Canine Dementia May Help Advance Human Medicine

Pets are living longer than ever, but advancing age also brings a greater chance of cognitive decline resembling human dementia.

Cognitive dysfunction syndrome in older dogs

In dogs, this condition is known as cognitive dysfunction syndrome (CDS). It is a subtle, gradually worsening illness that can develop so slowly that even highly attentive owners may not recognise it.

Like people with Alzheimer's disease, the most prevalent type of dementia, dogs with CDS may experience difficulties with learning, memory and executive function.

The neurological symptoms are "very unspecific", but can include disorientation, changes in social behaviour, house-soiling, anxiety and disrupted sleep–wake patterns. A dog may no longer remember the location of its water bowl, withdraw from people or become excessively attached, bark or howl for no apparent reason, and either sleep less or wander restlessly during the night.

Owners can use the acronym DISHA(A) to remember the signs: disorientation in familiar surroundings, changes in interactions, sleep–wake cycle changes, house-soiling, and changes in activity levels. Aggression and anxiety are sometimes included as the additional A's.

Identifying these changes early is important, as cognitive deterioration in pets may progress over just a few months.

Although there is no cure for 'doggy dementia', researchers are testing treatments that could enhance both the quality and duration of life for older dogs.

"Unfortunately, when clinical and behavioral signs become so severe, it is too late: severe clinical manifestations are strictly related to severe neurodegeneration, which is a progressive and irreversible condition," researchers wrote in a review on CSD, published earlier this year.

"This kind of situation leads to owners' irritability and frustration, all elements which contribute to aggravate the relationship with their dogs, without considering that all these things also affect the animals' welfare."

Managing canine cognitive dysfunction symptoms

Measures owners may take to safeguard their dogs include restricting access to hazardous parts of the home, such as staircases, taking more walks to limit accidents indoors, and using medicines such as melatonin.

In the US, selegiline is frequently recommended for dogs diagnosed with age-related cognitive decline, though its effectiveness remains uncertain.

Selegiline is currently the only medicine approved by the US Food and Drug Administration (FDA) to treat CDS. In people, however, the drug has been judged ineffective as a dementia treatment.

With medication producing limited success, researchers at the University of Adelaide in Australia are examining whether tailored training activities can boost cognition in older dogs with CCD.

"Some studies suggest up to 60 percent of senior dogs, mostly over the age of 11, are affected by doggy dementia," University of Adelaide veterinarian Tracey Taylor said in 2024.

"Often owners think their dog is just slowing down, but symptoms such as getting lost at home, changing interactions towards other dogs or humans, and vacant staring can all be signs of CCD."

CDS is also referred to as canine cognitive dysfunction (CCD). Depending on the region, a dog may receive an official CCD diagnosis if it fulfils established scale criteria, including the Canine Dementia Scale (CADES), the Canine Cognitive Assessment Scale (CCAS) or the Canine Cognitive Dysfunction Rating Scale (CCDR).

Yet researchers are still determining the best method for diagnosing the condition, because there is no standardised test or dependable biomarker.

A recent study involving 70 dogs aged seven years or over used the CADES diagnosis. It found that nearly 66 percent of the dogs displayed cognitive dysfunction, while 11 percent had severe dysfunction.

Whether these figures also apply to the other scales used to assess CCD is unknown.

At present, the only definitive way to establish whether a dog had CCD is through examination of its brain after death.

Canine dementia and Alzheimer's disease research

Notably, the brains of dogs that died with CCD contain many of the same markers found in human brains affected by Alzheimer's disease, including protein tangles and an accumulation of amyloid plaques.

That similarity makes pet dogs compelling animal models for studying processes that occur in human brains.

In a perspective paper released in September 2025, US neuroscientists argued that dogs, unlike rodents, offer a valuable dementia model because they share human environments and the risk factors that come with them.

Several of these researchers are involved with the Dog Aging Project at the University of Washington, which aims both to extend pets' lifespans and to improve human health.

They write: "The companion dog provides a disease model that contrasts with animal models living in highly regulated, unnatural domains such as laboratories or kennels."

"If CCD can serve as a large animal disease model for AD in humans," the researchers conclude, "the translational power of future [canine] studies could significantly advance human medicine."

More research into canine dementia could benefit both people and their pets.