Doggy Dementia: Signs, Diagnosis and Research in Senior Dogs

Our pets are living longer than ever, but ageing also raises their likelihood of cognitive decline resembling human dementia.

In dogs, this condition is known as cognitive dysfunction syndrome (CDS). The illness is subtle and gradually progressive, often developing so slowly that even highly attentive owners may not spot 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.

Signs of cognitive dysfunction syndrome in dogs

Neurological symptoms are "very unspecific", yet can include disorientation, changed social behaviour, house-soiling, anxiety and disruptions to the sleep–wake cycle. A dog may no longer remember the location of its water bowl, withdraw from people or become excessively dependent, bark or howl for no apparent reason, and either sleep less or wander restlessly overnight.

Owners can use the acronym DISHA(A) to recall the warning signs. It refers to disorientation in familiar surroundings, changes in interactions, altered sleep–wake cycles, house-soiling, and shifts in activity levels. Aggression and anxiety are sometimes included as additional A's.

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

Although there is no cure for 'doggy dementia', treatments are under investigation 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."

Measures that owners might use to keep their dogs safe include restricting access to hazardous parts of the home, such as stairs, taking more walks to limit accidents indoors, and using medicines including melatonin.

In the US, selegiline is frequently recommended for dogs diagnosed with cognitive decline linked to ageing, though its efficacy remains uncertain.

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

Research into canine cognitive dysfunction (CCD)

Because drug treatments have had limited success, University of Adelaide researchers in Australia are examining whether tailored training activities can boost cognition in senior 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 another name for canine cognitive dysfunction (CCD). Depending on the location, a dog can receive an official CCD diagnosis if it satisfies recognised scoring systems, such as the Canine Dementia Scale (CADES), the Canine Cognitive Assessment Scale (CCAS) or the Canine Cognitive Dysfunction Rating Scale (CCDR).

However, researchers are still determining the most effective way to diagnose the condition, since there is no standardised test or dependable biomarker.

A recent study involving 70 dogs aged seven or older used the CADES diagnostic method. It reported that almost 66 percent of the dogs displayed cognitive dysfunction, while 11 percent had severe dysfunction.

Whether these proportions apply to the other scales used to evaluate CCD is unknown.

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

What canine dementia reveals about Alzheimer's disease

Notably, dogs that died with CCD have brains showing many of the same features 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 understanding processes occurring in the human brain.

In a perspective paper released in September 2025, US neuroscientists argued that dogs, unlike rodents, offer a valuable dementia model because they live in the human environment and encounter its related risk factors.

Several of the authors are involved in the Dog Aging Project at the University of Washington, an initiative intended both to extend pets' lifespans and to benefit 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 help both people and their pets.