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OMAR Workshop September 10-11, 1987
This statement is more than five years old and is provided solely for historical purposes. Due to the cumulative nature of medical research, new knowledge has inevitably accumulated in this subject area in the time since the statement was initially prepared. Thus some of the material is likely to be out of date, and at worst simply wrong. For reliable, current information on this and other health topics, we recommend consulting the National Institutes of Health's MedlinePlus http://www.nlm.nih.gov/medlineplus/. This statement was originally published as: The health benefits of pets. Workshop summary; 1987 Sep 10-11. Bethesda (MD): National Institues of Health, Office of Medical Applications of Research; [1987]. For making bibliographic reference to the statement in the electronic form displayed here, it is recommended that the following format be used: The health benefits of pets. NIH Technology Assess Statement Online 1987 Sep 10-11 [cited year month day]; (3). OverviewMore than half of all U.S. households have a companion animal. Pets are more common in households with children, yet there are more pets than children in American households. There are more than 51 million dogs, 56 million cats, 45 million birds, 75 million small mammals and reptiles, and uncounted millions of aquarium fish. It is important at this time to assess whether these populations have any beneficial impact on physical, social, and psychological health. To this end, the National Institutes of Health convened a Technology Assessment Workshop on the Health Benefits of Pets on September 10-11, 1987. After a day-and-a-half of presentations by experts in relevant fields, a working group drafted the following report to provide the scientific community with a synthesis of the current knowledge and a framework for future research, and to provide the public with the information it needs to make informed decisions regarding the health benefits of pets. Throughout history animals have played a significant role in human customs, legends, and religions. Primitive people found that human- animal relationships were important to their very survival, and petkeeping was common in hunter-gatherer societies. In our own time, the great increase in pet ownership may reflect a largely urban population's often unsatisfied need for intimacy, nurturance, and contact with nature. However, it is impossible to determine when animals first were used specifically to promote physical and psychological health. The use of horseback riding for people with serious disabilities has been reported for centuries. In 1792, animals were incorporated into the treatment for mental patients at the York Retreat, England, as part of an enlightened approach attempting to reduce the use of harsh drugs and restraints. The first suggested use of animals in a therapeutic setting in the United States was in 1919 at St. Elizabeths Hospital in Washington, D. C., when Superintendent Dr. W.A. White received a letter from Secretary of the Interior F.K. Lane suggesting the use of dogs as companions for the psychiatric hospital's resident patients. Following this, the earliest extensive use of companion animals in the United States occurred from 1944 to 1945 at an Army Air Corps Convalescent Hospital at Pawling, New York. Patients recovering from war experiences were encouraged to work at the hospital's farm with hogs, cattle, horses, and poultry. After the war, modest efforts began in using animals in outpatient psychotherapy. During the 1970s, numerous case studies of animals facilitating therapy with children and senior citizens were reported. The Role of Pets in Cardiovascular HealthThe role of social support in cardiovascular health--a question not yet resolved despite considerable research--provides a rational framework for studying the possible benefits of pets beyond mere enjoyment and affection. Since psychological factors can elicit strong and immediate responses from the cardiovascular system, many studies are attempting to determine whether such influences ultimately affect the risk of developing cardiovascular diseases. The description of a "coronary-prone behavior pattern," or Type A behavior, and its link to the probability of developing overt disease provided hope that, with careful training, individuals could exercise additional control over somatic illness by altering their lifestyle. Relaxation, meditation, and stress management have become recognized therapies for attempting to reduce blood pressure before pharmacological methods are prescribed. It therefore seems reasonable that pets, who provide faithful companionship to many people, also might promote greater psychosocial stability for their owners, and thus a measure of protection from heart disease. Systematic research addressing this issue is scarce, and it has been difficult to draw definitive conclusions from the few studies with small sample sizes that have been completed. A selection of these, providing direct as well as indirect evidence relevant to this hypothesis, was reported at this conference. A plausible physiological basis for a beneficial influence of pets is provided by studies of heart rate in Old World monkeys and research of blood pressure in college students. There is now objective evidence, based on direct examination of coronary arteries, that monkeys housed in benign social environments and more frequently engaged in affiliative behaviors develop less severe coronary disease than monkeys repeatedly exposed to dominance-competitive interactions. It is possible that this decrease in atherosclerosis is directly related to the much lower heart rates that have been observed