A survey of horse owners in Great Britain regarding horses in their care. Part 2: Risk factors for recurrent airway obstruction

Reasons for performing study: Recurrent airway obstruction (RAO) is a commonly encountered respiratory condition of horses. Despite this, the epidemiology of this predominately manageable and reversible disease in Great Britain has been largely ignored. Objectives: To estimate the prevalence of RAO in the general horse population of Great Britain and to investigate possible risk factors for RAO associated with management or early life. Methods: Horse owners were surveyed using a selfadministered postal questionnaire that contained a riskscreening questionnaire (RSQ) designed to identify horses with RAO. These owners were randomly selected, following geographical stratification, using 2-stage cluster sampling of veterinary practices and their clients. Multilevel, multivariable logistic regression models were used to investigate risk factors for RAO in the selected horse population. Results: The estimated true prevalence of RAO in the selected horse population was 14.0% (95%CI 10.7-17.4%). Risk factors for RAO identified in a general horse management logistic regression model included increasing age and exposure to an urbanised environment. Recurrent airway obstruction has long been associated with mature horses while the association with an urbanised environment could be related to different management practices in these areas or possibly air pollution could be involved. The second model associated exposure to hay and respiratory infection in early life with a horse having RAO in later life. Challenges to the respiratory system in early life may be involved in the development of this disease. Conclusions and potential relevance: Recurrent airway obstruction is a significant health problem in the horse population of Great Britain. This form of epidemiological investigation highlights potential risk factors for the disease.