Risk factors for dental overgrowth in rabbits: A retrospective study using electronic health records

BACKGROUND: Rabbits' teeth grow continuously. Overgrown teeth are a frequent cause for veterinary consultation and can have severe welfare implications. The risk factors for overgrown teeth are incompletely understood. METHODS: Rabbits with overgrown teeth recorded in their electronic health records (EHRs) were identified from a large population of rabbits presenting to veterinary practices (2014-2023). A case‒control study was used to evaluate associations with animal-level characteristics. RESULTS: A total of 1272 narratives describing overgrown teeth in 749 individual rabbits were identified, with incisor involvement in 67.7% of the cases. The proportion of recorded tooth-shortening methods involving clipping declined from 21.4% in 2014 to 4.2% in 2021, with no cases recorded in 2022. Brachycephaly (odds ratio [OR] 1.63, 95% confidence interval [CI] 1.21-2.20), increasing age (OR per 1-year increase 1.08, 95% CI 1.05-1.10) and male sex (OR 1.80, 95% CI 1.45-2.23) were associated with higher odds of dental overgrowth. Neutered rabbits had lower odds of dental overgrowth (OR 0.68, 95% CI 0.55-0.83). LIMITATIONS: The study relied on retrospective EHR data. Misclassification of phenotypes may have arisen from incomplete or incorrect recording in the data. CONCLUSION: Targeted education and preventative health messaging around dental overgrowth may help mitigate the associated welfare implications in pet rabbits.