Humanity’s relationship with animals has evolved throughout history, with early Homo sapiens acting in the role of both predator and prey. In the 1700s, dogs were used merely for actions such as hunting, tracking, and other physical labor, and were not considered to be the loving pets of today’s culture. Since many at this time viewed dogs as workers rather than faithful companions, it was peculiar that King Frederick of Prussia used the term “man’s best friend” in 1796 to reference his own dog, an Italian greyhound. In 1821, the phrase made a reappearance, and its debut in the United States, when the New York Literary Journal published a poem composed by C. S. Winkle.1 The short piece reflects the modern view of the dog, when it states, “The faithful dog— why should I strive/To speak his merits, while they live/In every breast, and man’s best friend/Does often at his heels attend.”2 As the Industrial Revolution took hold in the 1800s, and urbanization in the United States expanded, the large, growing middle class started owning pets and bringing them into the home setting for uses other than labor.3 From then on, the dog has been known as man’s best friend, and the expression has become extremely commonplace.4
Today, we live in a culture enthralled by animals, where the average household contains 1.7 dogs,5 and Americans spend an average of $70 million each year on their pets.6 Since animals and pets are a consistent part of our culture, their use has come full circle, as they now function as both workers and companions. Creation of the first animal-assisted therapy programs occurred in the 1980s, and since then, the healthcare field has grown and developed to include more service and therapy animals.7 Recent research trends have shown that these trained animals help promote psychosocial well-being during stressful periods, such as stays in the hospital, and their presence has improved the healing process. Additionally, these therapy and emotional support animals play a large role in identifying subtle indications that a person requires assistance due to their particular condition, such as recognizing the onset of a seizure or hypoglycemia.8 Although there has been controversy surrounding the increased use of these animals, they do promote favorable results among all populations and all age groups, in the areas of mental health, behavioral health, and speech and language. Therefore, by including them as a part of a multidisciplinary team, there is a potential for improved patient outcomes and decreased healthcare costs, which in certain circumstances can further enhance the healthcare system in the United States.
Service animals, however, play a different role than that of therapy animals as utilized in the healthcare field. In order to understand how therapy and emotional support animals are impacting the modern world, it is first important to differentiate between service, therapy, and emotional support animals. Although they may all seem very similar in concept, the intended purpose, certifications, requirements, and training are distinct. Ally Fuhs, a dog trainer in Michigan, suggests that service dogs can be equated to medical equipment, since they are trained to perform tasks that would aid the person in living with their illness or disability.9 Fuhs also makes the distinction between these animals and therapy animals when she states that service animals are qualified to aid “one person with a disability,” while therapy animals “provide comfort and support for people in [a] wide variety of situations.”10 These therapy animals are most often seen in nursing homes and schools because their purpose is to be a companion to people who may need extra support.
Emotional support animals come into play as a third tier, below both service and therapy animals, since they do not have any formal training or task requirement assigned to them. What many fail to recognize is that therapy animals, while meant to provide comfort and support, have certain behavioral requirements that emotional support animals do not. The training these animals undergo is more extensive than the average obedience training that is often associated with owning a pet. In order for an animal to become certified as a therapy animal, they must first pass the American Kennel Club’s Canine Good Citizen Test. This evaluation measures how the animal reacts to strangers and how well they can walk on a leash, walk through a crowd, and follow simple commands.11 The animal is also assessed for responsiveness to medical equipment, loud stimuli, anger, intensity, and being restrained, as in a hug.12 After receiving this certification, the animal needs to be assessed for temperament and handling by a licensed organization.13 Emotional support animals do not have any of the same requirements, as they are considered pets. Due to this distinction, emotional support animals cannot be in public spaces where pets are not normally permitted. Not only can their lack of training be harmful to other humans, but there is also the risk that they will act out against other animals and threaten people with qualified service animals. Therefore, the only animals that are allowed to have unlimited public access are traditional service animals. Emotional support animals come into play as a third tier, below both service and therapy animals, since they do not have any formal training or task requirement assigned to them. What many fail to recognize is that therapy animals, while meant to provide comfort and support, have certain behavioral requirements that emotional support animals do not. The training these animals undergo is more extensive than the average obedience training that is often associated with owning a pet. In order for an animal to become certified as a therapy animal, they must first pass the American Kennel Club’s Canine Good Citizen Test. This evaluation measures how the animal reacts to strangers and how well they can walk on a leash, walk through a crowd, and follow simple commands. The animal is also assessed for responsiveness to medical equipment, loud stimuli, anger, intensity, and being restrained, as in a hug. After receiving this certification, the animal needs to be assessed for temperament and handling by a licensed organization.14
