testing reagents. General practitioners offer serum IgE testing as a close second best option which is usually about 75% less expensive. Both of these tests let us know which specific allergens the dog or cat reacts to. This knowledge allows us to formulate allergy shots that are generally part of treatment for atopic dermatitis.
Treatment of atopic dermatitis must include treatment of the symptoms, including skin and ear infections. Bacterial culture and sensitivity testing may be necessary to choose the proper antibiotic in chronic infections. K-laser therapy of severe infections will speed healing and provide rapid pain relief. Most important, we need to prevent further and continued reaction to allergens. The best way to do this is via hypo sensitization using allergy shots. 70% to 75% of pets respond favorably to allergy shots. This number goes up to 90% if we address food allergies at the same time. If allergy injections are not an option, oral medications will also provide relief. Atopica is a skin specific formulation of cyclosporine which modulates the immune system to prevent allergies. Corticosteroids, most often prednisone, will also modulate the immune system to prevent allergies. Atopica is more expensive than prednisone but generally has far fewer side effects. In severe cases, pets may need to be treated with both allergy shots and with an oral medication. It is important to note that treatment must continue for the life of the pet as symptoms tend to rapidly reoccur if therapy is discontinued.
A final note: since response is significantly better in pets that are concurrently treated for both atopic dermatitis and food allergies, at Animal Health Hospital we almost always recommend the above therapies plus diet therapy as well.