ObjectivesThe UK dog population is living longer, raising concerns about their welfare as a result of ageing‐related diseases. Our primary objective was to determine when dogs enter the “old age” life stage based on free‐text clinical narratives in veterinary electronic health records. In addition, to identify common conditions documented during consultations with old dogs.Materials and MethodsRegular expressions were developed for: ageing, elderly, geriatric, senior and old. These were used to search the veterinary clinical narratives within a large database of veterinary electronic health records. A sample of 1000 consultations were then read, and those confirmed as being old age classified according to a modified scheme based on the World Health Organization International Classification of Disease 10th Revision.ResultsA total of 832 old age dogs were identified. The age at which veterinary professionals considered dogs to be in old age was over 7.25 years in 95% of patients (median age 12.5 years). This age varied among the most common breeds, with cocker spaniels being younger (median 11.7 years) compared with Jack Russell terriers (14.1 years). Weight‐related (289/832 consultations, 35%), musculoskeletal (278, 33%), dental (254, 31%), integumentary (235, 28%) and digestive (187, 22%) conditions were most common. The odds of a dental condition were greater (odds ratio: 2.71, 95% confidence interval: 1.38 to 5.31) and musculoskeletal condition less (odds ratio: 0.36, 95% confidence interval: 0.17 to 0.81) in cocker spaniels than in a mixed breeds reference.Clinical SignificanceThis metric applied at scale to identify old patients may provide a novel foundation for timely health interventions targeted to dogs at increased risk of developing various age‐related conditions.