Pet therapy is a broad term for guided interactions between people and trained animals, used alongside conventional treatment to reduce anxiety, lower stress hormones, ease behavioral symptoms, and improve social functioning. Most programs use dogs, though horses, cats, and even robotic stand-ins have roles in specific settings. The practice goes by several formal names in the research literature, and the mechanisms behind it involve measurable hormonal shifts, not just the warm feeling of stroking a friendly animal. How well it works depends heavily on who the patient is, what the animal is trained to do, and how the program is structured.
What Counts as Pet Therapy
Professionals generally split the field into two categories. Animal-assisted therapy (AAT) is a structured, goal-directed intervention delivered by a licensed health professional with a trained animal as part of the treatment plan. The therapist sets specific clinical objectives, documents progress, and uses the animal intentionally to work toward those goals. Animal-assisted activities (AAA), by contrast, are more informal. Think of a volunteer bringing a certified therapy dog to a hospital ward so patients can pet and interact with it. AAA can improve mood and brighten a difficult day, but it lacks the individualized treatment goals of AAT.
A third category, psychiatric service dogs (PSDs), sits outside the therapy-visit model entirely. These are individually trained dogs that live with a person who has a diagnosed condition like PTSD, performing specific tasks such as interrupting panic episodes, creating physical space in crowds, or waking their handler from nightmares. The distinction matters because research findings from one category do not automatically apply to the others.
What Happens in Your Body During an Animal Interaction
The best-studied biological pathway involves two hormones: oxytocin (sometimes called the bonding hormone) and cortisol (the primary stress hormone). When people pet or interact with a dog, oxytocin levels tend to rise while cortisol drops. Research has documented that stroking a dog for as little as five minutes triggers a measurable increase in plasma oxytocin and other feel-good neurochemicals including dopamine in both the person and the dog. Quiet reading, used as a control condition in several of these studies, does not produce the same changes.1Frontiers in Psychology. Psychosocial and Psychophysiological Effects of Human-Animal Interactions: The Possible Role of Oxytocin
The cortisol reduction has been replicated in multiple contexts. Healthcare professionals who spent 20 minutes with a therapy dog showed a significant drop in both blood and salivary cortisol compared to those who simply rested quietly. Dog owners interacting with their own dogs saw cortisol fall, and even petting an unfamiliar dog produced a similar decrease.1Frontiers in Psychology. Psychosocial and Psychophysiological Effects of Human-Animal Interactions: The Possible Role of Oxytocin In a clinical trial with patients who have borderline personality disorder, sessions involving animals led to a significant reduction in cortisol alongside a modest (though not statistically significant) rise in oxytocin.2Journal of Psychiatric Research. Effects of human and animal-assisted skills training on oxytocin und cortisol levels in patients with borderline personality disorder
These hormonal shifts help explain why being around a calm, friendly animal can make you feel noticeably less tense. They also suggest the effect is not purely psychological: your endocrine system is responding to the interaction in ways you can measure in a lab.
Why Humans Are Drawn to Animals in the First Place
Some researchers frame pet therapy’s effectiveness through what is called the biophilia hypothesis, the idea that humans have an evolved, deep-seated interest in other living things. Babies, regardless of their parents’ cultural background, are born paying disproportionate attention to animals compared to other stimuli. This built-in fascination appears to be a human universal, not something taught.3Frontiers in Psychology. Companion animals support human wellbeing and health: evolutionary, behavioral and physiological contexts Theories connecting attachment, social support, and biophilia have been proposed as integrated frameworks for understanding why the presence of an animal in a therapeutic setting can accelerate trust and openness between patient and therapist.4Human-animal interaction bulletin. Enactive Anthrozoology: Toward an integrative theoretical model for understanding the therapeutic relationships between humans and animals
The practical upshot is that the animal often functions as a social lubricant. A child who refuses to speak with a therapist may open up while brushing a dog. An older adult who has withdrawn from conversation may start narrating what the dog is doing. The animal creates a shared focus that lowers the emotional stakes of the interaction, and that dynamic appears to draw on something hardwired rather than learned.
