A synopsis of Mondino, A., Khan, M., Case, B. et al. Activity patterns are associated with fractional lifespan, memory, and gait speed in aged dogs. Sci Rep 13, 2588 (2023). https://doi.org/10.1038/s41598-023-29181-z

There’s a lot of evidence that exercise improves both physical and mental fitness in older humans. This study explores whether that’s also true for aging dogs. Canine Cognitive Dysfunction syndrome, which affects aging dogs, has many similarities with Alzheimer’s disease. Is it possible that higher physical activity reduces the risk of CCD, like it does for Alzheimer’s?

Natasha Olby and her team at the College of Veterinary Medicine at North Carolina State University monitored the physical activity of 27 dogs, aged 11-15 years, old to look for correlations with cognitive status, joint pain, and gait speed. Her study included dogs from 12 different breeds and mixes, ranging in size from a Dachshund to a Bernese Mountain dog. Because different breeds have different expected life spans, Olby calculated the fractional life span, that is the current age over the expected life span, for each of her subjects.

In humans, gait speed is a reliable predictor of activity. Olby’s team used the ratio of gait speed off leash toward a treat divided by gait speed on leash to account for the differences in dog size. Overall activity levels were measured using collar-mounted monitors. According to owner’s questionnaires, the dogs received anywhere from 0 to 82 minutes of intentional exercise per day, with 23 minutes being the average. 

The owners completed a CAnine DEmentia Scale (CADES) questionnaire. The dogs ranged from normal to severe cognitive impairment, with at least four dogs in each level grouping. Dogs also performed several cognitive tests to evaluate attention, executive function, cognitive flexibility, and working memory. 

Orthopedic and neurological examination was performed in all dogs to evaluate joint pain. Severe pain was rarely found, and most of the dogs were on the lower range of the scale.

They found that older dogs tended to have higher CADES scores, and lower valuate attention, executive function, and memory scores. Aging was also associated with increased joint and spinal pain but not with gait speed. 

Activity monitoring showed that dogs are generally most active between 6 and 9 AM and around 7 PM. Older dogs, however, were less active from 5-8 PM, but more active around 5 AM. Dogs with higher memory scores were more active evenings and weekend afternoons; dogs with lower scores were more active in the early morning. Dogs with joint pain were more active early weekend mornings and dogs with spinal pain were less active in the evening. During weekdays, dogs with faster relative gait speeds had higher activity in the early afternoon.

Do changes in the sleep–wake cycle of dogs influence cognitive function and memory? These data support that hypothesis. Olby also points out that treating diseases that reduce mobility in dogs may help improve cognitive function as dogs age. Gait speed, she concluded, may be useful, but the role of motivation on gait speed needs to be better understood.