Environmental risk factors for canine atopic dermatitis: a retrospective large-scale study in Labrador and golden retrievers.

Background Canine atopic dermatitis (cAD) is one the most common and distressing skin disorders seen in dogs. It is characterized by dysfunction in the skin barrier, with a complex pathogenesis combining both genetic and environmental factors. Objectives To evaluate associations between environmental factors and case-control status in two closely related, at-risk breeds, the Labrador retriever and golden retriever. Animals Two thousand four hundred and forty-five pet dogs, of which 793 were classed as cases (575 Labrador and 218 golden retrievers) and 1,652 as controls (1,120 Labrador and 532 golden retrievers). Methods and materials Case-control status was assigned based upon owner response to a standardized validated questionnaire. Retrospective data on rearing environment were collected via additional questions. Univariate and multivariate logistic regressions were utilized to evaluate associations between environmental factors and case-control status. Results Risk factors included being reared in an urban environment (not living currently in an urban environment), being male, being neutered, receiving flea control and being allowed on upholstered furniture. Protective factors included living with other dogs (not cats) and walking in woodlands, fields or beaches. Additionally, amongst Labrador retrievers, chocolate-coloured dogs were at greater risk of having cAD than black- or yellow-coated dogs. Conclusions and clinical importance This study is the largest of its kind to date to investigate the role of the environment in cAD. Although precise triggers are unclear, this study complements earlier studies in highlighting the protective role of a rural environment and some novel associations with disease development.