Pet ownership has been recognized by the National Institutes of Health and others as having many benefits for the health and welfare of humans and animals. Under some circumstances this may include the prevention of, or improved recovery from, coronary diseases and disorders.
Heart disease is the number one killer in the United States according to the National Library of Medicine . While appearing in many forms, the most common form of heart disease is the narrowing and/or blockage of the coronary arteries . This can happen slowly and over time, a major reason for heart attacks. Coronary artery disease (CAD) can result in the weakening of the heart and lead to arrhythmias, irregular and weak heartbeats . Some risk factors for CAD and other heart diseases include high cholesterol, high blood pressure, sedentary life style, poor diet, and smoking .
State of Current Research
A landmark study by Freidman et al (1980) followed 92 people who had been treated for myocardial infarction or angina pectoris and discharged. Survival after one year was 94% (50/53) for pet owners and 72% (28/39) for those with no pets. Pet ownership correlated with survival and reduced severity of disease. They replicated this finding in a larger study of 424 myocardial infarction survivors.
A number of subsequent studies have produced mixed results. Qureshi et al (2009) found a beneficial effect only for past cat ownership, not present cat or dog owners. Parker et al (2010) found that pet owners were actually less likely to recover from acute coronary syndrome, especially cat owners.
When looking at longer term risk factors, Australian research found that pet owners had higher rates of risk factors such as elevated blood pressure, being overweight, and smoking—and were not healthier overall. A Finnish survey found pet owners were more likely to have high blood pressure or hypertension, and that pet owning had no correlation with rates of myocardial infarction or angina pectoris.
Some researchers consider that the role of confounding factors make it impossible to accurately assess the impact of companion animals on human health using observational studies or that when other lifestyle and demographic factors are taken into account, the role of pet ownership may be negligible (see also).
Allen et al (2001) found that those who acquired pets had a blunted blood pressure response to stress when compared to a match control group. And elderly volunteers provided with goldfish as pets demonstrated a decrease in blood pressure.
Visiting or Therapy Animals
Some of the advantages of animal contract may occur with just brief visits from friendly animals. However this finding varies considerably depending on a person’s attitudes to animals, and non-pet owners may find the presence of a pet more stressful than its absence.
Mechanisms of Effect
Exercise or Other Meaningful Activity
The benefits of dog ownership often include higher levels of physical activity  The acquisition of a dog has been shown to increase activity levels , which contribute to better physical quality of life.
Curiously, this higher rate of activity amongst dog owners is often not associated with lower body mass index or a longer lifespan . And some studies do not find that dog ownership is associated with higher activity levels at all.
Ownership of other pet species, such as cats, may be associated with particularly inactive lifestyles. However these pats may still be associated with health benefits from pet dogs as may dogs that are not regularly walked. These pets may add complexity, structure and interest to daily life that encourages a more positive mood and engagement with the wider community .
Social Support or Non-Stressful Focus
Animals such as dogs are perceived as non-judgmental and hence tend to be a calming and reassuring influence (Allen, 2003). Non-judgmental social support is known to act as a stress buffer, reducing the severity of physical and psychological damage caused by negative experiences.
Dogs also facilitate social interactions between their owner and other people and help engage owners positively with their neighborhood community . Animal may also provide neutral or positive focus and source of daily structure and so decrease anxiety.
Herrald et al (2002) found that pet owners were more compliant in completing cardiovascular rehabilitation programs after surgery to deal with cardiac insufficiencies. The authors suggested the cause of this result might be the extra social support provided by the pet, pets aiding in structuring daily activities, or even the patient’s desire to stay alive so that someone is available to care for the pet.
Reduced Blood Pressure, Stress Reactivity or Increased Heart Rate Variability
Some studies have found that people with pets have a lower resting blood pressure and it has been suggested but not yet confirmed that blood pressure may be lowered via the effect of the hormone oxytocin. However other studies have not replicated this finding or even found the opposite relation. Pets may make blood pressure less reactive when stressed. Thus, even when resting blood pressure is not effected pets may act as a buffer to sudden changes or peak blood pressure. This buffering effect may also occur in the presence of animals that are not owned pets. Conversely, people who prefer to avoid pets may experience no benefit, or even become stressed, in the presence of a pet. Heart rate variability (irregular inter-beat interval) is associated with a range of better heart health outcomes. Both walking with a dog and having a dog visit at home have been shown to improve this parameter in elderly individuals.
