Pet Ownership and the Risk of Arterial Hypertension and Cardiovascular Disease

1Faculty of Medical Sciences in Katowice, Medical University of Silesia, Katowice, Poland

2Club of Young Hypertensiologists, Polish Society of Hypertension, Gdańsk, Poland

3Department of Medicine, School of Medicine, University of Alabama at Brimingham, Brimingham, AL USA

4Chair and Department of Hypertension and Diabetology, Medical University of Gdańsk, Dębinki 7, 80-952 Gdańsk, Poland

Hypertension prevention and cardiovascular risk reduction are cornerstones in the prevention and treatment of cardiovascular diseases. Potential applicability of nontraditional cardiovascular risk reduction methods, such as pet ownership, raises a growing interest.

Studies show that having pets may reduce the risk of death from any cause, particularly from cardiovascular causes. Furthermore, results of some studies indicate that having pets may reduce the risk of developing hypertension and improve blood pressure control in patients with established hypertension. In addition, there is evidence that having pets may improve the prognosis of patients after myocardial infarction and stroke. One of the most important cardioprotective mechanisms of pet ownership is reduction in activity of the sympathetic nervous system.

Pet ownership has a positive effect on the cardiovascular system, likely related to antihypertensive and cardioprotective mechanisms.

Pharmacotherapy and lifestyle modifications are the cornerstones in the prevention and treatment of cardiovascular diseases (CVDs). The potential applicability of nontraditional CVD risk reduction methods, such as pet ownership, has become an area of growing interest in recent years. Having a pet, especially a dog or a cat, has become increasingly popular worldwide. In 2016, 48 million American households had 77 million dogs, 28% of which were rescued from animal shelters [1]. In Poland, according to a survey conducted by Polish Public Opinion Research Center (TNS OBOP) in 2018, 48% of people owned a pet. The aim of this review is to summarize current evidence regarding the link between pet ownership, hypertension, and CVD risk.

The relationship between pet ownership and mortality risk has been a subject of research since the 1980s. In their recently published meta-analysis of 10 studies with over 3.8 million participants, Kramer et al. showed that ownership of a dog was associated with a 24% reduction in risk of all-cause mortality (relative risk; RR = 0.76; 95% CI: 0.67–0.86) [2••]. An even greater (up to 65%) reduction in risk of all-cause mortality was seen in patients with previous coronary events who lived in a house with dogs (RR = 0.35; 95% CI: 0.17–0.69). In a subanalysis of studies with a follow-up of > 10 years, the beneficial effect of having a dog on the risk of all-cause mortality was sustained over time (RR = 0.73; 95% CI: 0.64–0.84). In particular, people who had a dog had a significantly reduced risk of death from CVD (RR = 0.69; 95% CI: 0.67–0.71) [2••].

These results were not fully confirmed in the meta-analysis published in the same year by Yeh et al. [3••]. The meta-analysis included 12 studies with 488,986 participants and a mean follow-up time of 8.7 ± 6.3 years. It showed that having an animal (cat, dog) was not clearly related to risk of death from CVD cause [significant reduction of 7% (95% CI: 0.86–0.99) only in healthy persons] or risk of CVD [(significant reduction of 29% (95% CI: 0.60–0.84) only in persons with established CVD]. Pet ownership did not influence the risk of all-cause mortality in this study [3••]. In a meta-analysis published in 2020 by Bauman et al., the results of the meta-analysis by Kramer et al. were revised by adjusting for many risk factors that could modify the effects of having a dog. Having a dog significantly reduced the risk of death from any cause by 61% only in people with previous CVD (heart rate (HR) = 0.39; 95% CI: 0.20–0.77) [4••]. The latest meta-analysis of 26 studies by El-Qushayri et al., which took into account multiple risk factors, showed that people who had a home pet had a 19% lower risk of death from CVD (HR = 0.81; 95% CI: 0.68–0.97). A subgroup analysis found that the greatest reduction in the risk of death from CVD occurred in those who owned a cat (HR = 0.79; 95% CI: 0.63–0.99) [5••].