in these animals by means of telemetry, especially at times when they are engaged in social interactions with each other. Decreased coronary disease in animals with genetically lower heart rates also has been reported by others. Since elevated blood pressure also is associated with higher risk of developing significant coronary heart disease, demonstration that the presence of an unfamiliar dog lowers systolic blood pressure (but not diastolic blood pressure or heart rate) in college students is only a partially encouraging finding for proponents of a link between health and pet ownership. The experiment should be repeated, using the subjects' own pets rather than an unfamiliar animal, which may evoke a degree of anxiety in some people. A number of studies have reported that domesticated animals can influence physiological measures such as heart rate and blood pressure acutely, but conclusive data are needed to demonstrate that the magnitude of these effects is sufficient to be clinically significant and endure over a sufficiently long period of time to be beneficial. One approach would be a cross-sectional study showing lower heart rates or blood pressures in pet owners than in nonowners, although the problem of self-selection still remains. Experimental designs that randomly assign pets to some individuals andnot to others for a period of time would be ideal, although more difficult and costly. However suggestive the findings from studies of human physiology may be, the final link will have to come from clinical studies that demonstrate a direct relationship between pet ownership and either the incidence of, recurrence of, or mortality from heart disease in people. Results from one such study, presented at this conference, found that postmyocardial infarction survival rates were much higher among pet owners than among nonowners. However, as in the case of other social variables, only a small proportion (3.5 percent) of the difference in mortality was attributable to pet ownership itself. Because determining severity of disease is not yet an exact science, it is conceivable that all myocardial infarction (MI) patients who owned a pet were in relatively better health, as reflected by their ability to care for a household pet. It is therefore important to conduct rigorous prospective studies in which the effects of placing a pet with a randomly chosen sample of post-MI patients would be examined. In spite of the current insufficiency of data conclusively linking pet ownership to cardiovascular health, the evidence provided at this conference is sufficiently encouraging and intriguing to be worthy of serious followup. Those who own pets would surely be delighted to learn that they reap unexpected health and financial benefits (from lower health care costs) in addition to enjoying the companionship of the family cat or dog. Conference participants agreed that definitive conclusions on possible benefits of companion animals would require much larger sample sizes and more rigorous experimental designs than studies conducted thus far. Reexamination of data from one or more of the existing large epidemiological studies or collection of relevant followup data seeking to link incidence of disease with presence or absence of household pets could be a useful forerunner to costly de novo population studies. Alternatively, future national health surveys might include questions related to pet ownership among the demographic data collected so that the relationship of household pets to a variety of illnesses and conditions also could be determined. Pet ownership is a very personal decision reflecting an individual preference; this can bias the outcome of nonrandomized studies. Not only does ability to care for a pet imply better health, it also may reflect availability of more discretionary income, which may result in more investment in health care. A companion animal may not necessarily be appropriate for everyone; however, withholding a pet from someone who wants one could be as much a source of distress as forcing one upon someone who does not. Conference participants accepted that many questions would have to be examined when attempting to resolve these issues. Given the present state of knowledge, the best judge of the risks or benefits of pet ownership for optimal cardiovascular health is the individual. Hopefully, research developments will provide better guidance in the future. The Role of Pets in Child DevelopmentA number of empirical studies have investigated how children interact with pets and how they view their relationships with animals, including pets. These studies have taken two basic forms: (l) observational studies of actual interactions between child and pet and (2) interviews with children in which their attitudes and beliefs regarding animals in general, and their own pet in particular, were examined. These studies have demonstrated major developmental changes in how children interact with pets. For example, toddlers (2 to 3 years old) are more likely to hit, poke, or grab their pets (behaviors that might be considered aggressive) than are older children. Three- to 4-year-old children tend to pet their animals more than engage in other behaviors, while 5- and 6-year-olds generally hug, stroke, and massage their pets, suggesting both more sophisticated and "gentle" physical contact patterns and more empathetic social relationships. These age-based changes in patterns of behavioral interactions with pets are generally parallel to the developmental changes in interaction patterns that children have with familiar humans, including parents, siblings, and peers. Examination of children's attitudes toward pets reveals that many of them ascribe a rich range of