Due to the increase in emotional support animals, the United States Department of Transportation updated and amended the Air Carrier Access Act in 2021. The only service animals that are now allowed on aircrafts are dogs; any other emotional support or therapy pets, such as dogs, turtles, chicks, rabbits, birds, cats, potbellied pigs, fish, or horses are not permitted.15 However, since psychiatric service animals aim to aid those with psychiatric illnesses, they are in the same category as regular service animals and would not require any additional documentation.16 These animals are trained to accomplish tasks that are stressful for their owner, such as turning on the lights in a dark room to diminish the anxiety-inducing stimuli that accompany such events.17 Lastly, all service animals that are intending to board an aircraft are required to have a completed Department of Transportation Service Animal Air Transportation Form as well as a Service Animal Relief Attestation Form.18 Passengers can also be limited to two service animals, and the animals can be required to fit within the passenger’s foot space on the plane, just like any other personal carry-on item.19
These new, stricter requirements have caused many people to reassess whether their pet can and should be classified as a service animal. According to the Department of Transportation, a service animal is limited to any dog, “regardless of breed or type, that is individually trained to do work or perform tasks for the benefit of a qualified individual with a disability.”20 Disabilities that are qualified for a service animal include any “physical, sensory, psychiatric, intellectual, or other mental disability.”21 The Department of Transportation also requires service animals to follow specific behavioral guidelines. These include the expectation that the service dog will not “run around freely, bark or growl repeatedly, injure people or urinate or defecate outside of allowed areas,” while “remaining under the control of [its] handler.”22
All three of these categories of assistance animals have begun to have a greater presence in the healthcare field. Social workers, child life specialists, psychologists, and physical, occupational, and speech therapists have recommended their participation. This expanded presence has led many researchers to investigate the effect that animals have within the medical field. Despite the recent emergence of pet therapy, with the first reported use occurring less than 100 years ago, there have already been reports of the positive outcomes that these animals have on humans receiving healthcare services.
The origin of therapy animals dates back to the 1930s, when Dr. Sigmund Freud brought his own dog, Jofi, to psychotherapy sessions to interact with his patients. Freud found that his patients were more likely to comply with the therapy, divulging more information to the dog than they would to Freud himself.23 Dr. Boris Levinson had a similar experience with his dog, Jingles, and was named the father of animal-assisted therapy when he wrote his book Pet-Oriented Psychotherapy. In this text, he states that when his patients communicated through Jingles, they had psychologically therapeutic breakthroughs.24 These findings have fostered the use of therapy animals in healthcare settings such as nursing homes, hospitals, and outpatient clinics.25 Not only do these animals assist with mental health, but they are now used in other disciplines, such as physical therapy occupational therapy, speech therapy, recreational therapy, and many others.26
According to the International Association of Human-Animal Interaction Organizations, animal-assisted intervention is an “intervention that intentionally includes or incorporates animals in health, education, and human service for the purpose of therapeutic gains in humans.”27 The field of animal-assisted intervention therefore includes the categories of animal-assisted therapy, animal-assisted education, and animal-assisted activities. All three of these programs, while promoting well-being and prosperity in humans, also need to provide a constructive encounter for the animal.28 When engaging in animal-assisted therapy, it is important for the handlers and providers to ensure that they are following professional guidelines. For the human participant, the provider needs to obtain informed consent while also following the proper intervention protocol. This includes doing a formal evaluation prior to the introduction of animal-assisted therapy, establishing both short-term and long-term goals, and properly evaluating the effectiveness of the interaction through progress measurement and documentation.29