Overall, having a pet was associated with lowering of CVD risk in patients with established CVD but not in healthy subjects [2••, 3••, 4••, 5••]. A summary of the above meta-analyzes is presented in Table ​Table11.

Summary of the results of meta-analyzes assessing the impact of having pets on the risk of death. CV, cardiovascular; CVD, cardiovascular disease; MI, myocardial infarction

Based on the results of the above meta-analyses, it is not possible to conclusively determine whether owning pets is associated with a lower risk of all-cause mortality, but owning pets can reduce the risk of death from CVD causes. Moreover, having pets may reduce risk of CVD events in patients with established CVD [2••, 3••, 4••, 5••].

The effect of pet ownership on blood pressure (BP) is controversial. Results of older observational studies analyzing the link between pet ownership and hypertension are inconclusive [6–8]. After adjusting for age and other confounders, pet ownership was not associated with BP increases or risk of hypertension. Furthermore, a recent National Health and Nutrition Examination Survey demonstrated that even after considering potential confounding factors, having a pet (cat or dog) was an independent predictor of lower hypertension risk (Table ​(Table2)2) [9••]. However, a meta-analysis of 11 studies found that persons with a pet had a 1.7 mmHg (95% CI: − 3.062 to − 0.310 mmHg) lower systolic BP (SBP), a non-significant reduction in diastolic BP (DBP) [mean diastolic BP = − 0.23 (95% CI: − 1.05 to 0.60)], and a significant decrease in HR of 2.3 bpm (95% CI: − 3.074 to − 1.573 bpm) [5••]. The BP lowering effect was especially evident during direct contact with the pet [10], and influenced by the intesity of the owner-pet relationship [11], species of the pet [9••, 12] and breed of dog [13].

The risk of hypertension depending on the type of pet owned. Based on [9••]. OR, odds ratio; 95% CI, 95% confidence interval

A study by Xu et al. assessed the effect of having pets on BP in 9354 children and adolescents aged 5–17 years in China [14•]. Over 1/5 of the participants had current exposures to pets and 10.6% of participants had dogs. Children who had a dog had a significantly lower (32–34%) risk of hypertension. Furthermore, prior exposure to a pet during fetal life significantly reduced the risk of hypertension by 34% (95% CI: 0.45–0.97) in men [14•]. Another study by Xu et al. assessed the effect of having pets on the risk of developing hypertension in children who were exposed toenvironmental tobacco smoke (ETS) [15•]. Those who were not exposed to pets were at increased risk of developing hypertension compared to those exposed to pets, and the protective effect of pet ownership increased with a greater number of pets in the home. Exposure to in utero ETS was associated with hypertension (aOR) = 1.32; 95% CI: 1.13–1.54) only for those children without pet exposure in utero but not for those with pets (aOR = 0.75; 95% CI: 0.49–1.15). Household dog ownership was associated with significantly lower effects of ETS on hypertension and the associations between ETS and pet ownership were more robust for girls than for boys and for younger than older children [15•]. A study by Lawrence et al., which included the same group of children as the studies by Xu et al., assessed the effect of in utero exposure to pets (woman having a pet during pregnancy) on the risk of hypertension from air pollutants later in life [16•]. Children not exposed to home pets had a significantly stronger hypertensive response to air pollution. For example, the highest odds ratios per 30.6 μg/m3 increase in PM10 (inhalable particles, with diameters that are generally 10 μm and smaller) were 1.79 (95% CI: 1.29–2.50) in children without current pet exposure compared to 1.24 (95% CI: 0.85–1.82) in children with current pet exposure. Furthermore, the increases in mean diastolic BP per 46.3 μg/m3 increase in O3 (ozone) were 0.60 mmHg (95% CI: 0.21–0.48 mmHg) in children without pet exposure in utero and 0.34 mmHg (95% CI: 0.21–0.48 mmHg) in those with in utero pet exposure. Thus, in utero exposure to a domestic animal mitigated the negative impact of air pollutants on the risk of developing hypertension later in life [16•].

