Canine Atopic Dermatitis (AD) is a genetically predisposed allergic skin disease and is one of the most common inflammatory skin diseases in dogs. The pathogenesis is complex and is continuously being updated as we learn more about this disease.
These dogs are allergic to environmental allergens such as dust mites and tree pollens. These types of allergies, if involving plant pollens, are commonly seasonal due to timing of pollination throughout the year.
Traditionally, it was thought that the animal was exposed to these allergens by inhaling them, however now it is considered that absorption through the skin plays a major role in this disease. Once the animal has had exposure to the allergen, they will mount an exaggerated immune response and develop clinical signs such as itching and inflammation of the skin. Animals with Atopic Dermatitis will scratch, chew, lick or rub areas of the body such as their paws, face, ears, axillae (armpits) and abdomen. The location of the itch can vary between animals and the severity of the itch can vary also. Some animals may only display itchy ears while other animals may suffer from severe itching in many different locations of the body.
A diagnosis is made by ruling out other causes of itching, such as parasites, food allergy, and contact allergy as well as bacterial and fungal infections. The history of the pet’s itching and the sites of itching are assessed by your veterinarian to ensure that they fit with a diagnosis of AD. The normal age of onset for these animals is from six months to 3 years of age. Therefore, a very young or a very old dog that develops a skin problem for the first time, is less likely to suffer from AD.
Once a diagnosis has been made, an allergy test can be performed. The aim of the allergy testing is to identify which environmental allergens the animal is allergic to, not to diagnose the presence of Atopic Dermatitis. The allergy tests that are most useful for Atopic Dermatitis are intradermal skin tests or blood tests. Once the allergens have been identified via testing, desensitising vaccines can be prepared for that animal.
Desensitising vaccines are the only treatment choice which alter the animal’s immune response to benign environmental stimuli. These vaccines aim to desensitise your pet to the specific allergens by giving controlled amounts of the vaccine via an injection or orally under the tongue. Over time, after receiving regular doses of the vaccine, your pet’s immune response will become desensitised to the allergen and will not mount an exaggerated immune response when exposed to the allergen in normal conditions.
There are many other medications and treatment modalities that we can use in Atopic Dermatitis and sometimes a combination of these are needed to control and manage this complex disease.