In any healthcare interaction there are regulations that need to be followed to prevent harm and promote well-being for the patients. Some of these laws and regulations include the Health Insurance Portability and Accountability Act of 1996 and the American Nurses Association Code of Ethics for Nurses. These laws and ethical guidelines promote principles of autonomy, justice, and beneficence.30 While these regulations are extremely effective in protecting the human patient, they neglect to include provisions for the support animal that is being utilized in the field. To compensate, dog handlers are encouraged to be an advocate for their dog in every animal-assisted intervention. The handlers should respect the dog’s preferences on environment, population, activity, touch, and proxemics, or amount of space the animals choose to place between themselves and others.31 Dogs are similar to humans in that they have personal space preferences. They may react differently when a person moves into their space than when they move into a person’s space.32
Additionally, dogs need to be properly trained and professionally assessed in order to be correctly paired with a population or environment that best matches the animal’s skill set. Especially for therapy dogs, where the majority of their time is spent with their handler, the lifestyles of the dog and the human need to be coordinated. Specific traits that are assessed include activity level, personality, leisure activity, dog training, and skill level.33 Handlers should also undergo specific training regarding animal behavior and health in order to maintain the safety of both the animal and the human participating in the therapy sessions. The training and subsequent certification assessment covers topics related to zoonotic disease, infection control, and patient confidentiality. It also discusses whom to contact in case of an emergency, accident, or injury, and how to interpret an animal’s body language, specifically how to identify signs of discomfort, distress, and fear.34 When matching a dog to a specific patient population, it is important to consider the following: breed restrictions, client population demographics, client population treatment categories, psychiatric related issues, environmental setting, the presence of sensory sensitivities or distractions, how the dog will be utilized during the session, and work frequency requirements.35
Other traits that need to be noted and present in the dogs prior to the matching process include a robust personality, adaptability and flexibility, adequate responsiveness, secure attachment to the handler, self-motivation, quick recovery when startled, sociability, and a willingness to engage with the patients during the session.36 The dogs should have a natural curiosity toward the activities performed during the therapy sessions, and patience, especially when the clients are unable to complete certain activities.37
It is important to note that there are risks to the animals, and it is not uncommon that these animals face hardships and stressors as they engage in the work environment. Multiple research studies performed on therapy animals reported mixed results regarding the level of cortisol, known as the classic stress hormone, that was present after an animal-assisted intervention session. In some of the dogs, there was an increase in the cortisol level, indicating that the animals were distressed. However, it is currently unclear whether this reported stress was a result of positive excitement or affliction.38 These studies also reported that the animals did not display increased stress behaviors during the therapy sessions in comparison to their baseline. The mixed results may be related to the phenomenon known as the individuality feature. This feature suggests that each animal reacts differently to similar interventions, and “the stress an [animal-assisted intervention] may place on an animal is dependent on . . . the handler, the participant, the environment, and the interaction itself.”39 Therefore, it is unique each time.
Additionally, there have been reports of therapy animals becoming colonized with common hospital bacteria. These bacterial organisms are known to be difficult to treat, as they are often resistant to antibiotics and are therefore considered to be “superbugs.” Contracting these organisms in the healthcare setting is consistently a problem and poses multiple risks for the patients during their healing process. Activities such as paw shaking, lying on hospital beds, licking faces, and taking treats should be avoided, while vigorous hand washing with soap and water should be implemented, in order to limit the risk that the animals contract Clostridium difficile or methicillin-resistant Staphylococcus aureus (MRSA).40 Hand washing is proven to be the best risk mitigation strategy to prevent the transmission of microorganisms.
Since the late 1900s, healthcare research regarding animal-assisted interventions has been performed on a variety of populations of all ages in the hospital setting and in the outpatient setting, including those requiring speech therapy after suffering from aphasia. Healthcare workers themselves have even participated in studies aiming to reduce stress and patient-related burnout. These important findings, as well as future clinical indications, will be discussed below, such as how animal-assisted therapy reduces pain, and symptoms of various mental illnesses and disorders such as anxiety and depression, and improves language use in patients struggling with communication.
