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Allergic Dermatitis, Atopy
Allergic dermatitis (atopy, atopic dermatitis) is the predisposition to allergic disease in response to environmental allergens. One of the most common source of allergens causing atopy is the house dust mite. Tree, grass and weed pollens can also cause this disease. Flea allergic dermatitis and parasitic infections such as sarcoptic mange (scabies) and otodectic mange also cause allergic-type reactions.
Signs and Diagnosis of Atopy
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Most allergic pets do not start with severe itching (a pet with severe itching is more likely to have mange, fleas, or food allergies). With time, many dogs with chronic allergy develop pink or red skin, bronzing and darkening of the skin. The bronzing color is from pigment in the dog's saliva that discolors the skin and the hair. Darkening of the skin, called hyperpigmentation, can develop in any chronic skin disorder as the result of repeated trauma and inflammation.
- Foot licking, recurrent ear inflammation, face rubbing, itching of the armpits and groin in a young animal is very suggestive of atopy.
- Most common staphylococcal bacteria infect the skin, causing small red bumps called papules or small pimple-like lesions called pustules. Scabs can also form when the papules or pustules rupture.
- Secondary yeast infections are common in allergic dogs. Dogs become itchy, greasy (with greasy yellow scales), red and quite smelly.
- Diagnosis is based upon clinical signs and various skin tests (skin scrapings, fungal cultures etc.) and blood tests.
However, diagnosis of allergies is a complicated task. The investigation of a suspected allergic dog should include rigorous treatment for external parasites and secondary bacterial and yeast infections which often complicate and contribute to the itch. A diagnosis of food intolerance is made in 2-10% of "itchy" dogs. It can be controlled without using drugs and is worth ruling out by introducing an elimination diet followed by dietary challenge to confirm the diagnosis. Elimination diets are time consuming and require considerable owner commitment. It can be up to 3 months before the dog stops scratching. Once other causes of itch have been ruled out, specific tests to detect allergic antibodies to environmental allergens can be undertaken to confirm the diagnosis of atopy.
Breed Predisposition
Veterinary dermatologists recognise that certain breeds are predisposed to develop allergic skin disease and that the tendency to develop atopy is often inherited. Breeds with a high incidence of allergies include Cairn Terrier, Shar-Pei, Lhasa Apso, West Highland White Terrier, Scottish Terrier, Shih Tzu, Wirehaired Fox Terrier, Dalmatian, Pug, Irish Setter, Boston Terrier, Golden Retriever, Boxer, English Setter, Labrador Retriever, Miniature Schnauzer and Belgian Tervuren.
Treatments For Atopic Pets
Unfortunately, dogs rarely "grow out" of their allergies and most atopic dogs require lifelong therapy. Various treatments are available and your veterinarian will recommend the best regime.
Next: Conventional and Natural Treatments for Allergic Dermatitis
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