Summary: Owning a dog was associated with a 33% lower risk of death for heart attack survivors who lived alone, and a 27% reduced risk for those who suffered a stroke, compared to those who did not own a pet. Additionally, dog ownership was linked to a 24% reduced risk of all-cause mortality and a 31% reduced risk of death by heart attack or stroke.
Source: American Heart Association
Dog ownership may be associated with longer life and better cardiovascular outcomes, especially for heart attack and stroke survivors who live alone, according to a new study and a separate meta-analysis published in Circulation: Cardiovascular Quality and Outcomes.
“The findings in these two well-done studies and analyses build upon prior studies and the conclusions of the 2013 AHA Scientific Statement ‘Pet Ownership and Cardiovascular Risk’ that dog ownership is associated with reductions in factors that contribute to cardiac risk and to cardiovascular events,” said Glenn N. Levine, M.D., chair of the writing group of the American Heart Association’s scientific statement on pet ownership. “Further, these two studies provide good, quality data indicating dog ownership is associated with reduced cardiac and all-cause mortality. While these non-randomized studies cannot ‘prove’ that adopting or owning a dog directly leads to reduced mortality, these robust findings are certainly at least suggestive of this.”
Given previous research demonstrating how social isolation and lack of physical activity can negatively impact patients, researchers in both the study and meta-analysis sought to determine how dog ownership affected health outcomes. Prior studies have shown that dog ownership alleviates social isolation, improves physical activity and even lowers blood pressure—leading researchers to believe dog owners could potentially have better cardiovascular outcomes compared to non-owners.
Dog ownership and survival after a major cardiovascular event—a registry-based, prospective study
Researchers in this study compared the health outcomes of dog owners and non-owners after a heart attack or stroke using health data provided by the Swedish National Patient Register. Patients studied were Swedish residents ages 40-85 who experienced a heart attack or ischemic stroke from 2001-2012.
Compared to people who did not own a dog, researchers found that for dog owners:
- The risk of death for heart attack patients living alone after hospitalization was 33% lower, and 15% lower for those living with a partner or child.
- The risk of death for stroke patients living alone after hospitalization was 27% lower and 12% lower for those living with a partner or child.
In the study, nearly 182,000 people were recorded to have had a heart attack, with almost 6% being dog owners, and nearly 155,000 people were recorded to have had an ischemic stroke, with almost 5% being dog owners. Dog ownership was confirmed by data from the Swedish Board of Agriculture (registration of dog ownership has been mandatory since 2001) and the Swedish Kennel Club (all pedigree dogs have been registered since 1889).
The lower risk of death associated with dog ownership could be explained by an increase in physical activity and the decreased depression and loneliness, both of which have been connected to dog ownership in previous studies.
“We know that social isolation is a strong risk factor for worse health outcomes and premature death. Previous studies have indicated that dog owners experience less social isolation and have more interaction with other people,” said Tove Fall, D. V. M., professor at Uppsala University in Sweden.
“Furthermore, keeping a dog is a good motivation for physical activity, which is an important factor in rehabilitation and mental health.”
While this study draws from a large sample, potential misclassifications of dog ownership in couples living together, death of a dog and change of ownership could have affected the outcomes of the study.
“The results of this study suggest positive effects of dog ownership for patients who have experienced a heart attack or stroke. However, more research is needed to confirm a causal relationship and giving recommendations about prescribing dogs for prevention. Moreover, from an animal welfare perspective, dogs should only be acquired by people who feel they have the capacity and knowledge to give the pet a good life.”
Co-authors of the study are Mwenya Mubanga, M.D., M.P.H.; Liisa Byberg, Ph.D.; Agneta Egenvall, V.M.D., Ph.D.; Erik Ingelsson, MD, Ph.D. and Tove Fall, V.M.D., Ph.D.
Funding: Agria Research Foundation and the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS), grant number 2013-1673 funded the study.
Dog Ownership and Survival: A Systematic Review and Meta-Analysis
Researchers reviewed patient data of over 3.8 million people taken from 10 separate studies for a composite meta-analysis study. Of the 10 studies reviewed, nine included comparison of all-cause mortality outcomes for dog owners and non-owners, and four compared cardiovascular outcomes for dog owners and non-owners.
Researchers found that compared to non-owners, dog owners experienced a:
- 24% reduced risk of all-cause mortality;
- 65% reduced risk of mortality after heart attack; and
- 31% reduced risk of mortality due to cardiovascular-related issues.
“Having a dog was associated with increased physical exercise, lower blood pressure levels and better cholesterol profile in previous reports,” said Caroline Kramer, M.D. Ph.D., Assistant Professor of Medicine at the University of Toronto and an Endocrinologist and Clinician scientist at Leadership Sinai Centre for Diabetes at Mount Sinai Hospital, part of Sinai Health System. “As such, the findings that people who owned dogs lived longer and their risk for cardiovascular death was also lower are somewhat expected.”
According to two new studies, owning a dog is associated with longer lives and better cardiovascular outcomes. Credit: American Heart Association.
Studies deemed eligible for analysis included those conducted among adults age 18 or older, original data from an original prospective study, evaluated dog ownership at the beginning of the study and reported all-cause or cardiovascular mortality of patients. Studies were excluded if they were retrospective, did not provide an absolute number of events that occurred and reported non-fatal cardiovascular events.
