This literature review provides the conceptual ground to the study of effects of animal-assisted therapy on end-of-life patients. It develops the current topic through a thorough critical review of pertinent and recent published literature that comes from a range of sources, predominantly journal articles. The review aims at revealing what has been said about the topic by the scholars in the field and determining the relevance of the current research. It also assists in refining the research question and identifying the overall purpose of the research.
The literature review has been logically structured to cover a variety of aspects in the current academic research into the healing power of animals and animal-assisted therapy. Firstly, it focuses on the historical aspect of the problem and the state of recent research into the history of animal-assisted therapy. Secondly, it provides an overview of the theoretical approaches to explanation of animal-assisted therapy mechanisms. Thirdly, it provides an overview of animal-assisted therapy outcomes in patients of various ages and in various settings. Specifically, it focuses on the recent findings in treatment of cancer, mental disorders, and emotional disorders, etc. Next, it briefly outlines concerns related to animal use in interventions and to patients’ perception of the therapy. Finally, the review concludes with a summary of the foregoing issues, which identifies a gap in the existing research.
Historical Perspective on Animals in Therapy
While the healing power of animals has been recognized by conventional medicine only recently, its historical aspects have been a subject of extensive research. Fine & Beck (2010) have explored the animal-human bond in the context of the historical kinship between people and animals. They point out that the bond between people and animals has been around since the time people started to domesticate animals. The link between a human and an animal was so strong that it grew into the animal’s position as a family member. Fine & Beck emphasize the mutual benefit of the people-animal bond and compare it to bonding between children and their parents, spouses, or between two friends.
The benefit of human-animal bonding for people’s emotional wellbeing was recognized back in the 17th century, when the first documented use of animals for therapeutic purposes was recorded. Serpell (cited in Morgan, 2008, p. 9) observes that back in 1969 John Locke recommended to encourage children to take care of animals as a way to develop their sense of responsibility and tenderness. Serpell further explains that the foregoing trend has remained popular throughout the subsequent centuries as a part of self-improvement philosophy (Serpell, 2000 cited in Morgan, 2008, p.9).
In his research into history of animal-assisted interventions, Serpell (2006) notes that the concept of the healing properties of animals was developed from an original belief in animals’ supernatural power found in hunter-gatherers tribes. It has evolved into modern understanding of animals as “agents of socialization” and sources of “relaxation and social support” (Serpell, 2006). In their historic overview of animal assistance in therapy, Palley, O’Rurke, and Nieme observe that the earliest therapeutic programs that engaged animals date back to the 1790s. At that time, mentally ill patients of the York Retreat, created in York, England, in 1796, were recommended to stroll in the gardens and interact with various domestic animals, for example rabbits or birds. They were also encouraged to take care of animals and do some gardening (Palley et al, 2010). Serpell (2006) further observes that animals had become common in the institutions for mentally ill people by the 19th century (p.3). Similarly, animals were used as part of therapeutic regimen at a center for people with epilepsy back in 1863, in Germany (McCulloh 1983 cited in Palley et al, 2010, p. 199).
Just as scientific medicine was rapidly developing at the end of the 19th century, the attention to animals as companions in therapeutic programs diminished (Kruger, Trachtenberg, & Serpell, 2004). A moderate resurgence in animals’ involvement in therapy took place in 1919 with the introduction of dogs for therapeutic use in St. Elizabeth’s Hospital for mentally ill people located in Washington, D.C. In the 1940s, healthcare professionals engaged animals to provide a diversion for veterans and help them improve their mood while in Pawling Army Air Force Convalescent Hospital located in Pawling, New York (Hooker, Freeman, and Stewart, 2002).
From available academic literature, it appears that throughout the first half of the 20th century therapeutic programs involving animals were discrete and sporadic. Similarly, Morgan in her “Examination of the Anxiolytic Effects of Interaction with a Therapy Dog” research on the basis of Johnson (1997) concludes that use of animals in a setting of healthcare was not widespread in the mid-20th century (Morgan, 2008).
