Atopic dermatitis is one of the most common canine skin diseases, affecting around 10% of the canine population. It is a genetically predisposed inflammatory and pruritic skin disease, most commonly resulting from hypersensitivity to environmental allergens.1,2
Typical allergens causing atopic dermatitis include house dust mites, pollens and mold spores. Many dogs have multiple allergies and may even suffer from a combination of atopic dermatitis and other hypersensitivities, most notably flea allergy.
Each dog may have an allergic threshold. When the level of allergen exposure is below this threshold, there are no clinical signs. Once this threshold has been exceeded, pruritus and skin lesions develop. Any additional factors that cause skin inflammation, such as the presence of fleas or a microbial infection, may contribute to the development of clinical signs. These are known as 'flare factors'.
Any breed of dog may be affected but some are more prone than others. The breed incidence varies geographically as genetic factors contribute to the susceptibility of certain breeds to develop atopic dermatitis. Some of the breeds most commonly reported to be affected by atopic dermatitis include:
Signs of canine atopic dermatitis usually first appear between 6 months and 3 years of age.1 Initially there may be no visible lesions or just erythema. Many of the signs that develop are due to secondary damage caused by self-trauma.
The disease may start seasonally, but usually this progresses to non-seasonal disease, often with seasonal exacerbations. The clinical signs often increase and decrease in severity, depending on the level of exposure to allergens and the presence of secondary infections or concurrent allergic diseases.
Many of the signs that develop are due to secondary damage caused by self-trauma. Other lesions such as pustules, crusted papules and epidermal collarettes may develop due to secondary infections. Signs may also be exacerbated or altered by secondary factors such as the presence of fleas or infections.
The degree of pruritus is typically moderate (for example rated 5-7 out of 10). Secondary infections often increase the degree of pruritus and may make the pruritus poorly responsive to treatment for atopic dermatitis.
Typically, lesions start at friction areas and skin folds:
Some dogs present with only recurrent otitis externa. In chronic cases the skin develops alopecia, excoriation, lichenification and hyperpigmentation.
Dogs that suffer from chronic atopic dermatitis may have a poor quality of life if the disease is not diagnosed, treated and managed correctly.1,2 Veterinarians may follow the 3 steps to continuous comfort and advise pet owners on allergen avoidance.
There are a variety of treatment options for canine atopic dermatitis and a combination of different treatments is often needed to manage it, particularly when it suddenly flares up.
The four main treatment types are:
References: 1. Olivry T et al. Vet Dermatol (2010); 21:233-248. 2. Scott-Muller and Kirk 6th ed (2001);580-581. 3. Ferguson DC et al. In: Riviere JE and Papich MG (eds) Veterinary Pharmacology and Therapeutics, 9th ed (2009);771-802. 4. Steffan J et a. Vet Dermatol (2006); 17:3-16. 5. Olivry T and Sousa CA. Vet Immunol Immunopathol (2001);81:311-316.
Depending on the allergen identified as being the cause of a dog's problem, you could ask an owner to make allergen avoidance a major part of caring for their pet. Some allergens are easier to avoid than others, for example pollens get everywhere and can be very difficult, if not impossible, to avoid.
However, if the allergen is the house dust mite, pet owners could be advised to:
In addition, pet owners should ensure adequate flea control at all times, as flea bites could cause a flare to occur, particularly if the dog is allergic to flea bites.5