Several research studies involving animal-assisted therapy in the healthcare field have shown that it reduces the incidence of negative symptoms related to disease processes. In 2016, an article entitled “Effects of Animal-Assisted Activity on Self-Reported Feelings of Pain in Hospitalized Children and Adolescents” supported the use of therapy animals in the clinical setting. The participants in the study include seventeen male and female hospitalized children, all older than seven years, who had reported feelings of pain. The participants were asked to describe their pain both before and after interacting with the therapy dog, and the results were overwhelmingly positive, with a decrease in pain reported by almost all of the participants.41
In this study, prior to introducing the participants to the therapy dogs, a majority of the patients were lying in bed, with the windows closed. Some children even had the lights turned off to reduce stimulation. The study reports that as soon as the dog entered the patient’s room, the participants either got out of bed or sat up, asked to open the windows, and wanted the lights to be turned on if they were previously off. Additionally, the participants engaged in self-care, asking to have their hair brushed or their clothing changed.42 For those children who did not report a decrease in pain after the intervention, an improvement in affect and mood was reported. One caregiver reported “that the child was not motivated to talk that day,” but once the dog was brought to interact with the child, “the patient talked and smiled.”43 There was only one outlier in the study, a child who reported increased pain after the animal-assisted activity. This participant acknowledged that the abdominal pain was due to the “uncomfortable position . . . that they were in during the intervention,” as they were sitting upright in order to engage with the dog.44 This patient, even with an increase in discomfort after the interaction with the therapy dog, still had a positive overall experience, as he or she “interacted with the dog, pet him, smiled, and told stories about their own dog.”45
Although it is well known that the gold standard for pain is the patient’s report, there are other indicators that can aid healthcare providers in determining how much pain a patient is in. These are known as physiologic indicators of pain, and they include measures such as heart rate, blood pressure, body temperature, respiratory rate, and pupillary diameter. A reduction in pain is usually shown by a decrease in each of the aforementioned indicators, and the study reported this pattern occurring for their participants.46 When the animals were introduced to patients reporting pain, there was a reduction in the vital signs listed above, suggesting a decrease in pain stimuli.
Since hospitalization is an extremely stressful event, especially in children and adolescents, feelings of pain will be heightened due to anxiety. The study concluded that the animal-assisted activity had a positive psychological impact, with reports of enhanced mood, indicated by increased smiles, conversation, and sociability, as well as improved motivation, with participants getting out of bed more frequently. Lastly, there was a decrease in incidence of crying and feelings of depression.47 Distraction is a known non- pharmacologic treatment for pain, and the “positive friendships and affection” that exists between the child, the animal, and the handler “may act as a key . . .factor” as to why this type of therapy is effective.48 The participants focused their attention on the animals, since it is a positive stimulus, and their brains gave less attention to the negative healthcare-associated stimuli, or the pain they were experiencing.49
In August of 2020, another research article was published regarding the use of animals at the Pediatric Day Hospital of the A Coruña University Hospital Complex in Spain. The hospital consists of eight beds, twelve chairs, and a procedure room, as most patients come to the hospital from home for a treatment or procedure, remaining in the hospital for fourteen hours or less.50 Each session, directed by an occupational therapist, lasted no more than 30 minutes and occurred only once a week for six months using one of three medium-sized dogs: either a Labrador Retriever or a Golden Retriever.51 The dogs underwent an extensive training program prior to initiating the therapy sessions in order to develop obedience and a calm, friendly temperament.52
The activities conducted during the therapy sessions, when analyzed, were categorized into five groups: getting to know the animal, interacting with the animal, caring for the animal, playing with the animal, and the features of the animal-assisted therapy, where the therapist explained how therapy dogs are utilized and trained. The children performed tasks such as learning the dog’s breed and name, expressing thoughts or feelings to the dog, petting the dog, preparing the dog’s water and food, playing fetch with the dog, and learning about the benefits of animal-assisted therapy.53 Among the fifty-five children participating in the study, none felt uncomfortable, anxious, or fearful in the presence of the dog, and all stated that they liked the session “a lot,” with a rating of three out of three stars.54 Additionally, all of the participants’ caregivers rated the intervention as a ten on a scale of one to ten.55 The caregivers also stated that they saw a positive change in their child’s mood, with the children being “significantly more cheerful and relaxed, as well as less fearful and socially withdrawn.”56
