Animal-assisted therapy (AAT) is a type of therapy that involves animals as a form of treatment. The goal of AAT is to improve a patient’s social, emotional, or cognitive functioning. Advocates state that animals can be useful for educational and motivational effectiveness for participants. A therapist who brings along a pet may be viewed as being less threatening, increasing the rapport between patient and therapist. Animals used in therapy include domesticated pets, farm animals and marine mammals (such as dolphins). The research literature states concerns about the poor quality of medical evidence underpinning AAT.
Wilson's (1984) biophilia hypothesis is based on the premise that our attachment to and interest in animals stems from the strong possibility that human survival was partly dependent on signals from animals in the environment indicating safety or threat. The biophilia hypothesis suggests that now, if we see animals at rest or in a peaceful state, this may signal to us safety, security and feelings of well-being which in turn may trigger a state where personal change and healing are possible 
Animals can be used in a variety of settings such as prisons, nursing homes, mental institutions, hospitals and in the home. Assistance dogs can assist people with many different disabilities; they are capable of assisting certain life activities and help the individuals navigate outside of the home.
As with all other interventions, assessing whether a program is effective as far as its outcomes are concerned is easier when the goals are clear and are able to be specified. The literature review identified a range of goals for animal assisted therapy programs relevant to children and young people. They include enhanced capacity to form positive relationships with others i-relief in pet ownership.
Therapists rely on techniques such as monitoring a child's behavior with the animal, their tone of voice, and indirect interviewing. These techniques are used, along with the child's pet or other animal, in order to gain information. Before pet therapy can be useful, the child and the animal must first develop a sense of comfort with each other, which is easier to achieve if the child's own pet is used. The applied technique that generates the most helpful information about the victim's experience is telling the child that the animal wants to know how they are feeling or what happened.
Pets may provide an opportunity for fun and relaxation for people in institutions.
Animal assisted therapy draws on the bond between animals and humans in order to help improve and maintain an individual's function and is being used to assist in the process of enhancing the individual's quality of life in nursing homes. Psychologists and therapists notice increasing unfavorable behaviors of elderly people that are transferred to nursing homes. Once the patients become settled into their new environment, they lose their sense of self-efficacy and independence. Simple, everyday tasks are taken away from them and the patients become lethargic, depressed, and anti-social if they do not have regular visitors.
When elderly people are transferred to nursing homes or LTC facilities, they often become passive, agitated, withdrawn, depressed, and inactive because of the lack of regular visitors or the loss of loved ones. Supporters of AAT say that animals can be helpful in motivating the patients to be active mentally and physically, keeping their minds sharp and bodies healthy. Therapists or visitors who bring animals into their sessions at the nursing home are often viewed as less threatening, which increases the relationship between the therapist/visitor and patient.
There are numerous techniques used in AAT, depending on the needs and condition of the patient. For elderly dementia patients, hands on interactions with the animal are the most important aspect. Animal assisted therapy provides these patients with opportunities to have close physical contact with the animals warm bodies, feeling heartbeats, caress soft skins and coats, notice breathing, and giving hugs. Animal assisted therapy counselors also plan activities for patients that need physical movement. These planned tasks include petting the animal, walking the animal, and grooming the animal. These experiences seem so common and simple, but elderly dementia patients do not typically have these interactions with people because their loved ones have passed or no one comes to visit them. Their mind needs to be stimulated in the ways it once was. Animals provide a sense of meaning and belonging to these patients and offer something to look forward to during their long days.
There are many types of AAT ranging from the use of dogs, to cats, even to small animals such as fish and hamsters. The most popular forms of AAT include Canine therapy, Dolphin therapy, and Equine therapy.