The turning point in reinvigorating the healing value of animals was Levinson’s book “Pet-Oriented Child Psychotherapy” published at the beginning of the 1960s. Levinson’s groundbreaking book and his paper “The Dog as Co-therapist” were the first to consider the psychotherapeutic effects of children’s contacts with dogs, especially disturbed kids’ contacts. A subsequent pet therapy program for mentally ill patients was developed by Samuel and Elizabeth Corson back in the 1970s. It proved successful and led to “a widening circle of warmth and approval as a result of positive reactions of patients to pets, which included improved relationships with therapists, other staff on the ward, and patients” (quoted in Smith, 2009, p.21).
Next, the activity of the Delta Society, “a human services organization dedicated to improving people’s health and well-being through positive interactions with animals”, which was founded by Bustad and McCulloch. It laid foundations of currently widespread animal-assisted therapy, explaining that AAT is “a goal directed intervention in which an animal that meets specific criteria is an integral part of the treatment process.AAT is directed or delivered by a health/human service professional with specialized expertise, and within the scope of practice of his/her profession.” Delta Society focuses on achieving AAT purpose – to facilitate improvement in functioning of a human in a variety of spheres: physical, emotional, cognitive, and social. It is also pointed out that AAT can be either individual or group, and involves documentation and evaluation (Delta Society, 2012).
As Palley et al (2009) observe, the practice of Animal Assisted Therapy is quite common in American healthcare facilities today. They provide an overview of the facilities that use AAT and explain that these days the process of AAT mainstreaming is taking place, which requires further research in specifics of AAT. Morgan in her overview of AAT applications concludes that practitioners from various fields use AAT, especially psychotherapists.
Similarly, the works of Chandler (2005) and Nimer & Lundahl (2007) reveal that animals have been used in psychotherapy in a range of ways and populations. Specifically, Kruger et al (2004) list some diagnoses and health problems that are solved with help of AAT in psychotherapy today: anxiety, suicidality, post-traumatic stress disorder, conduct disorder, recovery from a variety of abuses (emotional, physical, or sexual), eating disorders, obsessive-compulsive disorder, mood disorder, and attention deficit hyperactivity disorder.
According to the findings by Nimer & Lundahl (2007), dogs are the most widely used animals in AAT. This is explained by a number of reasons, such as dog’s better availability than some other species of animals, better trainability, smaller risk of getting zoonotic infections, etc. As to the species that take the second position in being used in modern AAT practices, these are horses (Frederickson & Howie, 2000). Morgan also lists the following types of animals that are effectively used in AAT: birds, cats, rabbits, hamsters, guinea pigs, and other small animals, farm animals including cows, pigs, goats, lamas, and aquarium fish, etc (Morgan, 2008).
An in-depth and thorough overview of the current state of human-animal studies has been done by Shapiro & DeMello (2010). In their research article “The State of Human-Animal Studies”, scholars highlight the progress of human-animal studies across the globe. Based on recent data Shapiro & DeMello conclude that human-animals studies have faced unprecedented success and evoked great interest in scholars and laymen alike in over 300 countries. The field of human-animals studies has witnessed an explosive growth, with dozens of books being published annually to highlight academic research on human-animal bonding and its outcomes, as the authors observe (Shapiro & DeMello, 2010). AAT has seen a dramatic increase in its popularity, which made many colleges (first of all, veterinary ones) and higher institutions run programs on bonding between people and animals (Shapiro & DeMello, 2010)
Theoretical Foundations of Animal-Assisted Therapy
Just as AAT is winning recognition with the scholars, physicians, and general public alike, its theoretical foundations need further elaboration. From pertinent sources, it appears that there is no unified theoretical framework concerning AAT. Different researchers have made attempts to create a unified framework that would explain how and why interventions that engage animals have therapeutic potential.
A number of studies have offered a range of possible mechanisms of action, yet they mostly focus on peculiar intrinsic attributes of those animals that make contribution to therapy. Others, on the other hand, stress the importance of animals as certain living instruments that may be used for the purpose of effecting positive results in patients’ behavior as well as self-concept. The latter can be achieved in the process of acquiring various skills, when individuals learn to accept their responsibility as well as personal agency.