As discussed earlier, the first recorded use of therapy animals was for psychotherapy to treat mental health disorders. In 2017, a systematic review was performed to analyze several clinical research studies performed on a wide range of mental health populations. The goal was to discover underlying trends in order to make a generalized statement about the use of animal assisted therapy for adolescents seeking treatment for mental disorders.57
One of the more common mental disorders is attention deficit hyperactivity disorder (ADHD). ADHD is a behavioral disorder characterized by inattention, hyperactivity, and impulsivity.58 A recent study analyzed how animal-assisted therapy impacted people who suffer from this mental disorder, and it revealed that through the use of therapy animals, ADHD symptoms are reduced.59 The manifestations of ADHD can be classified into three categories, according to the three major characteristics. Under inattention, patients often have a shortened attention span with trouble listening to others. They also tend to get distracted easily, are forgetful and disorganized, and lack attention to detail. Symptoms related to impulsivity include interrupting, impatience, and risk taking. Lastly, hyperactivity manifests as difficulty sitting still, frequent fidgeting, and difficulty focusing on one task, especially since this population tends to be excessively talkative.60 Through the unstructured interaction with the animals, children and adolescents with ADHD tended to have improved social skills and positive behaviors, while also displaying a decrease in some of the problem behaviors listed above.61
Another mental disorder that has been studied is post-traumatic stress disorder, otherwise referred to as PTSD. The systematic review discussed three articles featuring unstructured, independent activity with dogs, as well as semi-structured activity with horses. The participants were assessed for symptoms of anxiety, depression, anger, PTSD, dissociation, and insecure attachment prior to and following the animal therapy, and all three studies found significant improvements in the categories listed above.62
Animal-assisted therapy is most widely utilized in children with autism. These interventions include both equine and canine therapies.63 Laboratory based studies have reported that “children with [autism spectrum disorder] tend to prefer pictures of animals over humans and inanimate objects,” resulting in the increased use of therapy animals among this population.64 The activities conducted throughout the fourteen studies analyzed via systematic review include animal care, knowledge, and games, with a focus on targeting skills such as verbal communication, prosocial behavior, and sensory-motor skills.65 Parents and caregivers of these children reported increased social interactions in the presence of the animal, with an associated reduction in social isolation and self-absorption. Additionally, five of the studies indicated an increase in communication and language use following the animal-assisted intervention.66 The participants spoke to the animals directly and referred to them more frequently and for a longer duration in comparison to inanimate objects.67 Lastly, three of the research articles revealed diminishing problem behaviors, such as physical and verbal aggression, in the presence of the therapy animal.68
Although there is an abundance of literature related to the use of animal-assisted therapy with adolescents, the adult and geriatric populations cannot be overlooked, as they also receive inpatient healthcare services. Antepartum clients, who were hospitalized for pregnancy complications including preterm labor, preterm premature membrane rupture, hyperemesis, placenta previa, preeclampsia, and gestational diabetes, were investigated in 2014.69
Clients completed two surveys prior to and following the animal-assisted intervention related to symptoms of anxiety and depression. The Spielberger State-Trait Anxiety Inventory (STAI) is a forty item questionnaire that is highly reliable in identifying underlying anxiety in clients, and the Beck Depression Inventory (BDI) is a twenty-one question survey that has been widely utilized in the healthcare setting to detect depressive symptoms.70 During the eighty-two therapy sessions conducted, each participant received twenty minutes of independent in-room contact with a therapy dog.71 In both the BDI and the STAI, scores after pet therapy significantly improved, with clients reporting fewer symptoms of depression and anxiety.72
