I will take any excuse I can get to justify getting a dog. They’re cute and loving, and they just make me want to smile. For me this is validation enough. However, a recent article in the New York Times stated that “Dog Owners Live Longer” too! Game changer.
The New York Times references a study from Scientific Reports in claiming that dog ownership is “associated with a 20 percent lower risk of all-cause death and a 23 percent lower risk of death from cardiovascular disease”. Furthermore the article claimed that the association was stronger among specific breeds of dogs: labradors and pointers. I took a look at the study to learn more.
The observational study took place in Sweden using the Register of the Total Population, a national registry containing information for all Swedish citizens and residents. The study focused on the population most at risk of cardiovascular disease (CVD) and dog ownership by limiting the population to individuals between the ages of 40 and 80. Data regarding dog ownership was also collected through a nationally required dog registration, allowing individuals and dog ownership to be properly linked. Data was also collected on Swedish twins but this sample size was much smaller; we will focus on the nationwide study.
Scientists plugged all this information into a data base, creating two very important outcomes: crude and adjusted hazard ratios. The crude ratio was only adjusted for sex while the adjusted ration accounted for differences in “sex, marital status, presence of children in the home, population density, area of residence, region of birth, income and latitude”. Among the most shocking results were the adjusted hazard ratios of 0.77 for CVD mortality and 0.80 for all-cause mortality – a 23% and and 20% decrease, respectively.
These are pretty significant numbers – especially considering the large sample size, confidence intervals, and minimal sampling variation. The conclusion seems to be a no brainer, but we have to be mindful of what the conclusion is – correlation not causation. Of course dog ownership can encourage individuals to be more active. Dogs are kind of like the postal service; neither snow nor rain nor heat nor gloom of night stays these dogs from needing their walks. However, one cannot attribute this study’s results to this reason.
Maybe another factor causes this link between lowered CVD deaths and dog ownership. Perhaps all dog owners – especially those of pointer breeds – have similar characteristics. Perhaps the responsibility necessary for dog ownership corresponds to a responsibility for one’s diet and health. Perhaps a large number of pointer owners are outdoor enthusiasts who maintain non-dog related physical activity. In fact, the study even lists these possible confounding variables in its conclusion.
Readers of the New York Times may see this article and view dog ownership as a ticket to a longer life. After all, it is a good bet. Something about dog ownership creates a shift in risk of death. But it’s not a guarantee. Owning a dog does not assure that you inherit the characteristics of most dog owners, of which one or some characteristics likely caused the correlation in the first place. Like most doctors will tell you the best mean for a long, healthy life is to eat right and exercise. Although exercise is a lot more fun with some floppy ears and a wagging tail by your side…