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Which Dogs Are Most Likely to Show Mental Decline with Age?

A number of factors beside age can contribute to a dog's loss of mental ability.

Key points

  • A study of more than 15,000 dogs looked at the factors which predict reduction in mental abilities in aging canines
  • When controlling for all other characteristics, the odds of Canine Cognitive Dysfunction increased 52% with each additional year of age.
  • A dog's breed predicts its susceptibility to Canine Cognitive Dysfunction with terriers, toys, and non-sporting dogs being the most vulnerable.
  • Dogs with a low-activity lifestyle are more than six times as likely to show declines in mental ability with age than more active cohorts.
Jackal of all trades licensed CC BY-NC-SA 2.0
Old dog
Source: Jackal of all trades licensed CC BY-NC-SA 2.0

Just as in the case of humans, mental abilities and cognitive functions grow weaker in aging dogs. The principal signs of this mental decline involve memory loss and difficulty learning; however these symptoms can also include a loss of the spatial awareness needed to find a way through the environment, lower degrees of social interaction, poor recognition of previously familiar others, and disrupted sleep patterns. In humans the most severe form of these deficits shows up as Alzheimer's disease. The canine equivalent is called Canine Cognitive Dysfunction or CCD. At the neurological level the similarities between Alzheimer's disease and CCD are quite marked, with both showing changes in the brain involving tangled clumps of neural tissue known as beta-amyloid plaques.

A New Study of Canine Cognitive Dysfunction

The effect of CCD on the quality of a dog's life and its relationship with its owner is as devastating as the effects of Alzheimer's disease on the quality of human life and family relationships. There have been a number of studies which have looked at CCD, but most have been limited in size, so that broad conclusions, such as determining which dogs are most likely to come down with the problem, could only be tentatively made. However a new study by Sarah Yarborough of the University of Washington has provided some answers indicating which dogs are most susceptible to the mental decline associated with CCD.

This study is huge, comprising 15,019 dogs. The data were obtained from the National Institute on Aging nationwide longitudinal study on canine aging and mortality. The Dog Aging Project was started in 2018. The study included administration of a number of surveys including the Health and Life Experience Survey, which gathers a lot of health data and includes sections on dog and owner household demographic characteristics, and the dog's physical activity, environment, behavior, diet, medications and preventatives, and health status. In addition, participants were given the Canine Social and Learned Behavior Survey which is used to determine evidence concerning the mental decline in dogs associated with CCD. Scores for this survey were split into two groups; dogs with a score at or above 50 were classified as having Canine Cognitive Dysfunction.

CCD is a disease of older dogs, so it is not surprising that age is an important factor in increasing the likelihood of its appearance. The increasing risk, however, is quite large. When controlling for all other characteristics, the odds of CCD increased 52% with each additional year of age. However, a number of factors play a role in susceptibility.

It's Not All a Matter of Age

While this study notes that a poor health history, including a number of different diseases and conditions, can contribute to the risk of CCD, each to a small amount, two conditions, both involving sensory abilities, seem to be highly significant. At any given age, dogs that have a history of neurological eye or ear disorders were found to be approximately twice as likely to be classified as having CCD. Similar findings have been found in humans, since individuals with marked hearing loss or diminished visual ability have been shown to be more likely to be diagnosed with Alzheimer's disease.

Although sex did not have much of an effect, sexual status did. When a comparison was made between dogs that were spayed or neutered versus those which were sexually intact it was found that the intact dogs were 64% less likely to be classified as having CCD.

Breed Matters

When the participant dogs were divided by breed, it was found that breed group did make a difference. Using American Kennel Club group designations, those dogs classified as terriers, toys, or in the non-sporting group were more than three times as likely to be diagnosed with Canine Cognitive Dysfunction compared to the other breed groupings.

Something You Can Do

Although nothing can be done to change a dog's breed or its susceptibility to sensory neurological disease, one finding provided a hopeful note since it involved something that the dog's owner has a good deal of control over: Among dogs of the same age, health status, breed type, and sterilization status, the odds of showing Canine Cognitive Dysfunction were a startling 6.47 times higher in dogs that were not active, compared to those who were very active.

So if you want to do something to stave off the mental decline associated with aging, the obvious recommendation from this study is to keep your dogs moving and well-exercised.

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Sarah Yarborough (2021). Evaluation of Cognitive Function in the Dog Aging Project: Association with Baseline Canine Characteristics. University of Washington: Thesis submitted for the degree of Master of Public Health.