Importance: With a growing companion animal population and their extended lifespans in South Korea, the need for health examinations tailored to specific life stages is increasing. However, an objective standard for defining these life stages is currently lacking.
Objective: To classify life stages for companion dogs and cats by identifying clusters in age-specific disease proportions derived from medical records, providing a data-driven foundation for health examination programs.
Methods: We collected 505,667 medical records from 82 veterinary facilities in South Korea between 2020 and 2023. Diagnoses were standardized using GPT-4o and S-BioBERT. Following preprocessing, data from 27 facilities yielded 222,706 canine and 39,910 feline records for the final analysis. Principal component analysis and K-means clustering (K = 4) were applied to age-specific disease proportions to identify life stages. The 10 most highest-proportion diagnoses diseases were determined for each cluster.
Results: Canine life stages were classified as ≤ 1 year, 2-5 years, 6-10 years, and 11-15+ years. Feline life stages were 1-2 years, 3-8 years, 9-12 years, and 13-15+ years. In dogs, developmental diseases were common in the youngest age group, while chronic diseases were more prevalent in older groups. In cats, oral and urinary diseases were high-ranking, conjunctivitis was most common in the early stage, and chronic diseases increased with age.
Conclusions and relevance: Age-specific diagnosis patterns support four practical life stages for dogs and cats in South Korea. These boundaries can inform evidence-based preventive examination schedules, animal health policy, and pet insurance product design.
Keywords: Dogs; age groups; cats; cluster analysis; electronic medical records.
© 2026 The Korean Society of Veterinary Science.