social attributes to these animals. Some of these attributes--especially love and affection, companionship, intimacy, and nurturance--also are used in the children's description of their relationships with other specific people, but other attributes-- for example, ownership and entertainment--are uniquely ascribed to pets. Consider the attributes of companionship and love and affection. Most children rate their own pets very high on both characteristics while they rate neighborhood animals high on companionship but not on love and affection. (By way of comparison, siblings tend to be rated high on companionship but not on love and affection, while the reverse is the case for ratings of grandparents.) Taken as a whole, these results suggest that children's relationships with familiar animals, especially pets, are unique and different from their relationships with others in their social world. The relationship with pets typically is complementary to these other relationships rather than a substitute for any one type of human relationship. Of course, children differ in their attitudes and relationships toward pets, and some of these differences can be related to factors such as family size, presence or absence of younger siblings, and family income (most of the studies to date have been limited to samples of children from stable, suburban middle-class families, and generalization to other groups of children may not be valid). The long-term consequences for children of establishing such relationships with pets and other animals have not been studied to date in any detail, although a number of studies of children in diverse family circumstances suggest that, at least for some, the presence of a pet is greatly beneficial. On the one hand, it has been suggested that exposure to pets should facilitate the establishment and maintenance of relationships with peers, especially in grade and high school. On the other hand, there has been some concern that children who establish too intense a relationship with a pet may suffer in the development of sophisticated and meaningful relationships with other people. More research is needed to determine what such long-term consequences might be and to identify any conditions, situations, or characteristics of particular children whose specific relationships with their pets put them at risk for developing problems in subsequent social, emotional, and cognitive development. Prospective longitudinal studies in home or neighborhood settings would be very useful in this regard. Health Correlates of Pets in Older PersonsIn addition to examination of the effects of the human-companion animal bond among children and special populations of chronically ill or disabled adults, there has been widespread consideration of the benefits of companion animals for older persons. Interdisciplinary researchers in veterinary medicine, public health, and the behavioral sciences have begun to explore the health correlates of the human-animal bond and to examine the benefits of a wide range of pet-facilitated therapies on the health and functioning of the elderly. The assumption of a salutary effect of pet ownership on the health of older persons is based on a growing body of literature suggesting the importance of social ties and relationships for persons experiencing life changes affecting health or social situations. Two types of research predominate in this area. A few large-scale epidemiological studies are examining the association of pet ownership and attachment with the health and well-being of older persons living independently in the community. However, most researchers are involved in applied intervention studies examining the effect of pet-facilitated therapy or animal visitation programs on older persons in long-term care settings. Data from a national probability sample of 1,232 older persons living in the community reveal a lack of influence of pet variables on health outcomes in the general population of older persons: (1) no direct association was found between pet variables (pet ownership and attachment) and reported illness status or levels of depression and (2) no support was found for the hypothesized protective buffering role of pet ownership/attachment, and (3) there was stability in basic conclusions across subgroup analyses based on sex, age, and pet characteristics. However, a benefit of pet ownership and attachment in combatting depression, but not general illness status, was found among older persons in situations of personal stress who were without adequate human social support (e.g., bereaved persons without a close source of human support). Significant health benefits of human-animal interactions in the general population of older persons may be limited to persons in special "at-risk" circumstances. There is also new research examining the relationship between pet ownership, psychosocial variables, and health care utilization. These data collectively suggest that pet ownership may reduce the demand for care for medically nonserious problems. Studies of health benefits of pet programs for nursing home and health center residents often are flawed methodologically or reported incompletely. Yet the cumulative weight of these studies strongly suggests that psychosocial benefits can be gained from animal visitation programs for at least some older persons in such settings. For example, the presence of animals in institutional settings is associated with the tendency of older persons to smile and talk more, reach out toward people and objects, exhibit more alertness and attention, and experience more symptoms of well-being and less depression. Pet programs have proven superior in producing psychosocial benefits in comparison to some other