Atopic dermatitis or canine atopic disease is a hypersensitivity disease falling into those forms of allergies known as ‘atopic‘, to indicate forms of hypersensitivity towards common antigens (for example, pollen diseases and food urticaria). More specifically, the term ‘atopy’ is currently used as synonymous with allergy or hyperergy, to indicate an abnormal reactivity shown by some subjects in response to certain antigens (defined as allergens) which are completely tolerated by most of the other subjects.
Atopy is an inherited tendency to form excessive IgE antibodies against environmental allergens which, in the specific case of atopic dermatitis, are mainly represented by airborne allergens such as pollens, molds, dandruff, hairs, feathers, insects and most importantly dust mites. However a role can be played also by food allergens, chemicals contained in the fleas saliva and bacterial antigens (Staphylococcus intermedius and aureus).’
Atopic dermatitis in dogs is mainly characterized by pruritus (itching) which affects predominantly the face, feet and abdomen and manifests itself with licking of the feet and scratching and rubbing of the muzzle and the abdomen. This results in dermatitis characterized by alopecia, hyperpigmentation and scabs, and may be complicated by bacterial infection responsible for canine pyodermas. Other manifestations can include tearing due to allergic conjunctivitis, otitis externa, licking granulomas and coat color changes.
Atopic dermatitis treatment in dogs is chronic and usually lasts for a lifetime. Indeed, in most of cases, the disease can be controlled but not cured. The effectiveness of any therapeutic strategy is in fact limited by the impossibility of eliminating all airborne allergens, which are the most important factors responsible for the development of the disease.
Any therapeutic protocol selected has to be preceded and then accompanied by the elimination of fleas with adulticide topical products whose effect lasts for at least 3-4 weeks, and with oral products which inhibit the growth of immature insects. The elimination of fleas (mature and immature forms) from the environment using appropriate products is also recommended. Another preventive measure is pyoderma treatment using systemic antibiotics and topical treatment with appropriate shampoos.
The specific therapeutic protocol for atopic dermatitis treatment in dogs depends on whether itching is localized or generalized, and permanent or transient.
- Transient generalized pruritus. This is a seasonal disease which may last from 4 months to 1 year. The therapy is symptomatic (directed to relieve symptoms) and it is usually based on the oral use of antihistamines and corticosteroids, alone or in combination. It can be also beneficial to include certain essential fatty acids in the therapeutic protocol, as these substances can enhance the action of antihistamines and corticosteroids by restoring the hydrolipidic integrity of the skin and by limiting the production of pro-inflammatory endogenous compounds. In addition, a hygienic treatment with antibacterial and/or anti-itching shampoos is always beneficial.
- Localized pruritus. This is an uncommon manifestation of atopic dermatitis in dogs and it is usually treated with anti-inflammatory creams, ointments or lotions. The preparations usually contain topical corticosteroids alone or in combination with antimicrobials, antifungals or antiseptics.
- Chronic generalized pruritus. In this case, atopic dermatitis treatment in dogs can be based on allergen-specific immunotherapy (or desensitization therapy). It consists in the administration of increasing scalar doses of one or more specific allergens (in form of vaccines) in order to increase the tolerance and reduce the sensitivity of the affected patient towards these allergens. The vaccines are made of a mixture of different allergens and their composition is individualized based on the specific allergens to which a dog is found to be sensitive. The allergen-specific immunotherapy is long-lasting: its beneficial effects are gradual and the improvement of symptoms can be noticed, on average, after 3-6 months from the beginning of the therapy. The effectiveness of desensitization therapy has not to be intended as the disappearance of symptoms, but instead as a more or less pronounced relieve from the itching symptomatology, which allows the reduction of the dosage and/or administration frequency of anti-inflammatory drugs. Moreover, it should be remembered that the effectiveness of allergen-specific immunotherapy is not definitive, as the subject might become hypersensitive towards other new allergens or because other factors might intervene in reducing the patient’s pruritus tolerance threshold. In any case, immunotherapy can be combined with symptomatic therapy (corticosteroids, alone or in combination with antihistamines, administered at the minimum anti-inflammatory dosage recommended) and essential fatty acid treatment.
In conclusion, atopic dermatitis is a chronic condition with a complex pathogenesis and clinical picture, whose treatment often requires the lifelong adoption of several therapeutic strategies. This should be made clear to the pet owner, since the effectiveness of the treatment (although not definitive) greatly depends on his availability and collaboration with the veterinarian. The currently available therapeutic tools hardly allow the definitive recovery from the disease; however they guarantee a satisfying control of its symptomatic manifestations, thereby allowing a ‘peaceful’ coexistence of the atopic patient with his condition.