If to summarize the set of mechanisms which is thought to underpin AAT, one will have the following list of concepts and ideas: social support theory, attachment theory, learning theory, cognitive theory, social facilitation theory, and biophilia hypothesis (Kruger et al, 2004; Wesley, 2006; O’Haire, 2009; Fine & Beck, 2010; Kruger & Serpell, 2006).
According to Fine & Beck two most often cited theories in human-animal research are theories of social support and attachment (Fine & Beck, 2010). Both theories explain people’s engagement for animal care by the mechanism of the need for social support and the need for attachment. Developed by Bowlby back in 1969, attachment theory generally focuses on human need to be protected as well as to protect. Thus, attachment refers to any kind of behavior whose outcome is maintaining proximity to some other person that is thought to be able to cope with the world in a more effective manner (Fine & Beck, 2010). Flores (2004) explains that the attachment theory views addiction as an attachment disorder. The theory assumes that people are looking instinctively from their birth for close contacts with people and animals. When they do not reach the desired level of interaction and cooperation, they are “emotionally deficient and vulnerable to addition.” (Wesley, 2006, p. 64).
Social support theory is based on understanding of social support as support that is accessible to an individual through ties with other individuals or with animals. Animals are believed to be the source of social support within this theory, bringing psychological and physiological benefits to humans. For example, animals perform the role of social confidants when people feel alienated or fear contacting other people (Beck & Katcher, 1996 cited in Wesley, 2006, p. 58).
Bryant (2008) asserts that the majority of humans look for social support to assist them in adapting to some difficult situations. According to Bryant, social support is a foundation for a person’s mental health and normal functioning. Pets, Bryant believes, are an excellent resource for those who wish to secure social support and maintain their mental and physical well-being.
Biophilia hypothesis, which was introduced by Wilson back in 1984, refers to a proposal that humans possess an innate or genetic propensity to be attracted to animals and other living creatures (O’Haire, 2009, p.2). Within this hypothesis, it is believed that living things have a calming and relaxing effect on people who spend time with them/view them. Thus, it is believed that they may reduce levels of anxiety during stressful events. Reduction of negative health outcomes in patients who have spent some time in presence of animals has been evidenced by numerous empirical studies (for example, people who have spent some time watching aquarium fish tend to get calmer and their levels of anxiety are reduced) (O’Haire, 2009).
Learning theory, as interpreted by Kruger & Serpell (2006), states that an activity that is found pleasurable is likely to self-reinforce and thus it will most probably be reinforcing in the future (Kruger & Serpell, 2006). Brickel (1982), who offered this theory, emphasizes that animals may serve to divert patients from some stimulus they face, which generates their anxiety. Moreover, interaction with animals will prevent patients from avoidance and withdrawal (cited in Kruger & Serpell, 2006, p. 27).
Most often learning theory is associated with viewing animals as instruments of learning, when animals serve as certain instructional tools for positive changes, promotion in cognitive as well as behavioral aspects in people. Kruger et al (2004, p.10) explain that “such changes include the acquisition of nurturing and social skills, a sense of personal agency and responsibility, the ability to regulate impulsive and/or disruptive behavior, and the development of improved feelings of self-esteem and self-efficacy through performance accomplishment and positive role play.”
Social facilitation theory explains AAT in terms of understanding that presence of others has an arousing effect because of possible evaluation, apprehension or even a competition. Wesley (2006) cites one study in which cockroaches performed better while running towards the light when watched by some other cockroaches.
Cognitive theory, as interpreted by Geist (2011), is grounded on the idea that there is a continuous relationship between an individual’s environment, behavior, and cognition, which is necessarily reciprocal (Geist, 2011). If a person has an insecure attachment style, he or she may perceive the world through rejection or shame. Such people are likely to develop into unlovable individuals whose perception of others renders them unavailable. In order to restore a healthy understanding and sense of themselves, such people need to refer to self-knowing. Through interaction with animals people are likely to alter their view of themselves as bad or uncaring or unloving on the basis of their experience with a pet, which will improve their emotional condition (Geist, 2011).
While some research studies tend to use the attachment theory and others opt for the biophilia hypothesis or social support theory, most studies attempt to build conceptual frameworks, using a combination of a few theoretic approaches. For example, the study by Geist (2011) focuses on attachment and cognitive theories, whereas the study of O’Haire (2009) combines the social support theory with the biophilia hypothesis.
