Owner reported sensory impairments affect behavioural signs associated with cognitive decline in dogs.

To describe the extent of age-related cognitive decline in dogs, information regarding the baseline occurrence of associated behaviours in the general population is necessary. With a seven-item, data driven Age-Related Changes scale, we evaluated the relationship between sensory functions, training, sex, and the occurrence of behavioural signs associated with cognitive decline across the whole adult lifespan. The twofold difference in lifespan between small and large dogs presents challenges for ageing studies, with no widely accepted method to control for body size as it relates to chronological age and longevity, when comparing behavioural signs of cognitive decline. To address this issue, we utilized relative age, calculated using the estimated expected lifespan of the individuals in our questionnaire study. Signs of cognitive decline were already detectable in' Mature' dogs (at 50-75% of the expected lifespan). Visual, auditory and olfactory impairments all resulted in significantly higher scores on the Age-Related Changes scale. Participating in dog training activities was revealed to be protective against behavioural signs of cognitive decline in aged dogs as perceived by the owners. These results revealed possible beneficial effects of training on cognitive ageing and emphasize the importance of routinely screening the sensory capacities of ageing dogs.