Dolphin assisted therapy refers to the practice of swimming with dolphins. Proponents claim for such encounters "extraordinary results of the therapy and breakthroughs in outcomes", however this form of therapy has been strongly criticised as having no long term benefit, and being based on flawed observations. Psychologists have cautioned that dolphin assisted therapy is not effective for any known condition and presents considerable risks to both human patients and the captive dolphins. Dolphin assisted therapy's agenda is to help people with autism, Down syndrome, and Cerebral Palsy with rehabilitation in motor function, speech, and language as well as to maintain and increase the client's attention span. The child has a one-on-one session with a therapist in a marine park of some kind. An ethical issue with data on dolphin-assisted therapy and the effectiveness of it is that most of the research is done by people who operate the dolphin-assisted therapy programs. Dolphin assisted therapy is an alternative medicine/therapy option for people who do not respond or are not keen on traditional medicines/therapies and it is a controversial therapy. John Lilly, who studied dolphin-human interaction, first considered this idea that interactions with dolphins can have rewarding benefits on humans in the 1960s. David Nathanson, who was a clinical psychologist, came up with much of the existing research on this therapy today. Nathanson's theory was that children with disabilities would increase their attention to related stimuli in the environment in hopes they would get to interact with the dolphins, helping motivate the child to do the task at hand and to give the appropriate responses according to that child's therapy program lessons 
A distinction exists between hippotherapy and therapeutic horseback riding. The American Hippotherapy Association defines hippotherapy as a physical, occupational, and speech-language therapy treatment strategy that utilizes equine movement as part of an integrated intervention program to achieve functional outcomes, while the Professional Association of Therapeutic Horsemanship International (PATHI) defines therapeutic riding as a riding lesson specially adapted for people with special needs. According to Marty Becker, hippotherapy programs are active "in twenty-four countries and the horse's functions have expanded to therapeutic riding for people with physical, psychological, cognitive, social, and behavioral problems". Hippotherapy has also been approved by the American Speech and Hearing Association as a treatment method for individuals with speech disorders. In addition, equine assisted psychotherapy (EAP) uses horses for work with persons who have mental health issues. EAP often does not involve riding. Additional information pertaining to equine assisted therapy can be seen with Laira Gold's open clinical study of EAT 
Evidence that dog visits confer health benefit to older people in residential care is methodologically weak, although some preliminary research suggests the effect may be on a par with that produced by visits from humans, or by time spent interacting with inanimate items.
There has been criticism as to the effectiveness of AAT. According to Lilienfeld and Arkowitz animal-assisted therapy is better considered a temporary fix. They point to the lack of longitudinal data or research to see if there is evidence for long term improvement in patients undergoing the therapy. They then suggest that this further supports the idea that AAT is more of an affective method of therapy rather than a behavioral treatment. They also state the dangers of these therapy programs in particular the Dolphin assisted therapy. Dolphin assisted therapy has not been shown to have significant results when dealing with a child's behavior. Instead Lilienfeld suggest that again animal assisted therapy might be a short term reinforcer, not a long term one. They also suggest that studies dealing with children should look into more balanced measures, such as having one group of children in the Dolphin group and the other in a setting where they still receive positive reinforcement. It is also suggested that DAT is harmful to the dolphins themselves; by taking dolphins out of their natural environment and putting them in captivity for therapy can be hazardous to their well being. There are not many quantitative studies about the impact of swimming with dolphins have on social behavior. Of the few studies, data has seemed limited or mixed in results. The first research on the effects of Dolphin-Assisted Therapy as a treatment was a case study by Betsy Smith in 1987. The dolphins were used to motivate a child with autism to communicate. Smith concluded that the use of Dolphin-Assisted Therapy has shown promising results on increasing attention spans and improved interaction and play behavior in the children. Other studies after concerning Dolphin Assisted Therapy yielded about the same results but failed to take into account other situational factors, what is also known as a confound, one or more effective ingredient in a study  that may have an impact on results in the study.