“Our findings suggest that having a dog is associated with longer life. Our analyses did not account for confounders such as better fitness or an overall healthier lifestyle that could be associated with dog ownership. The results, however, were very positive,” said Dr. Kramer. “The next step on this topic would be an interventional study to evaluate cardiovascular outcomes after adopting a dog and the social and psychological benefits of dog ownership. As a dog owner myself, I can say that adopting Romeo (the author’s miniature Schnauzer) has increased my steps and physical activity each day, and he has filled my daily routine with joy and unconditional love.”
Co-authors of the meta-analysis are Caroline K. Kramer, M.D., Ph.D., Sadia Mehmood, B.S., and Renée S. Suen. Author disclosures are in the manuscripts.
Funding: Intramural funds from Mount Sinai Hospital funded the meta-analysis.
American Heart Association
William Westmoreland – American Heart Association
The image is in the public domain.
Original Research: Open access
“Dog Ownership and Survival After a Major Cardiovascular Event:
A Register-Based Prospective Study”. Mwenya Mubanga, Liisa Byberg, Agneta Egenvall, Erik Ingelsson, Tove Fall.
Circulation: Cardiovascular Quality and Outcomes doi:10.1161/CIRCOUTCOMES.118.005342.
“Dog Ownership and Survival: A Systematic Review and Meta-Analysis”. Caroline K. Kramer, Sadia Mehmood, Renée S. Suen.
Circulation: Cardiovascular Quality and Outcomes doi:10.1161/CIRCOUTCOMES.119.005554.
Dog Ownership and Survival After a Major Cardiovascular: Event
A Register-Based Prospective Study
Dog ownership is associated with increased physical activity levels and increased social support, both of which could improve the outcome after a major cardiovascular event. Dog ownership may be particularly important in single-occupancy households where ownership provides substitutive companionship and motivation for physical activity.
Methods and Results:
We used the Swedish National Patient Register to identify all patients aged 40 to 85 presenting with an acute myocardial infarction (n=181 696; 5.7% dog ownership) or ischemic stroke (n=154 617; 4.8% dog ownership) between January 1, 2001 and December 31, 2012. Individual information was linked across registers for cause of death, sociodemographic, and dog ownership data. We evaluated all-cause mortality and risk of recurrent hospitalization for the same cause until December 31, 2012. Models were adjusted for socioeconomic, health, and demographic factors at study inclusion such as age, marital status, the presence of children in the home, area of residence, and income, as well as all registered comorbidities and hospitalization for cardiovascular disease in the past 5 years. Dog owners had a lower risk of death after hospitalization for acute myocardial infarction during the full follow-up period of 804 137 person-years, with an adjusted hazard ratio (HR) of 0.67 (95% CI, 0.61 to 0.75) for those who lived alone, and HR of 0.85 (95% CI, 0.80 to 0.90) for those living with a partner or a child. Similarly, after an ischemic stroke, dog owners were at lower risk of death during the full follow-up of 638 219 person-years adjusted HR of 0.73 (95% CI, 0.66 to 0.80) for those who lived alone and HR of 0.88 (95% CI, 0.83 to 0.93) for those living with a partner or a child. We further found an association of dog ownership with reduced risk of hospitalization for recurrent myocardial infarction (HR, 0.93; 95% CI, 0.87 to 0.99).
We found evidence of an association of dog ownership with a better outcome after a major cardiovascular event. Although our models are adjusted for many potential confounders, there are also unmeasured confounders such as smoking that prevent us from drawing conclusions regarding a possible causal effect.
Dog Ownership and Survival: A Systematic Review and Meta-Analysis
Dog ownership has been associated with decreased cardiovascular risk. Recent reports have suggested an association of dog companionship with lower blood pressure levels, improved lipid profile, and diminished sympathetic responses to stress. However, it is unclear if dog ownership is associated with improved survival as previous studies have yielded inconsistent results. Thus, we performed a systematic review and meta-analysis to evaluate the association of dog ownership with all-cause mortality, with and without prior cardiovascular disease, and cardiovascular mortality.
Methods and Results:
Studies published between 1950 and May 24, 2019 were identified by searching Embase and PubMed. Observational studies that evaluated baseline dog ownership and subsequent all-cause mortality or cardiovascular mortality. Two independent reviewers extracted the data. We assessed pooled data using random-effects model. A possible limitation was that the analyses were not adjusted for confounders. Ten studies were included yielding data from 3 837 005 participants (530 515 events; mean follow-up 10.1 years). Dog ownership was associated with a 24% risk reduction for all-cause mortality as compared to nonownership (relative risk, 0.76; 95% CI, 0.67–0.86) with 6 studies demonstrating significant reduction in the risk of death. Notably, in individuals with prior coronary events, living in a home with a dog was associated with an even more pronounced risk reduction for all-cause mortality (relative risk, 0.35; 95% CI, 0.17–0.69; I2, 0%). Moreover, when we restricted the analyses to studies evaluating cardiovascular mortality, dog ownership conferred a 31% risk reduction for cardiovascular death (relative risk, 0.69; 95% CI, 0.67–0.71; I2, 5.1%).
Dog ownership is associated with lower risk of death over the long term, which is possibly driven by a reduction in cardiovascular mortality.