If dogs no longer recognize people who are actually familiar to them, a disease similar to Alzheimer’s can be the cause. Because pets can also suffer from mental deterioration. And the older they get, the higher the risk.
In old age, dogs not only deteriorate physically, but also mental performance dwindles. From a certain phase of life, the risk of dementia increases significantly from year to year, as researchers report in the journal “Scientific Reports”. Experts speak of Canine Cognitive Dysfunction Syndrome (CCD). According to the study, the risk of developing it is around six and a half times higher in less active animals than in very active ones. However, further analyzes are needed to clarify cause and effect for this connection.
As in humans, the cognitive functions of pets such as dogs and cats also decrease with age. CCD is similar to the clinical picture and course of Alzheimer’s disease in humans. Affected dogs show symptoms such as memory lapses, loss of spatial orientation, altered social behavior and sleep disorders. Since larger dogs have a lower average life expectancy than small breeds and therefore age earlier, they are also more likely to develop CCD symptoms earlier.
In dogs over ten years old, the risk of CCD increases by more than 50 percent with every additional year of life, as the scientists working with Sarah Yarborough from the University of Washington in Seattle calculated. They used data from more than 15,000 pet dogs from the Dog Aging Project, a US study of animal aging. The owners completed questionnaires about health and physical activity, as well as a test for CCD, which asks, among other things, whether the dog still recognizes familiar people. The life expectancy of the dogs was divided into quarters.
Almost a fifth of the dogs recorded were in the last quarter of their lives. A total of 1.4 percent of the animals were classified as suffering from CCD. Around a quarter of around 17-year-old animals were affected, and around half of around 19-year-old animals. However, the researchers caution that the classification was based solely on the questionnaires and not on veterinary diagnosis and was therefore prone to various confounding factors. Previous estimates of CCD rates were sometimes much higher: 28 percent in 11- to 12-year-old dogs and 68 percent in 15- to 16-year-old dogs.
According to the current analysis, less active dogs were much more frequently affected by CCD than active ones. However, the researchers point out that it still needs to be checked what is cause and effect in which parts: Cognitive decline can also lead to less activity, i.e. it can be the reason and not the result. However, numerous observational studies on humans have consistently shown that more exercise is associated with less Alzheimer’s. Exercise leads to a reduction in inflammatory substances in the brain that contribute to nerve cell death and an increase in neuronal plasticity – such mechanisms may also explain the lower likelihood of CCD in more active dogs.
The influence of factors such as breed, gender and certain diseases was also examined, according to which dogs with an eye, ear or neurological disease over the course of their lives had a higher probability of developing CCD. The data could help veterinarians decide when a dog should be screened for CCD when symptoms are present, the research team said.
