Source: Licensed from Vital Imagery
For over 40 years research has been accumulating which shows that people who own dogs also seem to benefit from improved health both physically and psychologically. Of particular importance is the fact that dogs seem to be good for your heart (physically as well as emotionally). In fact in 2013 a special report was issued by the American Heart Association which concluded that dog ownership is most likely associated with decreased cardiovascular disease risk. However, even if you do have a heart attack of some sort, one of the encouraging findings is that dog ownership can still help improve your survival prospects.
I can still remember when, in 1980, I was startled to read a research report of a study done by Erika Friedman (then at Brooklyn College) and a team of researchers from the University of Pennsylvania. The study looked at a group of patients who had been admitted to hospital because of acute severe heart problems (myocardial infarction or angina pectoris). A lot of personal information was gathered about these patients including whether or not they owned a pet (in most cases a dog). When the research team conducted a one-year follow-up they found that the pet owners were nearly five times more likely to still be alive than those who did not own pets. Only 6% of the pet owners had died during that period as compared to 29% of the non-pet owners (meaning a 23% improvement in survival). This study generated a lot of controversy, partly because the effects appeared to be so large. Other researchers worried about the sample size being too small, and they had concerns about how patients were selected and so forth. Since its initial publication a number of additional studies have been conducted and virtually all of them have shown the positive effect that dogs have on heart health. Unfortunately, because of the difficulty associated with obtaining patient data and the fact that the follow up times must extend at least a year (better if longer than that) the experimental groups have always been small causing some scientists to still have some doubts about how reliable these results were. Some new data has now become available using some very large databases and it seems to confirm these earlier results. These findings show that even if you have had a major cardiac event, your survival is greatly improved if you own a dog.
This new data comes from Mwenya Mubanga of the Department of Medical Sciences at Uppsala University in Sweden and it forms part of her doctoral thesis research. The size and scope of the data collection is larger than any that has ever been published before concerning this issue. Mubanga and her co-investigators took advantage of the fact that everyone in Sweden must carry a unique personal identification number which allows their health data to be tracked. Thus for every member of the Swedish population each person’s hospital and medical records are entered into a set of national registries. There is also a national registry of deaths which includes all of the causes associated with each death. In this study the researchers used the Swedish National Patient Register, to find all patients who were hospitalized for heart problems — specifically for their first ever myocardial infarction (which resulted in a total of 181,696 patients) or their first ischemic stroke (a total of 157,617 patients). The data collection included hospitalizations after January 1, 2001. This starting date was chosen because it was also the date that it became a legal requirement for every dog in Sweden to have a unique identifier in the form of an ear tattoo or a microchip to allow each dog’s information to be entered into a set of registries linking the pet with its owner. From that starting date each patient diagnosed with one of these forms of heart disease was tracked over a 12 year period. Given the large number of people monitored (over 300,000) and the length of time that the individuals were followed after their initial hospitalization (12 years) it seems likely that any conclusions that were reached would be very stable and reliable.
What these new results show is quite remarkable. If we look at the patients who suffered from a myocardial infarction the investigators found that owning a dog at the time you were originally hospitalized is associated with a 24% reduction in the overall likelihood that you will end up dead compared with individuals who did not own a dog (over the 12 years that the patients were followed). When we look at the patients hospitalized for ischemic strokes there is a 20% reduction in the likelihood that you will die if you own a dog, as compared to individuals who do not. As a scientist it is very comforting to find that these results are very similar to those found in Friedman’s original study. It suggests that we are looking at a robust and reliable relationship.
An interesting additional finding is that the beneficial effects of canine companionship are actually considerably larger if you normally live alone. An individual living alone except for the company of a dog is 35% less likely to die of a myocardial infarction and 28% less likely to die of an ischemic stroke than an individual who is living alone without the social presence of a pet dog.
It is this finding which caused Mubanga to suggest that one of the ways in which a dog improves your chance of survival might be by providing a source of social interaction and thus preventing feelings of loneliness. She notes that it is well established that loneliness is itself an independent risk factor associated with premature death because of causes like hypertension and coronary heart disease. This is probably due to the fact that living without any day to day social relations or interplay leads to stress and depression which are known contributors to heart problems. The presence of a dog in your household has the same protective value as living with other human individuals.
So the conclusion that could probably be drawn from this new data is that even if you have been diagnosed with coronary problems it might be a good idea to think about getting a dog as a pet if you do not have one at the moment. The evidence is that having a canine companion might very well extend your life even if your heart disease has already caused you to be hospitalized at least once.
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