At the same time, the study conducted by Kruger et al (2004) employs a threefold approach focusing on the de-arousal properties of animals (rooted in biophilia hypothesis), their potential as instruments of learning, and their potential of social facilitation, social support, and attachment (Kruger et al, 2004). This may be explained by absence of a unified concept or model to explanation of the mechanisms of how and why animals are effective agents of AAT.
Positive Effects of Animal-Assisted Therapy
The abundance of empirical studies on effects of animal-assisted therapy is combined with these studies` diversity and variations. Studies that focus on AAT vary by types of interventions, study settings, participants, as well as conclusions drawn from particular findings. They also differ by the kind of species used in them; the most commonly used animal is a dog (Palley et al, 2009). Other frequently engaged species include fish, birds, cats, and horses. Among the age groups that have been involved in the studies one will find pediatric, adolescent, as well as adult and geriatric.
Most often researched conditions among the patients in the published studies were psychiatric disorders (including dementia and schizophrenia), heart failure and cancer. Settings also varied. While some studies took place in long-term care facilities, others were conducted in psychiatric facilities, rehab units, or even in laboratory settings. The following section provides a brief overview of the most recent studies on positive effects of animal-assisted therapy on patients from various age groups and with various health conditions.
The 2006 study on effects of dog therapy on minds of children and adolescents that have undergone inpatient treatment in psychiatric facilities has revealed that dog-assisted treatment accounted for children’s state of mind improvement. The following areas have been mentioned in terms of their improvement: vitality, social extroversion, intra-emotional balance, and alertness. As a result of this study, Prothmann, Bienert, and Ettrich (2006) have come to the well-grounded conclusion that engaging a dog into AAT would serve as a catalyzer for psychotherapeutic work with children and adolescents (Prothmann, Bienert, and Ettrcih, 2006).
Similarly, the study conducted by Villalta-Gil and her colleagues (2009) exposed benefits of dog-assisted therapy of chronic schizophrenia inpatients. Specifically, the researchers have come to the conclusion that dogs can benefit the patients who live in long-term care facilities in the following way. Importantly, they are likely to help such people improve their functioning within a community and improve their communication with non-disabled people around (Villanta-Gil, 2009).
A recent study of the effects of pet therapy on old age people, who are mentally disabled, has produced important results. Morretti et al (2011) aimed at defining whether pet therapy was effective in improving symptoms of patients with dementia, psychosis, and depression. Professionally trained dogs were involved in the study of a sample of people whose average age was 84.7 and who were mostly women. The patients reported high rates of satisfaction and enjoyment brought by the experience with pets, and said interaction with dogs helped them to calm down or focus on some memories from the past. More than 80 per cent said they would like to continue interaction with animals. The study has concluded that using dogs to treat mentally ill people in a non-pharmaceutical way is beneficial for people with depression (improvement among 50 per cent of the participants), dementia (10 elderly patients have reported improvement of their cognitive function), and psychosis (many said dogs helped them calm down) (Morretti et al, 2011).
Macauley (2006) found that dog therapy is useful in treating patients with aphasia. While the therapy seemed to produce no surprising results while estimating tests’ answers, the patients reported positive changes due to introduction of a dog to their sessions. The speech-language therapy was said to increase motivation, free the session atmosphere from burden of stress, and bring enjoyment to the patients.
Besides, Giaquinto & Valentini (2008) have fixed a range of benefits of dogs’ ownership for people’s psychological and physical conditions. In their research, they argue that trained dogs are helpful in preventing stress as well as hypertension; they help enhance people’s self-esteem and improve their interpersonal contacts, especially for blind owners (Giaquinto & Valentini, 2008)
Apart from dogs, horses have been successfully used to treat various groups of people. Klontz et al (2007) focused on equine-assisted therapy as an experimental project. The therapy program that was equine-assisted led to decrease in levels of psychological distress and made stronger patients’ psychological well-being (Klontz et al, 2007). The researchers reported that changes that were proved to be stable for the period of 6 months. This has been important for the development of modern psychotherapy.