alternative therapies (e.g., arts and crafts programs, friendly visitor programs, and conventional psychotherapy). The effect of exposure to pets on measures of physical and cognitive functioning is less clear. It is difficult to isolate intervention effects in the face of multiple symptoms and changing physiological conditions found in the severely impaired older population. Further, benefits for cognitively impaired persons may not carry over to times when animals are not present. The benefit of animal visitation and live-in programs should be addressed in relationship to other factors that influence long-term care services for older persons. Future research is needed to test explanatory models for understanding the health benefits of human/animal interactions in older persons. Two strategies for theory development were identified in this conference: (l) the generation of hypotheses from observations about the nature and consequences of the human-animal bond, and (2) the borrowing of theories and methodology from related scientific studies (e.g., the study of health and human social supports). Future studies need to recognize the heterogeneity of the older population and the complexity of the human-animal bond. Large-scale epidemiological studies of associations between people and pets often fail to reveal the expected relationships. We need to have realistic expectations of the benefits of pets given the number of other interacting social and behavioral risk factors that impinge on the health and functioning of older persons--whether in community or institutional settings. There is a need to specify the meaning of pets in everyday life and to explore the ways in which the presence of companion animals can affect the health and well-being of different segments of the older population. The examination of associated health benefits of companion animals for the elderly requires the researcher to go beyond a simplistic description of the presence or absence of a companion animal to consider the quality of that pet interaction. The relationship between the desire for and the reality of pet interaction should be examined further. The congruency between desire and reality may be a key factor in observed health impacts. The Role of Pets in Social and Therapeutic EffectsThe use of selected animals as agents in a wide variety of therapeutic approaches has become increasingly widespread in recent years. Two examples were highlighted in this section of the workshop: companion dogs for handicapped people confined to wheelchairs and "hippotherapy," horseback riding as part of a therapeutic program. Companion dogs provide wheelchair patients with a source of social stimulation that is typically more constant and reliable than most human companions, including spouses, siblings, or therapists. In addition, a number of empirical studies have demonstrated that the presence of a companion dog serves to increase the quantity and quality of attention directed toward the handicapped persons by both familiar individuals and strangers. This "magnet" effect of companion dogs can be of significant benefit to the handicapped individuals because research has clearly demonstrated that individuals with noticeable physical handicaps otherwise tend to be avoided or ignored by both familiar and unfamiliar individuals, relative to nonhandicapped people. At this point, study of long-term consequences of companion dog presence for this group of handicapped individuals has yet to be carried out. "Therapeutic riding" is an umbrella term to describe a variety of ways in which the horse may be used to influence the physical and psychological well-being of individuals. It incorporates riding skills and gymnastic exercises for emotional, cognitive, and sensorimotor benefits. For patients with movement disorders, specially trained physical and occupational therapists use therapeutic riding in which the horse influences the patient rather than the patient controlling the horse. The goal is to improve the patient's posture, balance, mobility, and function. At this time, solid data on the success of therapeutic riding is limited. The European literature on the topic is increasing. Future research is indicated to compare the efficacy of therapeutic riding with other clinical treatment procedures that do not involve the horse and to validate dramatic clinical observations. Safety and Risks in People-pet RelationshipsIn evaluating the health benefits of pet-people relationships, one also must consider the safety of this intervention for both people and pets -- for example, dangers to pets associated with chemicals such as insecticides and pesticides and people's risks of infections, allergies, and injuries associated with lack of veterinary medical advice. Although the risks associated with interaction are real for both people and pets, we need additional research to better define those situations, hazards, and populations with high risk as well as those situations and populations with very low risk. For example, reports from agencies in 50 states and studies of 284 nursing homes in Minnesota have shown that visiting and live-in pets can be relatively safe for residents in the supervised conditions of nursing homes. In the Minnesota study, no infections or allergic reactions and only two significant injuries were associated with pets during 12 months of research. Other studies emphasize that knowledge and motivation for people and appropriate selection and behavioral training of pets are essential to increase the safety of people-pet interactions. More research is needed to better define high- and low-risk conditions in defined populations and situations to develop more specific knowledge for promotion of safety and appropriate interactions between people and pets. Future Research DirectionsStudies on human-animal relationships originated with a focus on the beneficial aspects of pets. In time, four general research areas developed, including:
