Man’s Best Friend

By Mike de Lota, M.D. – March 1, 2021

Animals have long been intertwined with human partners throughout history. Prehistoric cave paintings depict humans hunting side by side with canines; Egyptian hieroglyphs document that civilization’s domestication and worship of cats; and bird keeping was a popular European practice during the age of exploration well into the early 20th century. Throughout the vast sea of time and across numerous cultures, humans have turned to animal companionship for both survival and enjoyment. As Sylvia Plath once said, “How we need that security. How we need another soul to cling to, another body to keep us warm. To rest and trust; to give your soul in confidence.” Although referring to human relationships, her wisdom is applicable to the connections we share with our pets. Not only do pets satisfy our basic need for companionship, but recent studies have shown that pet ownership can have many physical and mental health benefits as well.

Cardiovascular Benefits

Pet ownership may have a positive impact on one’s cardiovascular health. While ongoing research studying the link between these two has yielded mixed findings, several studies have shown a positive correlation. Perhaps the most obvious correlation is that pet ownership (specifically dog ownership) was linked with increased activity levels. One study found that dog owners were more likely to walk either with or without their dogs versus dog non-owners. Once they were told about the health benefits of walking their dogs, dog owners tended to increase their step count during walks.

The American Heart Association also investigated this correlation and reported that, among people with cardiovascular disease, pet ownership may provide cardioprotective benefits. Two studies showed that after a heart attack, dog owners had a mortality rate roughly four times lower than dog non-owners. It was believed that dog ownership not only led to increased physical activity levels amongst dog walkers, but it also helped to improve depression after a heart attack. This helps increase compliance with medications, follow-ups, diet and exercise. More recent studies have lent support to this relationship and found that lack of pet ownership was a significant predictor of mortality.

Hormonal Effects

Another study compared the heart rate and blood pressure of pet owners and pet non-owners and found that pet owners had overall lower heart rates and blood pressure at rest, significantly smaller increases (reactivity) in these levels when stressed and were able to recover faster from stress. Among pet owners, the quickest recovery and lowest reactivity occurred when their pets were present, suggesting that pets had a direct calming effect on their owners. A 2011 study investigated the mechanisms behind this calming effect and found that positive associations with pets led to a reduction in stress hormones such as cortisol (a hormone linked to type 2 diabetes, blood vessel damage, weight gain and high cholesterol) and salivary alpha-amylase (a hormone elevated in response to physiological and psychological stress). 

Another hormone that could play a key role is oxytocin, which promotes emotional attachment, positive physical contact and social cognitive processes. It is released during childbirth, breastfeeding, orgasm and with physical touch. Higher levels of oxytocin were observed in people when petting animals, especially with dogs whom they have a bond with (ie “bonded”), and lead to lower heart rate, improvement of depression and anxiety and perception of pain. Another study found that after a stressful day at work, oxytocin levels were increased among women interacting with their dogs but not among men. 

Psychological Benefits

Pets have long been touted for their ability to provide their owners with emotional support. These effects have been underscored in specific populations including military veterans suffering from PTSD (post-traumatic stress disorder) and persons with HIV/AIDS suffering from depression. By providing companionship, dogs improved PTSD symptoms in military veterans by reducing feelings of loneliness, depression, worry and irritability. Among persons with AIDS, pet owners had fewer symptoms of depression than pet non-owners. It was thought that pets reduced feelings of isolation, provided companionship and provided a welcome distraction to symptoms of depression and anxiety. Some studies have gone as far as to say that pets intuitively try to alleviate their owners’ symptoms in times of crisis, suggesting that pets can “sense” when their owners are suffering.

Another way in which pets provide emotional support is through facilitating communication. Pets provide an outlet of communication for their owners that is very different from one that can be provided by one’s friends or family. Pets are great listeners and allow owners to confide in them in a way they are not able to confide in other people. Since they are perceived to be non-judgemental and provide love and affection unconditionally, this helps foster a level of trust and support that might not be attainable with others. Pets provide relationships free of conflict, preconditions and “drama.” They have also shown to increase one’s social interaction with friends and family as well as peripheral social interactions with others. One study found that pets helped promote interactions with others that would otherwise not be possible, such as when dog walkers meet and interact with each other. In these informal settings, conversation is typically casual and focused around a mutual interest which helps to facilitate a “built-in” connection. This is especially helpful in people vulnerable to isolation such as those suffering from mental illness, cognitive impairment, chronic medical conditions or the elderly. 

Finally, pets can positively impact mental health by promoting a sense of self-worth for their owners. In giving their owners responsibility, pets promote a feeling of duty and provide their owners a sense of control. This gives pet owners a reason to live. In anxious and depressed patients, self-empowerment, a sense of control, an obligation to duty and a sense of purpose are imperative in the road towards healing.

However, it’s not all roses and rainbows, as any pet owner will tell you. Pet ownership comes with its own unique challenges including monthly pet expenses, coordinating care, veterinary visits and the pain of losing your pet. For many, these costs pale in comparison to the physical, mental and emotional benefits that only animal companions can provide. Through their tangible and intangible contributions to our health and psyche, humans will continue to rely on pets “to rest and trust” and “to give [our souls] in confidence.”


Dr. de Lota is a family medicine physician working at Austin Regional Clinic. He enjoys treating people of all ages and has a passion for preventative care, evidence-based medicine and patient education.


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