Pets should be considered adjunctive to other treatments as part as a overall treatment plan, not as direct substitutes for human companionship, therapy or medication. Consideration should be given to any manner in which the pet might be difficult to care for, represent a health risk (e.g. disease, allergy or injury, risk of bereavement, or become an obstacle to emergency or routine health care for the owner. Most importantly, the benefits of pet ownership depend upon forming a positive and mutually-beneficial bond between human and animal, and care must be taken to foster and support this outcome.
The benefit of pet ownership in all areas of health has received wide acclaim, but may have been over-stated in some cases as disproportionate attention is focused on positive findings. It should be appreciated that the correlation between pet ownership and cardiac health is complex and not currently well-understood. Observed correlations may reflect a complex combination of actual causes and incidental correlates of pet ownership that vary geographically, culturally and by pet type. Pet ownership should not be considered a panacea, but may be beneficial under specific circumstances where the attachment between human and animal is likely to form in a positive manner and so have a positive influence. This outcome should not be considered a foregone conclusion as introducing a pet to inappropriate household can increase stress and have a negative effect on health. Relevant health professions should be consulted in making pet ownership decisions that will affect people with serious health risks or conditions.
Pets can provide and enriching experiences and the currently ambiguous state of the literature should not represent an obstacle to pet ownership. People who already own pets should not be subject to the distress of being separated from that animal unless absolutely necessary for their well-being or that of the animal. And under the right circumstances companion animals may help some people avoid or recover from serious cardiovascular illness.
The strongest data relating to cardiac benefits of pet ownership currently relates to: the elderly, people with a high stress or isolated lifestyles, people with positive attitudes towards pets (c.f. ambivalence or anxiety; Zilcha-Mano et al, 2012) and people who have, or are actively interested in acquiring, a pet.
Friedmann, E., Katcher, A., Lynch, J., & Thomas, S. (1980). Animal companions and one-year survival of patients after discharge from a coronary care unit. Public Health Reports. 95(4). 307-312.
The authors conducted a study of social isolation and social support on the survival of patients from coronary care units (CCU). To the authors’ knowledge, this was the first study to include pet ownership as a criterion for consideration. The study found that only six percent of pet owners died a year after discharge from the CCUs, as opposed to over a quarter of the non-pet owners dying a year after discharge. To the authors’ minds, the study confirmed the importance of independent social factors and their role in health status and patient survival.
Friedmann, E. & Thomans, S. (1995). Pet social support, and one-year survival after acute myocardial infarction in cardiac arrhythmia suppression trial (CAST). Am J Cardiol. 76. 1213-1217.
A total of 424 subjects were recruited for the study of survivability and pet ownership one year after acute MI. One hundred twelve participants owned pets. There were enough subjects with dogs or cats to test each variable separately. Dog ownership was found to be an independent predictor of survival status, while cat ownership was dependent on social support. The authors also note that there was no evidence of differences of the physiological status of dog owners and non-owners, answering the claim that healthier people might own dogs in the first place.
Friedmann, E. & Son, H. (2009). The human-companion animal bond: How humans benefit. Vet Clin Small Anim. 293-326
Friedmann and Son’s article highlights studies and experiments that investigate the benefits of the human-animal bond on general health. The authors highlight areas where a person’s stress responses are lowered or reduced in the presence of dogs, cats, other animals, and even simulated animal presences, such as videos. The article reports that pet owners had reduced physiological cardiovascular risk factors, such as lower levels of serum triglyceride and blood pressure. Owners of dogs were more likely to be alive one year after being hospitalized for coronary heart disease. The authors also include short descriptions of studies in tables organized by experimental design, participants, outcomes, and results.
Friedmann, E., Thomas, S., Son, H. (2011). Pets, depression, and long term-survival in community living patients following myocardial infarction. Anthrozoos. 24(3). 273-285.
This study investigated whether pet ownership contributed long term to the survival of post myocardial infarction (heart attack) patients. Previous studies had demonstrated the correlation of pet ownership to lower mortality rates after a one-year period. The study found that pet ownership contributed to long-term survival after controlling for the effects of depression.
Mc Connell, A. R., Brown, C. M., Shoda, T. M., Stayton, L. E., Martin, C. E. (2011). Friends with benefits: On the positive consequences of pet ownership. Journal of Personality and Social Psychology. Advance online publication. doi: 10.1037/a0024506
The authors conduct three studies to investigate if the benefits of pet ownership reported for individuals in a clinical setting or with medical needs extent to healthy individuals as well, and if so, to what degree? The studies investigated the well being of participants, some of who owned pets. The authors found that pet owners reported higher well being, fewer stresses, and less depression and loneliness than non-pet owners. Also, being psychologically close to a pet did not seem to mean the pet owner distanced his or herself from human interaction.
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