Association between passive smoking and atopic dermatitis in dogs.

Onset of atopic dermatitis and occurrence of related skin lesions are influenced by various environmental factors in humans, and companion animals. Several studies have demonstrated an association between passive smoking and the development of atopic dermatitis in children. This association has never been investigated in the dog to our knowledge. We enrolled 161 dogs seen at dermatology and vaccination consultations over a six-month period for this study. Dog owners were asked to complete a questionnaire, to evaluate the exposure of the dog to tobacco smoke. The atopic or non-atopic status of the dog was assessed on the basis of Favrot's criteria (history, clinical examination and cutaneous cytology for Malassezia). Analysis of the data for the 161 dogs enrolled revealed a significant association between high levels of passive exposure to tobacco smoke (cigarette consumption divided by the area of the home) and the presence of atopic dermatitis in the dogs (OR, 4.38; 95% CI, 1.10-17.44; p=0.03; NNH (number needed to harm) 3, 95% CI 2-52). The prevalence of atopic dermatitis showed a slight, but non-significant association with breed predisposition. Dogs with high levels of exposure to tobacco smoke may have a higher risk of atopic dermatitis than non-exposed dogs.