Another limitation of pet therapy also centers on the application during scenarios that involve adults who have been sexually assaulted. While pets do tend to cause more comfort to victims, pet therapy may not be the catalyst that provides positive success in therapy sessions. As mentioned above, adults tend not to focus as much on having an animal companion, and therefore, pet therapy cannot be attributed as the reason for success in those types of therapy sessions. Pet therapy does not raise any ethical concerns as far as advancing nonscientific agendas. On the other hand, there are some ethical concerns that arise when applying pet therapy to younger victims of sexual assault. For example, if a child is introduced to an animal that is not their pet, the application of pet therapy can cause some concerns. First of all, some children may not be comfortable with animals or may be frightened, so there would be ethical concerns with using pet therapy, which could be avoided by asking permission to use animals in therapy. Second, a special bond is created between animal and child during pet therapy. Therefore, if the animal in question does not belong to the child, there may be some negative side effects when the child discontinues therapy. The child will have become attached to the animal, which does raise some ethical issues as far as subjecting a child to the disappointment and possible relapse that can occur after therapy discontinues.
Sexual assault counselling
Applying pet therapy to victims of sexual assault can also reduce depression, anxiety, and other symptoms of post-traumatic stress disorder. Pet therapy promotes social interaction and is increasingly more accessible to those who already have pets. Victims of sexual assault are less likely to be anxious and are comforted by the presence of a companion that is offered through pet therapy. While there are other ways in which victims of sexual assault can receive therapy, the application of pet therapy does have a certain degree of success in these situations. For example, pet therapy helps the counselor and victim develop a positive alliance and a great sense of rapport more quickly. As mentioned before, the presence of a pet or other animal helps victims of sexual assault feel more comfortable in a therapy setting. The application of pet therapy in sexual assault cases has also contributed positively to victims outside of counseling sessions. The positive feelings that pet therapy induces during therapy sessions with sexual assault victims will carry over with victims outside of therapy. The increased comfort that having a companion builds will also help victims remain more comfortable from day to day, which will lead to fast recovery.
A 2014 study found that there was too little evidence to make any recommendations for the use of AAT to alleviate agitation in older people with dementia; only three studies had been done to date, with mixed results.
The AAT program encourages expressions of emotions and cognitive stimulation through discussions and reminiscing of memories while the patient bonds with the animal. Many of the troubling symptoms in elderly dementia patients include decreased physical functioning, apathy, depression, loneliness, and disturbing behaviors.
Animal-assisted therapy sprouted from the idea and initial belief in the supernatural powers of animals and animal spirits. It first appeared in the groupings of early hunter gatherer societies. In modern times animals are seen as "agents of socialization" and as providers of "social support and relaxation."  Though animal assisted therapy is believed to have begun in these early human periods it is undocumented and based on speculation. The earliest reported use of AAT for the mentally ill took place in the late 18th century at the York Retreat in England, led by William Tuke. Patients at this facility were allowed to wander the grounds which contained a population of small domestic animals. These were believed to be effective tools for socialization. In 1860, the Bethlem Hospital in England followed the same trend and added animals to the ward, greatly influencing the morale of the patients living there.
Sigmund Freud kept many dogs and often had his chow Jofi present during his pioneering sessions of psychoanalysis. He noticed that the presence of the dog was helpful because the patient would find that their speech would not shock or disturb the dog and this reassured them and so encouraged them to relax and confide. This was most effective when the patient was a child or adolescent. The theory behind AAT is what is known as Attachment theory.
Therapy involving animals was first used in therapy by Dr. Boris Levinson who accidentally discovered the use of pet therapy with children when he left his dog alone with a difficult child, and upon returning, found the child talking to the dog. However, in other pieces of literature it states that it was founded as early as 1792 at the Quaker Society of Friends York Retreat in England. Velde, Cipriani & Fisher also state "Florence Nightingale appreciated the benefits of pets in the treatment of individuals with illness. The US military promoted the use of dogs as a therapeutic intervention with psychiatric patients in 1919 at St Elizabeth’s Hospital in Washington, DC. Increased recognition of the value of human–pet bonding was noted by Dr. Boris Levinson in 1961".
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- Media related to Animal-assisted therapy at Wikimedia Commons