As people age, their movement gets slower. Unfortunately, diminishing locomotory abilities often serve as an indicator of cognitive impairment and dementia. Now, scientists say that this holds true even for man's best friend–senior dogs who exhibit reduced walking speed also slow down cognitively.
A new study by researchers from North Carolina State University has found that a decrease in the gait speed of senior dogs was correlated with decreased cognitive performance, particularly in areas such as attention and working memory. The authors demonstrated that measuring off-leash gait speed can serve as an effective indicator of age-related deterioration and cognitive decline.
"Walking speed in people is strongly associated with cognitive decline. We hypothesized that the same might be true in dogs," said Dr. Natasha Olby, corresponding author of the study, in a statement. The findings were published in the journal Frontiers in Veterinary Science.
Age, Walk and Cognitive Functions
For the study, the team measured the off-leash gait speed of 46 adults and 49 senior dogs. Only the gait speed was measured for the adult dogs who formed the control group. However, the senior dogs were subjected to additional cognitive testing, and their owners were asked to answer a cognitive assessment questionnaire known as the Canine Dementia Scale (CADES).
The scale measures cognitive dysfunction in dogs– a higher CADES score signifies a greater cognitive deterioration. Based on their cognitive test and CADES scores, the senior dogs were sorted into groups. The individual gait speed of the senior dogs was measured in two stages.
First, they were walked by their handlers on-leash for a distance of five meters. Next, they were made to cover the same distance off-leash by offering them treats. "The challenge with measuring gait speed is that dogs tend to match the speed of their handler when on leash, so we measured both on and off leash to see which was the most useful measure," explained Dr. Olby.
She revealed that the authors were initially concerned that the body size and limb length of different dogs could impact their gait speed. "We found that on leash, size does correlate with gait speed, but off leash it doesn't make a difference. Capturing gait speed off leash lets us see the effects of both physical ability and food motivation," Dr. Olby stated.
Slower the Walk, Slower the Mind
It was found that when it came to speed, size was inconsequential in senior dogs. Irrespective of their relative size, dogs in the final 25 percent of their expected lifespan moved significantly slower than adult dogs. "Just as in humans, our walking speed is pretty stable through most of our lives, then it declines as we enter the last quarter or so of our lifespan," expressed Dr. Olby.
The researchers also learnt that senior dogs with slower movement experienced more acute levels of cognitive decline (based on the scores of the owner-completed CADES questionnaires). They also performed poorly on cognitive testing. Additionally, the authors observed that joint pain appeared to have no correlation with walking speed. However, the team noted that none of the senior dogs in the study suffered from severe osteoarthritis and that they intend to address this in future research.
Potential As a Screening Tool
Dr. Olby highlighted that in terms of functional aging, two predictors of morbidity were the most significant: mobility and cognition. "Mobility relies heavily on sensory input, central processing and motor output – in other words, the nervous system – as a result, mobility and cognition are super interconnected. When you have less mobility, the amount of input your nervous system gets is also reduced. It's not surprising that walking speed and dementia are correlated," she elucidated.
The simplicity of the method used in the study could be potentially utilised as a simple screening tool by veterinarians to examine aging patients, according to Dr. Olby. "For me, the exciting part of the study is not only that we show gait speed correlates with dementia in dogs as in people, but also that the method of testing we used is easy to replicate, since it's food motivated and over a short distance," she concluded.