In the geriatric population, dementia is the most common cause of disability and requires an increase in healthcare services. Each year, the number of Americans diagnosed increases. Dementia manifests differently in each patient, since it has physical, psychological, social, and economic impacts. Currently, dementia is the seventh leading cause of death in the world.73 While there is no cure for dementia, recent research is focused on therapies to reduce or eliminate the negative symptoms that occur as a result of dementia, such as aggression, agitation, depression, anorexia, and a sedentary lifestyle.74 The animals utilized for dementia patients include dogs, fish, cats, and horses. Throughout all of the studies analyzed in the systematic review, there was a consistent decrease in the manifestation of agitation, with reduced physical or verbal outbursts, pacing, obsessive behavior, restlessness, and emotional distress. Sundowning is a common phenomenon among patients with dementia that refers to increased agitation with the onset of the night. One study in particular focused on sundowning behaviors and reported a significant decrease in evening agitation after animal-assisted interventions.75
Additionally, there were also many reports of participants having increased engagement, either with other humans, or with the animals, shown through physical contact, eye contact, and talking. Social interactions were measured by the length of time the participants spent leaning forward, as well as the frequency with which they smiled, engaged in tactile contact, and praised the animal.76 Disorientation also tends to increase as dementia worsens, leading to an increase in social isolation; however, after interaction with the therapy animals, the patients were reoriented and were better able to express themselves.77 Overall, dementia patients had an improved quality of life with a reduction in depressive symptoms, increase in physical activity, and increase in food consumption.78
Lastly, in the outpatient setting, a research study was conducted featuring clients receiving speech therapy due to aphasia. The study was very small in comparison to the others and consisted of three male participants who had suffered a left-hemisphere stroke, resulting in slow, effortful speech.79 Their participation in the outpatient speech therapy was to improve their language activity and achieve complete or near complete communication functionality. The speech therapist conducting the sessions had set goals for each participant during their first meeting, and by the end, each participant had met or exceeded the goals.80 All of the clients also described an increase in their mood when the therapy dogs were present, as they enjoyed the sessions more and looked forward to attending. Lastly, it was reported that the clients spoke with more effort when directing their communication to the clinician than when talking to the dog, indicating that the dog helped relieve anxiety and stress.81
There are several theories that explain the positive results seen throughout the studies discussed above. The field of anthrozoology, which is dedicated to “the mutual and dynamic relationships between people and animals,” uses a theory called the human-animal interaction theory to explain how animal-assisted therapy works. This theory suggests that humans tend to seek out animal contact as a source of calming and non-judgmental social interaction and support.82 Similarly, the biophilia hypothesis describes human beings’ inborn biological desire to create and maintain connections with other forms of natural life, especially with members of the animal kingdom.83 Animals are sentient beings, since they are able to feel emotions, experience pleasure, pain, and suffering, and be empathetic.84 The human-animal interaction results in increased prolactin, phenylethylamine, oxytocin, and dopamine production, all of which are hormones associated with bonding, pleasure, happiness, and love. Both dogs and humans are reported to have an increase in these hormones when interacting with one another, as well as improved immunity, seen by an elevated neutrophil, or white blood cell, count.85
Since animal-assisted therapy is a relatively new intervention in the healthcare setting, the need for additional research is more pressing than ever. The preliminary studies have shown the benefits that animals have on all people, with improved mood and reduced pain and symptoms of various health disorders, but any negative consequences may take time to become apparent. Additionally, the biological theories, although convincing, should be further analyzed in order to discover the mechanisms that result in the positive effects we currently see. Finally, the need to expand animal-assisted interventions to all populations in the healthcare field, as well as other fields, should be researched and implemented to promote human prosperity in general. The forthcoming research in animal-assisted therapy must seek to protect the well-being of the animal, with ethical standards integrated both into future studies and into the field as a whole. Furthermore, determining whether the work is distressing to the animal could assist our society in advancing and improving animal-assisted intervention. Therapy animals have the ability to improve human welfare, the healing process, hospitalizations, and other healthcare services, and therefore should be integrated into multidisciplinary teams.
