Pet Ownership and Cardiovascular Risk: A Scientific Statement From the American Heart Association
The following are 10 points to remember about this statement on pet ownership and cardiovascular (CV) risk:
1. Numerous studies have explored the relationship between pet (primarily dog or cat) ownership and CV disease (CVD), with many reporting beneficial effects, including increased physical activity, favorable lipid profiles, lower systemic blood pressure, improved autonomic tone, diminished sympathetic responses to stress, and improved survival after an acute coronary syndrome. Accordingly, the potential CV of pet ownership have received considerable lay press and medical media coverage and attention from the Centers for Disease Control and Prevention, and have been the focus of a meeting sponsored by the National Institutes of Health. The purpose of this American Heart Association Scientific Statement was to critically assess the data regarding the influence of pet ownership on the presence and reduction of CVD risk factors and CVD risk.
2. Some, but not all, studies of pet ownership and systemic blood pressure have found an association between pet ownership and lower blood pressure. An Australian study of 5,741 participants attending a free screening clinic found that pet owners had significantly lower systolic blood pressures than pet nonowners despite similar body mass index (BMI) and socioeconomic profiles. The only randomized data on pet ownership and blood pressure come from a presented, but unpublished study of 30 participants with borderline hypertension who were randomized either to adopt a dog from a shelter or to defer adoption of a dog. Ambulatory resting systolic blood pressure was similar in both groups at baseline (before dog adoption or deferred adoption). Ambulatory blood pressure monitoring 2 and 5 months after dog adoption demonstrated significantly (p < 0.001) lower systolic blood pressures in the dog-adoption group than in the deferred adoption group.
3. Data are minimal regarding the association of pet ownership and lipid levels. In a study of 5,741 participants attending a free screening clinic, male (but not female) dog owners had significantly but clinically modestly lower total cholesterol (201 vs. 206 mg/dl; p = 0.02) and triglyceride (108 vs. 125 mg/dl; p = 0.01) levels than nonowners of dogs. In a small (n = 32) cross-sectional study of adults ≥60 years of age, pet owners had significantly lower triglyceride levels than pet nonowners (109 vs. 192 mg/dl; p < 0.01). In a cross-sectional online survey (n = 916), dog nonowners were more likely to report elevated serum cholesterol levels and diabetes mellitus than dog owners who regularly walked their dogs. These findings persisted after controlling for owner’s age and intensity of physical activity, but not after also controlling for BMI. In addition, tobacco use was more common among dog nonowners than dog owners.
4. Dogs appear most likely to positively influence the level of human physical activity. Cross-sectional studies show that dog owners engage in more physical activity and walking, and are more likely to achieve the recommended level of physical activity than nonowners of dogs. Dog owners who walk their dogs are more likely to achieve the recommended level of physical activity than dog owners who do not walk their dogs. Unfortunately, a significant proportion of dog owners do not regularly walk their dogs. No significant associations have been reported between physical activity and cat or other types of pet ownership.
5. Participation in physical activity jointly by pets and humans is one mechanism whereby pet ownership may reduce obesity. The other important role that pets play in human health is social support, which is one of the most powerful predictors of adoption and maintenance of behavior change, including weight loss. Companion animals may strengthen engagement in a weight loss program by providing encouragement, and motivation and reducing perceived barriers that hinder exercise. One study (the People and Pets Exercising Together [PPET] Study) assessed whether people walking with their dogs would lose more weight after 1 year compared to people walking alone. Thirty-six pairs of overweight or obese people with an obese pet and 56 overweight or obese people without pets participated in a 1-year prospective, controlled weight loss study in which people received dietary and physical activity counseling and dogs were fed a calorie-controlled prescription diet. Both people and their pets successfully lost weight; however, obese pet owners had similar weight loss as those without pets (4.7% vs. 5.2%, respectively; p = NS).
6. A positive or beneficial relationship between pet ownership and autonomic function or CV reactivity to stress has been reported in most, but not all published studies. CV reactivity to stress (i.e., mental arithmetic and cold pressor) was assessed in 240 couples, half of whom owned a cat or dog. People with pets had significantly lower resting baseline heart rates and blood pressure, significantly smaller increases in heart rate and blood pressure in response to stress, and faster recovery of these parameters to baseline after cessation of stress. Reactivity to stress was lowest and recovery fastest in couples tested when their pet was present. Although most studies of autonomic and CV reactivity involved dogs or cats, several studies demonstrated beneficial effects on these parameters associated with goat, fish, chimpanzee, and snake ownership. One experiment even demonstrated a benefit on CV stress responses with ‘virtual’ animals, which were presented in the form of video recordings.
7. There are scant data on pet ownership and survival in people without established CVD. Analysis of data from a large national health survey did not find a survival advantage associated with pet ownership. Likewise, analysis of data from the NHANES II, a longitudinal cohort study, did not find that pet ownership was associated with reduced overall mortality.
8. Cardioprotective benefits associated with pet may be observed in patients with established CVD. In a substudy of the Cardiac Arrhythmia Suppression Trial (CAST), 1-year survival data were assessed in 369 study participants on the basis of whether or not the participant owned a pet. Overall, pet ownership of any kind tended to be independently associated with survival (p = 0.085). Dog ownership was strongly associated with decreased mortality, with the likelihood of mortality being 4.05 times greater for dog nonowners than for dog owners (p < 0.05); the benefit of dog ownership on survival was independent of physiological measures or the severity of CVD. Cat ownership was not found to be associated with decreased mortality or cardiac-related rehospitalization. A post-hoc analysis of survivors of myocardial infarction who were followed up in the Psychosocial Responses in the Home Automated External Defibrillator Trial (PR-HAT) found that lack of pet ownership was a significant (p = 0.036) predictor of mortality. In contrast to the findings in the above studies, a study of 412 patients with acute coronary syndrome found that the 1-year risk of readmission or cardiac death was not statistically different between dog owners and nonowners (odds ratio, 1.59; 95% confidence interval, 0.759-3.321; p = 0.22), and was greater in cat owners than in nonowners (odds ratio, 3.22; 95% confidence interval, 1.44-7.19; p = 0.004).
9. The writing group’s conclusions and recommendations include the following: pet ownership, particularly dog ownership, is probably associated with decreased CVD risk (Level of Evidence B), and pet ownership, particularly dog ownership, may have some causal role in reducing CVD risk (Level of Evidence B).
10. Recommendations include pet ownership, particularly dog ownership, may be reasonable for reduction in CVD risk (Class IIb; Level of Evidence B), and pet adoption, rescue, or purchase should not be done for the primary purpose of reducing CVD risk (Class III; Level of Evidence C).
This statement provides an interesting summary of current literature on pet ownership and CVD risk, and provides well-written highlights of the CV benefits of pet ownership.
Keywords: Acute Coronary Syndrome, Stroke, Weight Loss, Human-Animal Bond, Body Weight, Risk Factors, Autonomic Nervous System, Centers for Disease Control and Prevention, U.S., Cholesterol, Walking, Body Mass Index, Weight Reduction Programs, Australia, Blood Pressure Monitoring, Ambulatory, Cardiovascular Diseases, National Institutes of Health (U.S.), Obesity, Triglycerides, Tobacco Use Disorder, Hypertension, United States, Diabetes Mellitus
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