US scientists have shown that the stride length of the front legs (but not the hind legs) of senior and geriatric dogs decreases as their cognitive performance worsens. A similar reduction in step length has been well documented in people with dementia. These results suggest that a decline in stride length could be an early warning sign of canine dementia, and so an informative new tool for veterinarians.
In a study published in Frontiers in Veterinary Science, a team at North Carolina State University followed 88 senior and geriatric dogs as part of the Longitudinal Study of Canine Neuroaging. These had been enrolled in the study upon reaching 75 per cent of the life expectancy for their size and breed, corresponding to 12.7 years old on average.
Dogs visited the laboratory for three days every six months for the remainder of their lives. There, they underwent a comprehensive battery of examinations, including tests for cognition, mobility, vision, hearing and strength. Each time, owners were asked to fill out questionnaires about their companion’s health and behaviour.
A filmed assessment of gait speed and stride length formed an integral part of these visits. Dogs were set up to walk at their own pace along a five-metre-long walkway, while being held on a slack leash by the researchers. No verbal encouragement, treats or other external motivations were given to them during these trials. Two key measures analysed were the dogs’ absolute average stride length and their relative average stride length, adjusted for body size.
The relative stride length of the front legs tended to decrease across visits. But more detailed analyses showed that this reduction was not driven to a significant extent by increasing age itself when age and cognition were included in the same statistical model. Rather, the relative stride length decreased with worsening CADES scores, indicating that as dogs age, greater cognitive decline results in shorter strides of the front legs.
On average, a 10-point increase in CADES translated into a 1.2 per cent reduction in the relative stride length of the front legs. In contrast, the relative stride length of the hind legs did not significantly change over time, either in association with greater chronological age or worsening cognitive performance.