Methodologies for future research can begin without explicit hypotheses and proceed from descriptive studies of representative and, hopefully, random samples. There is nothing intrinsically wrong with extrapolating from attitudinal information as long as the sample is representative of the target population. It should be remembered that samples of convenience are prone to bias, and interpretation must be limited and made with great care. If the hypothesis is supported, research could proceed to cross-sectional and retrospective studies and then to long- range prospective investigations. A causal association between animal contact and human health can be demonstrated only by prospective studies. There are many promising areas of research related to potential health benefits of companion animals that would not only advance our comprehension of how to best utilize animals therapeutically but also would provide insight into the very nature of the link between people and animals in the general population. The major research questions include:
Future knowledge and research efforts should be directed toward specific health benefits of pets in the following areas:
The Working Group believes it is important to generate an increased awareness of the potential importance of human-animal interaction and involve scientists from a wide variety of fields for interdisciplinary collaborative research. Future studies of human health should consider the presence or absence of a pet in the home and the nature of this relationship with the pet as a significant variable. This workshop examined many of the relationships between companion animals, people, and health, and concentrated on the status of the scientific descriptions of these relationships. The Working Group, which drafted this report, believes that persuasive evidence was presented to conclude that pets are likely to be medically beneficial to some people's health. However, much is to be learned about many of these relationships before broad generalizations of medical benefit can be made. The committee hopes that investigators will heed the recommendations of this report in the design of future studies and that funding institutions will encourage their submission for peer review. Technology Assessment Panel
Professor and Director Emeritus Center to Study Human-Animal Relationships and Environments University of Minnesota Minneapolis, Minnesota
Director Center For The Interaction of Animals and Society University of Pennsylvania School of Veterinary Medicine Philadelphia, Pennsylvania
Behavioral Medicine Branch Division of Epidemiology and Clinical Applications National Heart, Lung, and Blood Institute National Institutes of Health Bethesda, Maryland
Chief Social Science Research on Aging Behavioral and Social Research Program National Institute on Aging National Institutes of Health Bethesda, Maryland
Director Tufts Center for Animals Boston, Massachusetts
Chief of the Laboratory of Comparative Ethology National Institute of Child Health and Human Development National Institutes of Health Bethesda, Maryland
Deputy Director Office of Animal Care and Use Division of Research Services National Institutes of Health Bethesda, Maryland Speakers
"Safety and Risk: The Experience in the Elderly" Professor and Director Emeritus Center to Study Human-Animal Relationships and Environments University of Minnesota Minneapolis, Minnesota
"Promising Research for the Future: Comprehension Before Intervention" Director Center For the Interaction of Animals and Society University of Pennsylvania School of Veterinary Medicine Philadelphia, Pennsylvania
"The Role of Pets in Childhood: Coping and Socialization" Professor Human Development and Family Studies Unit University of California at Davis Davis, California
"Protecting Pets From Hazards" Professor of Toxicology Director Illinois Animal Poison Information Center University of Illinois College of Veterinary Medicine Urbana, Illinois
"Historical Perspective" Professor and Dean Emeritus President of Delta Society Director People Pet Partnership Program Washington State University College of Veterinary Medicine Pullman, Washington
"Patterns and Trends of Pet Ownership in the United States" President American Veterinary Medical Association Whittier, California
"Companion Animals in Hypertension and Coronary Heart Disease" Associate Professor Department of Health and Nutrition Sciences Brooklyn College of the City University of New York Brooklyn, New York
"Contributions of Family Theories to Companion Animal Studies" Professor Center to Study Human-Animal Relationships and Environments University of Minnesota Minneapolis, Minnesota
"Pet Ownership as a Protective Factor Supporting the Health of the Elderly" Professor and Acting Chairman Department of Behavioral Science University of Kentucky College of Medicine Lexington, Kentucky
"Socializing Effects of Animals for People With Disabilities" Director Human-Animal Program University of California at Davis School of Veterinary Medicine Davis, California
"A Theoretical Perspective: The Health Significance of the Living Environment" Associate Professor of Psychiatry University of Pennsylvania Philadelphia, Pennsylvania
"Social and Therapeutic Effects of Therapeutic Riding/Hippotherapy" Referent Fur Internationale Kontakte Kuratorium Fur Therapeutisches Reiten Bergisch Gladbach-Refrath Germany
"Pet Selection in Therapeutic Programs" Director, Higher Education Programs Humane Society of the United States Washington, D.C.
