Allergies in dogs
Atopic dermatitis (AD) is one of the most common skin diseases in dogs. 10 to 15% of dogs are said to be allergic. AD is a condition of hypersensitivity induced by environmental factors (allergens) such as dust mites, pollen, mould, or by food. For, recently, food allergies, expressed under the same clinical aspect, have been reclassified in both dogs and humans under the general name of "atopic canine dermatitis".
Pathological mechanism
AD Sensitisation in dogs is predominantly transcutaneous, i.e. the agents remain on the skin and are absorbed by it. The skin therefore plays a role as a physical barrier, which is extremely important in sensitisation. The allergens that pass through this physical barrier are captured by the cells of the immune system (Langerhans cells). These cells activate the defence response and allow the release of chemical mediators that cause skin inflammation and itching.
Clinical signs
The severity of clinical signs varies from one case to another. The first symptoms usually appear between 6 months and 3 years. Itching (skin itching manifested by scratching, biting, licking) is the dominant symptom of allergy. External otitis media is often seen. One often notices an additional infection by bacteria and/or germs (fungi). Diagnosis Currently, there is no infallible method that can diagnose atopic dermatitis.
The diagnosis
is therefore based on clinical aspects, history, exclusion of other diseases with itching (including food allergy), treatment reactions. The allergy tests, intracutaneous tests or blood tests are only useful to define the allergens to which the dog presents a hypersensitivity and thus to establish a specific treatment (desensitisation). Unfortunately, these tests do not allow to identify a food allergy.
Treatments
At present, there is no definitive cure for AD.
The aim is therefore to control the disease and, above all, to prevent its passage to a chronic character.
Management of the patient and the environment :
Elimination of allergens (often impossible to achieve perfectly).
Maintaining the integrity of the skin barrier (skin care, quality nutrition,...).
Reduction of associated infections (germs and bacteria)
Crisis management (control of itching and infections)
Antibiotics, antifungals (if necessary)
Anti-allergics (cortisone, glucocorticoids used with care in a crisis can be well tolerated by dogs)
Control of the disease to avoid crises
Anti-allergic drugs (cortisone, cyclosporine...)
Specific immunotherapy (desensitisation)
Adapted diet (food " sensitive skin ")
A shampoo adapted to the disease: contrary to the ideas received, dogs can be washed frequently if they have dermatological problems.
This article was written in collaboration with Dr Jacques Fontaine. (www.dermatovet.be)