AAT interventions have been helpful in treatment of patients with cancer. Johnson et al in their 2008 research “Animal-Assisted Activity among Patients with Cancer: Effects on Mood, Fatigue, Self-Perceived Health, and Sense of Coherence” discuss the peculiarities of animal therapy in cancer treatment. While no statistically significant differences were fixed between visits of trained dogs and inpatients’ mood, self-perceived health, or their sense of coherence, the participants of the study (30 adults that underwent nonpalliative radiation therapy) reported that the activities were beneficial for them. They recommended such visits to other patients in the early stages of the radiation therapy process (Johnson et al, 2008).
Other findings on animal-assisted therapy relate to the study of Cole et al (2007). In that study, hospitalized patients who suffered from congestive heart failure experienced reduced rates of pulmonary capillary wedge pressure, anxiety, systolic pulmonary artery pressure, and catecholamine levels after they had been visited by a volunteer with a dog. At the same time, no significant effect on patients’ heart rate was fixed.
In the study by Lust et al (2007), AAT led to decreased doses of analgesics and reduced pulse rate in patients of a rehabilitation facility. In addition, studies that focused on children in hospitals showed improved moods and improved heart rates, as well as decrease in pain (Kaminski, 2002; Braun et al, 2009). Also, within the setting of the nursing home reduced symptoms of depression were fixed in psychiatric patients (Souter & Miller, 2007). Back in 2006, the study by Sobo, Eng, & Kassity-Krich reported that a one-time visit of a volunteer with a trained dog led to decreased pain feeling among 25 children aged 5-18. All of them were from 1 to 3 days after surgery (Sobo et al, 2006).
While the majority of studies have been conducted in the settings of rehabilitation or long-term care facilities, or sometimes in a laboratory setting, the 2010 study by Horowitz has proved effectiveness and need of animal-assisted therapy integration into mainstream settings of health care facilities. In her research “Animal-Assisted Therapy for Inpatients”, Horovitz argues for introducing animal-assisted interventions in inpatient rehabilitation units, children’s hospitals and hospices, and critical care facilities on the basis of the empirically confirmed evidence of successful use of animals (namely, dogs) in these institutions (Horowitz, 2010).
Animal-Assisted Therapy Concerns
Animal-assisted therapy concerns are mostly related to the position and rights of animals that take part in interventions. For instance, Haubenhofer & Kirchengast (2007) report that animals, namely dogs, and their handlers have increased salivary cortisol levels when the therapy work is provided. At the same time, cortisol rates are lower in non-therapy control days. The length of a session also impacts the physical condition of an animal and its handler alike.
At the same time, it may happen that not every client will benefit from animal-assisted interventions. Therefore, visiting such difficult patients will mean acting unethical in terms of the animal use. Thus, patients should give their informed consent prior to sessions of AAT, while doctors need to work strategies on how to act in a variety of unpredictable situations (e.g. the dog dies) (Pearl, 2011).
Further, animals taking part in AAT should work based on a schedule. Unless the dog or some other animal is involved in a session, it should be provided with its own quiet place to wait for the next session. At the same time, as Wilkes points out, animals (dogs, in particular) should be inoculated, regularly examined and supervised by a qualified veterinarian (Wilkes, 2009).
Overall, the ethical considerations of involving animals in AAT should be based on understanding that animal health is of primary concern, so policies need to be established that would protect animals and define specifics of animals and animal handlers training (Palley et al, 2009).
The overview of the recent studies conveys the need for rigorous research in the field of animal-assisted therapy. While the historical aspect of health benefits of human-animal bonding has been studied thoroughly, more empirical research is needed to create a solid conceptual base for animal-assisted interventions. In particular, credibility of the existing theoretical approaches needs to be verified so that a unified approach to explaining mechanisms of animal-assisted therapy could be created. Importantly, it has been established that the healing power of animals is successfully used in conventional and unconventional medicine alike, leading to positive outcomes in patients with a variety of mental and emotional disorders, as well as other conditions. Besides, benefits of animal-assisted interventions for patients of all ages have been fixed. It has also been established that despite few existing concerns advancement of animal-assisted therapy is needed, especially in the field of the care for the elderly who are the most vulnerable group of inpatients. In particular, more research is needed in the field of animal-assisted therapy of end-of-life patients.