The epidemiology of upper respiratory tract disorders in a population of insured Swedish dogs (2011-2014), and its association to brachycephaly.

Upper respiratory tract (URT) disorders are common in dogs but neither general nor breed-related epidemiological data are widely reported. This study´s aims were to describe the epidemiology of URT disorders in a Swedish population of dogs and to investigate whether brachycephalic breeds were overrepresented among high-risk breeds. A cohort of dogs insured by Agria Djurförsäkring in Sweden (2011-2014) was used to calculate overall and breed-specific incidence rate (IR), age at first URT diagnosis and relative risk (RR) for URT disorders. For breeds with high RR for URT disorders, co-morbidities throughout the dog's insurance period and age at death were investigated. The cohort included approximately 450,000 dogs. URT disorders had an overall IR of 50.56 (95% CI; 49.14-52.01) per 10,000 dog years at risk. Among 327 breeds, the English bulldog, Japanese chin, Pomeranian, Norwich terrier and pug had highest RR of URT disorders. Eight of 13 breeds with high RR for URT disorders were brachycephalic. The median age at first URT diagnosis was 6.00 years (interquartile range 2.59-9.78). French bulldogs with URT diagnoses had a significantly shorter life span (median = 3.61 years) than other breeds with URT diagnosis (median = 7.81 years). Dogs with high risk for URT disorders had more co-morbidities than average.