Dog Dementia May Be Flagged by Shorter Front-Leg Strides

Dementia can affect dogs just as it affects people and, while it is known by another name, it can be equally heartbreaking for the owners of much-loved pets.

Called cognitive dysfunction syndrome (CDS), or canine cognitive dysfunction, the condition is believed to affect as many as 60 percent of dogs aged over 11.

Canine cognitive dysfunction and its warning signs

Telling cognitive dysfunction syndrome (CDS) apart from ordinary ageing is not always straightforward. Possible symptoms include altered sleep routines and social behaviour, confusion, or becoming disorientated in places the dog knows well.

A new study headed by researchers at North Carolina State University now indicates that dog dementia may have a particular physical marker: a shorter stride in the front legs, also called the thoracic limbs.

The research does not establish that this measure alone can diagnose dog dementia. A dog's gait may be altered by other issues, including persistent pain.

However, the results indicate that front-leg stride length may offer a helpful, objective way to track ageing in dogs when used alongside cognitive questionnaires and veterinary assessments.

"Here we show that the length of front leg stride taken by dogs decreases with age, but even more importantly, decreases with a cognitive impairment," says veterinary neurologist Natasha Olby, from North Carolina State University.

"In fact, we found that the effect of cognitive decline is larger than the effect of age by itself."

Front-leg stride length in ageing dogs

The study analysed 88 older dogs, including females and males, as well as pedigree and mixed-breed animals.

To qualify for inclusion, each dog needed to have reached at least 75 percent of its anticipated lifespan according to its size and breed.

Researchers examined a wide range of variables. The dogs underwent physical, neurological, physiological and orthopaedic assessments covering factors from eyesight and hearing to movement and physical strength.

For the walking element of the research, repeated every six months over several years, the dogs walked along a 5-metre path at their natural pace, with no verbal prompting or treats.

Reduced stride lengths were linked to lower scores in cognitive tests, including after age and chronic health conditions were taken into account - though this association appeared only in the front legs.

"It is fascinating to see that cognitive decline affects front legs and hind legs differently," says Olby.

"In dogs, the hind legs are important for moving forward, while the front legs also change direction and initiate braking.

Walking fluidly involves more than muscles and joints. It also relies on the brain being able to combine sensory information, plan movement and coordinate the body.

"The cerebral cortex integrates more sensory information into the neuronal circuits which produce steps in the front legs, and so loss of high-level sensorimotor integration affects them differently," explains Olby.

Monitoring dog dementia at home and at the vet

Watching for changes in a dog's walking pattern between veterinary appointments - or simply from one day to the next at home - could therefore provide a useful sign of canine dementia.

No specialist equipment is needed, only careful observation. Although a shortening front-leg stride does not necessarily mean a dog is developing dementia, it is a change that should be assessed by a professional.

"These findings support the use of thoracic limb stride length as an objective, scalable functional mobility measure that reflects changes associated with cognitive decline and may be a useful tool for research and clinical monitoring of aging in dogs," write the researchers in their published paper.

Fresh understanding of CDS could potentially also contribute to dementia research in people.

Research has found that people with more advanced Alzheimer's disease generally walk more slowly and take shorter strides than people with milder cognitive impairment.

For dogs, the team wants to examine these measurements and findings in larger canine populations spanning broader age ranges and more varied health conditions.

"If owners notice that their dog's front leg stride is becoming shorter they should visit their vet, for there are possible alternative causes such as arthritic pain or neck issues that can be treated," says Olby.

"If a diagnosis of cognitive decline is made, there are likewise several lifestyle interventions than can be made, even if there is currently no cure."

The research was published in Frontiers in Veterinary Science.