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Allergic Skin Disease

Allergic skin disease is one of the most common skin complaints that we are presented with. Allergic skin disease is an umbrella term covering a variety of causes which can only be summarised here but the main ones include flea bite hypersensitivity, adverse food reaction and atopy. Often these three syndromes will coexist. Here we will concentrate mainly on atopy.

Atopy is a hypersensitivity to environmental allergens such as tree pollens or grasses or indoor allergens such as house dust mites. It results in intense pruritis (itchiness) which becomes a source of distress for both pet and owner.

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Clinical signs include pruritis with hair loss or sometimes just saliva staining around the paws. Depending on secondary factors there may also be evidence of bacterial infection or yeast overgrowth hence the clinical appearance can vary markedly from animal to animal.

Diagnosis is based on seasonal history if outdoor allergens are involved,(though this may become less obvious as the disease progresses), clinical examination of affected areas and pattern of affected areas as it is usually around the head and paws that symptoms are displayed. It is often a diagnosis based on exclusion of other causes of skin disease and this may require general health screening blood tests, skin scraping and biopsy and for a more definitive answer, intradermal testing or immunoglobulin blood testing for specific allergens.

Treatment is aimed at controlling the pruritis and clinical symptoms in an attempt to manage the condition rather than cure it. As mentioned previously, atopy often coexists with or is complicated by other skin diseases. A secondary bacterial pyoderma is common therefore antibiotic therapy may be started. Shampoos are very useful in soothing the skin, improving the skins natural defence barrier and reducing bacterial infections or yeast overgrowths. Antihistamines can be useful to reduce the pruritis but in many cases corticosteroids may have to be used to make the pet more comfortable in the short term. Supplementation of Essential Fatty Acids (EFA) may be helpful in improving the skin barrier which is important as it is the first defence against infection or inflammation. If allergy testing has been performed there may be a possibility of immunotherapy which involves a course of subcutaneous injection of small quantities of allergens.

Good protection against fleas and other parasites is very important and is easily achieved through application of topical spot on preparations. Sometimes we will also look at dietary trials as many animals with atopy will also have food intolerances. This may be in the form of prescription diets or home made diets with a novel source of protein and carbohydrate.

For indoor allergies frequent vacuuming, especially those with filters, washing of pets beds and having wooden flooring rather than carpets will all help to reduce the number of house dust mites and alleviate some of the symptoms. For outdoor allergies walking may have to be limited to certain areas to avoid allergens. Bathing after a walk can also often help reduce the pruritis.
This is only an overview and more information regarding allergic skin disease can be discussed with one of our vets.