Objectives: The aim of this case-control study was to identify early-life risk factors associated with the occurrence of owner-reported mobility changes in 6-year-old cats by examining prospective data from a longitudinal cohort study of pet cats, the Bristol Cats study.

Methods: Data on potential risk factors were obtained from seven sequential questionnaires completed between the ages of 2-4 months and 5 years. Mobility-related questions from the study questionnaire distributed at the age of 6 years were used to calculate each cat's mobility score. Cats with mobility scores of ⩾2 and 0 were allocated to the case and control groups, respectively, and the cat's status was the outcome variable.

Results: Of the 799 cats included for analysis, 238 (29.8%) had owner-reported mobility changes. Binomial logistic regression using backwards elimination identified four risk factors for owner-reported mobility changes at 6 years of age: entire neuter status at 6 months of age (odds ratio [OR] 1.97; 95% confidence interval [CI] 1.26-3.07), sustained trauma before 6 years of age (OR 1.85; 95% CI 1.30-2.60), outdoor access at 6 years of age (OR 1.67; 95% CI 0.96-2.90) and overweight/obese status at 6 years of age (OR 1.62; 95% CI 1.13-2.33).

Conclusions and relevance: Risk factor analysis demonstrated that obesity, outdoor access and a history of trauma may predispose cats to developing owner-reported mobility changes associated with degenerative joint disease, whereas neutering before 6 months of age appears to decrease that risk.