Effects of Small Dogs on Vital Signs in Elderly Women: A Pilot Study, The

Cardiopulmonary Physical Therapy Journal, Mar 2004 by Luptak, Jane E, Nuzzo, Nancy A

ABSTRACT

Purpose: The emotional benefits of animals to humans are something that nearly every pet owner will attest to. But do the benefits extend beyond the emotional level to the extent that they affect physiological measures such as blood pressure or heart rate? The purpose of this study was to examine the effects of nonbonded (unknown to subject) dogs on vital signs [blood pressure (BP), heart rate (HR), and oxygen saturation (SpO^sub 2^)] in elderly women. This study was a pre-post test design. Methods: Fifteen females (83 ± 3.5 years) who reportedly enjoyed dogs volunteered to participate in the study. The women were randomly broken into 3 groups of 5. Each participant had a resting BP, HR, and SpO^sub 2^ recorded. Two dogs were then brought into the testing room where the subjects held and passed around the dogs. After 10 minutes, a second reading was taken. The dogs were then removed from the room and the subjects sat quietly for another 5 minutes. After this time, their BP, HR, and SpO^sub 2^ were taken for a final time. Results: The blood pressure of 1 3 out of 14 subjects decreased after interacting with the dogs (1 subject's blood pressure was not able to be recorded). A statistically significant decrease in systolic blood pressure was observed, while a trend toward significance was found for diastolic blood pressure. Heart rate also showed a trend toward significant decrease following the interaction. No significant change in oxygen saturation was noted. Conclusion: This study suggests that dogs may have a beneficial effect on the BP and HR in elderly women.

INTRODUCTION

Cardiovascular disease accounts for more than half of all mortality in industrialized countries.1 Controlling hypertension, a prevalent risk factor of cardiovascular disease, is of major concern2 and is frequently managed by various medications.3 Since daily medications can cause side effects, seeking alternate methods for lowering blood pressure warrants pursuit.2 Alternate activities such as relaxation exercises, yoga, and calming music are commonly suggested, and studies have shown that a low fat, low sodium diet in conjunction with a stress free environment have the best long-term results for maintaining lower blood pressure.2,4-6 However, as these types of lifestyles require discipline and effort, they are frequently underutilized.7

Controlling high blood pressure is important to prevent damage to the heart and circulatory system, as well as the kidneys, retina, brain, and other organs.3 In females approximately 80 years old the average resting blood pressure ranges between 140/90mmHg8 and 1 70/90mmHg,9,10 with an average resting heart rate of 70 to 78 bpm.8,9

Although limited, research has been done to examine the effects of animals on several variables in humans. Several of these studies have explored the psychological aspects of pet-human interaction.11,12,13 Giuliano et al14 described the benefits of the human-animal interaction to include: an increase in social interaction, psychosocial function, life satisfaction, and mental function, as well as improvement in depression, social competence, and psychological well-being. Similarly, Doyle and Kukowski12 reported that pet-facilitated therapy had general effects of 'eliciting speech from nonverbal individuals, creating emotional reactions from the withdrawn, uncommunicative patients, educing nurturing and affection from violent-prone individuals, and promoting more positive attitudes among people involved in caring for the terminally ill.'

Baun et al15 conducted a meta-analysis of available research related to the use of companion animals as an aid to human health. With stress, the sympathetic system is stimulated, causing increases in the pumping action of the heart and thus raising blood pressure. The results of this meta-analysis suggested that relaxation, being the opposite of stress, is a complex psycho-physiologic process characterized by activation of the parasympathetic nervous system. Therefore, if a companion animal can function to enhance the parasympathetic nervous system response, interacting with a companion animal may produce desirable effects of decreased heart rate and blood pressure. From this meta-analysis, Baun et al15 found that petting a dog may have relaxing effects, but more research is needed before any definitive conclusions can be made regarding the effectiveness that petting a dog has on blood pressure and peripheral skin temperature.

There is some evidence to suggest that owning a pet may improve mortality rates following hospitalization for coronary heart disease. Friedman et all16 found that pet owners who had been hospitalized with coronary heart disease had a 5.6% mortality rate in the first year following hospitalization, whereas their non-pet owning counterparts had a rate of 28.2%. This result lends further credence to the notion that pets may be an important adjunct to optimizing cardiovascular health in humans.

Therefore, the purpose of this study was to examine the effects of nonbonded dogs on the blood pressure, heart rate, and oxygen saturation in elderly women. Nonbonded dogs are those with which the subject has never had contact so that no prior bond exists. Nonbonded dogs were used for 2 reasons: (1) to simulate a typical animal-assisted therapy (AAT) session during which the animals are nonbonded, and (2) there is limited research currently available on the effects of nonbonded dogs on vital signs in the elderly. In addition, this was a preliminary study using volunteers from an assisted-living facility in which the residents were prohibited from having pets. The study was done solely on females as they were the only individuals who responded to the call for participants (see methods). The hypothesis of this study was that blood pressure and heart rate levels would decrease after interaction with the dogs and that the oxygen saturation levels would not be affected.