Based on the available observational and interventional studies, it is not possible to conclusively determine whether having pets reduces BP and the risk of hypertension in the general population. The elderly and children who have a pet appear to benefit most in reducing high BP and the risk of hypertension. Importantly, having pets can alleviate the prohypertensive properties of environmental exposure to tobacco smoke or air pollution.

A study by Allen et al. analyzed the impact of having a pet on BP, HR, and plasma renin activity in 48 patients with hypertension who were exposed to stress (mathematical task) [17]. Participants were divided into two groups. The first received lisinopril (20 mg/day), and the second was given a pet, in addition to lisinopril. Having a pet increased the antihypertensive effect of lisinopril and decreased the HR and plasma renin activity responses to stress (Fig. 1) [17]. This interventional study provided evidence that having a pet may contribute to better BP control in patients with hypertension.

Effect of a home pet on reducing BP in persons with stress-induced BP increases. Based on [17]

Similar results were obtained by Friedmann et al. in an observational study of the effects of owning a dog or cat on BP in 32 people aged 50–83 with SBP in 120–150 mmHg and DBP in 80–100 mmHg or SBP Open in a separate windowFig. 2

Potential mechanisms for the cardiovascular benefit of dog ownership. Based on [1, 32]

Beneficial effects of pet ownership on cardiovascular risk. SBP, systolic blood pressure; MAP, mean arterial pressure; TG, triglycerides. Based on [31]

Some confounding factors may explain the discrepancies in the results of studies analyzing the CV effects of pet ownership. Pet owners tend to be wealthier, better educated, and married [1]. Furthermore, the link between dog ownership and good health may not be causal, as adults with excellent physical health are more likely to adopt a dog than those who are too sick or too weak to have a pet [1].

Pet ownership appears to have a positive effect on the CV system. The discrepancies and inconclusive results of some available studies may be caused by confounding factors and differences in research methodology. Furthermore, some studies were observational and others interventional, limiting the ability to compare their results and draw definitive conclusions. In their clinical recommendations, the American Heart Association (AHA) points to pet ownership as a way to mitigate CVD risk. They conclude that pet ownership, especially ownership of a dog, may be associated with decreased CVD risk (Table ​(Table4).4). However, they caution that CVD risk reduction should not be the primary motivation behind pet adoption, rescue, or purchase [33]. Owning a pet should be based on sympathy and responsibility (caring for and treating the animal well) to the pet, while possible health benefits for the owner are only an added value and not an end in itself.

Clinical recommendations of the American Heart Association for having pets as a method of cardiovascular prevention. Based on [33]

Legend: Class IIb. may/might be reasonable; III, should not be performed/administered/other

Level B, recommendations are based on limited or inconsistent scientific evidence; C, recommendations are based primarily on consensus and expert opinion

Owning pets is important on a global scale. Many new studies have been published since the AHA position paper on the CV effects of pet ownership in 2013, but the relationship is still not fully understood. Generally, having pets appears to have a positive effect on the CV system, but a number of inconsistencies and contradictory results are caused by confounding factors, differences in research methodology, and the fact that some studies were observational and some interventional, which makes it difficult to compare results and draw conclusions. Probably, people who like pets get more health benefits from having pets. Prospective and interventional studies should be carried out to improve knowledge of the effects of pet ownership on the CV system and CVD risk. Existing evidence of the CVD benefits of pet ownership is sufficiently weak that the sole purpose of having pets should not be to prevent CVD.

The authors declare no conficts of interest relevant to this manuscript.

This article does not contain any studies with human or animal subjects performed by any of the authors.

This article is part of Topical Collection on Prevention of Hypertension: Public Health Challenges

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