Investigation of risk factors for mortality in aged guide dogs: A retrospective cohort study.

The overall median lifespan of domestic dogs has been estimated to 9-12 years, but little is known about risk factors for mortality in aged and a priori healthy dogs. The objective of this retrospective cohort study was to determine which characteristics are associated with mortality in aged and a priori healthy guide dogs, in a retrospective cohort study of 116 guide dogs followed from a systematic geriatric examination at the age of 8-10 years old. A geriatric grid collected the clinical data and usual biological parameters were measured at the time of examination. Univariate (Kaplan-Meier estimates) and multivariable (Cox proportional hazard model) survival analyses were used to assess the associations with time to all-cause death. The majority of dogs were Golden Retrievers (n=48) and Labrador Retrievers (n=27). Median age at geriatric examination was 8.9 years. A total of 76 dogs died during follow-up, leading to a median survival time from geriatric examination of 4.4 years. After adjustment for demographic and biological variables, an increased alanine amionotransferase level (adjusted Hazard Ratio (adjusted HR), 6.2; 95% confidence interval [95%CI], 2.0-19.0; P<0.01), presenting skin nodules (adjusted HR, 1.9; 95% CI, 1.0-3.4; P=0.04), and not being a Labrador Retriever (adjusted HR, 3.3; 95%CI, 1.4-10; P<0.01) were independently associated with a shorter time to death. This study documents independent associations of alanine aminotransferase level, skin nodules and breed with mortality in aged guide dogs. These results may be useful for preventive medical care when conducting a geriatric examination in working dogs.