"Politics of Pets" Staff Professional U.S. Senate Banking-Housing Committee Washington, D.C.
"Coronary Disease: Discovering the Behavioral Connection" Associate Professor of Psychology and Psychiatry University of Pittsburgh Pittsburgh, Pennsylvania
"Methodologies for the Future" Professor of Epidemiology Department of Family Practice University of Kentucky College of Medicine Lexington, Kentucky
"Attitudes and Ethical Structure With Regard to Child Development" Director Laboratory of Psychophysiology Professor Faculty of Sciences and Technics Besancon, France
"Nursing Home and Health Care Center Residents" Quality Assurance Coordinator Medical District 5 Veterans Administration Pittsburgh, Pennsylvania
"Potential Health Hazards Associated with Pet Animal Contact" Epidemiologist Parasitic Diseases Division Center of Infectious Diseases Centers for Disease Control Atlanta, Georgia
"Ethical Issues in Human and Animal Interactions" Clinical Assistant Professor Tufts University School of Veterinary Medicine Boston, Massachusetts
"Influence of Pets on Cardiovascular Response of Healthy Students" Associate Professor and Research Director Department of Family Medicine Uniformed Services University of the Health Sciences Bethesda, Maryland Planning Committee
Professor and Director Emeritus Center to Study Human-Animal Relationships and Environments University of Minnesota Minneapolis, Minnesota
Director Center For The Interaction of Animals and Society University of Pennsylvania School of Veterinary Medicine Philadelphia, Pennsylvania
Professor and Dean Emeritus President of Delta Society Director People Pet Partnership Program Washington State University College of Veterinary Medicine Pullman, Washington
Social Science Analyst Office of Medical Applications of Research National Institutes of Health Bethesda, Maryland
Director Office of Laboratory Animal Science National Cancer Institute National Institutes of Health Bethesda, Maryland
Director Animal Resources Program Division of Research Resources National Institutes of Health Bethesda, Maryland
Director Human-Animal Program University of California at Davis School of Veterinary Medicine Davis, California
Special Assistant to the Director National Center for Nursing Research National Institutes of Health Bethesda, Maryland
Executive Director Delta Society Renton, Washington
Behavioral Medicine Branch Division of Epidemiology and Clinical Applications National Heart, Lung, and Blood Institute National Institutes of Health Bethesda, Maryland
Chief Mental Disorders of the Aging Research Branch National Institute of Mental Health Rockville, Maryland
Chief Social Science Research on Aging Behavioral and Social Research Program National Institute on Aging National Institutes of Health Bethesda, Maryland
Veterinary Medical Officer Center for Veterinary Medicine Food and Drug Administration Rockville, Maryland
Director Tufts Center for Animals Boston, Massachusetts
Therapeutic Recreation Specialist Patient Activities Department Warren Grant Magnuson Clinical Center National Institutes of Health Bethesda, Maryland
American Veterinary Medical Association Human-Animal Bond Committee Delta Society--Board Member Veterinarian MacArthur Animal Hospital Washington, D.C.
Chief of the Laboratory of Comparative Ethology National Institute of Child Health and Human Development National Institutes of Health Bethesda, Maryland
Deputy Director Global Epidemiology Investigations Service Centers for Disease Control Atlanta, Georgia
Deputy Director Office of Animal Care and Use Division of Research Services National Institutes of Health Bethesda, Maryland Conference Sponsors
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