Dogs can develop dementia as they age, like people. They may suddenly switch day and night and fail to recognize their guardian. Scientists have found an easy way to tell if a pet dog has dementia. If the dog's forelimb stride shortens noticeably on walks, it may be a sign of dementia.
A team led by Natasha Olby, a distinguished professor at the College of Veterinary Medicine at North Carolina State University, said on the 25th (local time) in the international journal Frontiers in Veterinary Science that "as with humans, changes in stride in pet dogs are related to cognitive decline," as confirmed by experiments. The study presents a new way to detect canine cognitive dysfunction (CCD), or dog dementia, early and track the course of the disease.
◇Effect on the forelimbs controlled by the cerebral cortex
The researchers leashed 88 senior dogs and had them walk with their guardians along a straight 5-meter path. The dogs were an average of 12 years old, equivalent to 64–72 years in humans. The dogs underwent health checkups and cognitive tests every six months. Guardians filled out the Canine Dementia Scale (CADES) and the Canine Brief Pain Inventory (CBPI) questionnaires.
Stride length was normalized by dividing by shoulder height to account for differences in body size. On average, the thoracic forelimb stride of senior dogs was 1.08 times their shoulder height. The experiment found that for every 10-point increase in the canine dementia scale score, forelimb stride decreased by 1.2%. Dementia scale scores are classified into four stages from 0–95. From 8 points, symptoms appear occasionally as mild cognitive impairment, an early stage of dementia, but from 24 points, the condition interferes with daily life.
In the experiment, unlike the forelimbs, the pelvic hindlimb stride showed no correlation with cognitive changes. Olby said, "The forelimbs play a key role in braking and postural stability, while the hind limbs primarily provide propulsion," adding, "In that respect, forelimb movement is more influenced by the cerebral cortex than the hind limbs."
In humans, Alzheimer's dementia is known to be caused by clumps of amyloid beta protein in the brain. Amyloid beta normally protects nerve cells, but when it detaches and forms aggregates, it damages them. Then the hippocampus, which handles memory, and the cerebral cortex overall shrink. If a dog's cerebral cortex atrophies due to dementia, it can be understood that the dog cannot move the forelimbs properly.
Dogs also become prone to arthritis as they age. It is possible the reduced stride is due to that. But when two dogs with the same arthritis pain level were compared, the one with the higher dementia score had a shorter stride. The researchers said the findings suggest the stride change originates in the brain, not from joint problems.
◇Help for early diagnosis and management of dementia
The researchers said the results do not prove a causal relationship between stride and dementia. You cannot say definitively that a shorter stride causes dementia or that dementia shortens the stride. But they said the correlation appears sufficient.
Scientists have already found in humans that reduced stride is related to cognitive decline. In 2012, the Tokyo Metropolitan Institute of Gerontology tracked 666 people age 70 or older for about three years and reported that those with narrower strides had a 3.4 times higher risk of cognitive decline than those with wider strides. The risk was especially high among women, at 5.8 times.
The medical community believes that if older adults deliberately widen their stride, it not only strengthens hip and leg muscles but also helps improve cognitive function. Using the brain more to control stride naturally enhances attention, judgment, and executive function.
In the same vein, a pet dog's stride can provide data to detect cognitive changes and respond appropriately. The researchers expected that including stride measurements in health checkups from age 7–8, equivalent to middle age in humans, could allow early diagnosis of dementia. While there are no dementia drugs for dogs either, adjusting the environment or diet to match cognitive decline or prescribing appropriate exercise can improve quality of life.
◇Less sleep at night and hearing loss are also signs of dementia
Olby's team has identified several signs that appear when pet dogs develop dementia. According to a 2023 study, senior dogs with higher dementia scores took longer to fall asleep and slept for shorter periods. Delta waves, slow brain waves that appear in deep sleep, also decreased. Poor sleep is known to impair the brain's ability to clear waste, reducing memory ability in dementia patients.
Hearing loss is also a sign of dog dementia. In a paper released in 2022 in the Journal of Veterinary Internal Medicine, Olby reported that dogs can hear 50 dB (decibels, a unit of sound intensity) without difficulty, but dogs with cognitive problems could only hear sounds at 90 dB, equivalent to the noise of a jet taking off.
Hearing loss in dogs with dementia not only reduces quality of life but can have fatal effects on health. Olby said, "In older adults, hearing loss leads to sensory decline and loss of motor ability, increasing the risk of falls," adding, "We confirmed the same association in senior dogs."
References
Frontiers in Veterinary Science (2026), DOI: https://doi.org/10.3389/fvets.2026.1814017
Frontiers in Veterinary Science (2023), DOI: https://doi.org/10.3389/fvets.2023.1151266
Journal of Veterinary Internal Medicine (2022), DOI: https://doi.org/10.1111/jvim.16510
Tokyo Metropolitan Institute of Gerontology (2012), https://www.tmig.or.jp/research/news/albums/abm.php?d=657&f=abm00004726.pdf&n=%E7%A0%94%E7%A9%B6%E6%89%80NEWS_NO.250.pdf