Children in Hospitals and Emergency Departments
Pediatric settings have produced some of the most convincing randomized evidence for pet therapy. A 2025 randomized clinical trial in a pediatric emergency department compared children who received standard care with those who also got a therapy-dog visit. Children who interacted with the dog reported roughly twice the anxiety reduction compared to the control group, and nearly half of those children experienced a clinically meaningful drop in anxiety scores versus about a quarter of controls.5PubMed Central. Therapy Dogs for Anxiety in Children in the Emergency Department A Randomized Clinical Trial
Similar findings come from inpatient pediatric wards. In a study of hospitalized children, anxiety dropped significantly in both a pet therapy group and a comparison group, but the children who received pet therapy experienced a significantly greater decrease.6Journal of Pediatric Nursing. The Effect of a Pet Therapy and Comparison Intervention on Anxiety in Hospitalized Children For kids, a hospital can be terrifying, full of unfamiliar adults, needles, and alarming sounds. A dog that wags its tail and nuzzles the child’s hand reframes the environment into something less threatening.
Autism and Social Functioning
For children and adolescents on the autism spectrum, AAT has shown promise across several dimensions including social interaction, emotional regulation, and behavior. A systematic review concluded that the emerging evidence points to positive effects in cognitive, social, emotional, behavioral, and physical domains, though the authors emphasized that more rigorous studies are needed.7Complementary Therapies in Clinical Practice. The effectiveness of animal-assisted therapy for children and adolescents with autism spectrum disorder: A systematic review
Horses, specifically, have attracted attention for this population. A systematic review of equine-assisted interventions for autistic children found improvements in social functioning, with early evidence suggesting those gains hold in the short and medium term after sessions end.8PubMed Central. Calm with horses? A systematic review of animal-assisted interventions for improving social functioning in children with autism Riding and caring for a horse demands nonverbal communication, attention to another being’s emotional state, and physical coordination, all areas where autistic children often benefit from structured practice.
Dementia and Older Adults
Behavioral and psychological symptoms of dementia, things like agitation, aggression, wandering, and depression, are among the hardest aspects of the disease for patients and caregivers alike. A systematic review found that dog therapy can serve as a beneficial complementary treatment for these symptoms across different levels of dementia severity, provided the sessions are targeted to individual needs.9PubMed Central. Effectiveness of the dog therapy for patients with dementia – a systematic review
In one study of older adults with dementia, AAT sessions led to statistically significant decreases in agitated behaviors and a significant increase in social interactions.10PubMed Central. Effects of animal-assisted therapy on agitated behaviors and social interactions of older adults with dementia A matched case-control trial in nursing homes added important nuance: in the group receiving standard care alone, agitation and depression worsened over 10 weeks. In the group that received AAT alongside their usual treatment, those symptoms held steady rather than improving, but they did not deteriorate the way they did in the control group.11The American Journal of Geriatric Psychiatry. Animal-Assisted Therapy and Agitation and Depression in Nursing Home Residents with Dementia: A Matched Case–Control Trial In a disease where decline is expected, maintaining stability counts as a meaningful outcome.
Veterans and PTSD
This is an area where the evidence has grown rapidly. A meta-analysis combining nine studies found that partnership with an assistance dog had a large and clinically meaningful effect on PTSD severity scores. The trained tasks veterans found most helpful included managing hypervigilance, coping with intrusive memories, reducing exaggerated startle reactions, and handling physical reactivity after encountering trauma reminders.12PLOS ONE. Assistance dogs for military veterans with PTSD: A systematic review, meta-analysis, and meta-synthesis
A 2024 controlled trial comparing veterans who received a service dog with those on a waiting list found significantly lower PTSD symptom severity across every symptom domain, including intrusion, avoidance, mood, and arousal, at the three-month mark.13JAMA Network Open. Service Dogs for Veterans and Military Members With Posttraumatic Stress Disorder: A Nonrandomized Controlled Trial These are compelling results, but earlier reviews have cautioned that much of the prior evidence relied on self-report, lacked adequate controls, and could not separate the effect of the dog’s trained tasks from the general benefits of simply living with a companion animal.14PubMed Central. The study of service dogs for veterans with Post-Traumatic Stress Disorder: a scoping literature review The field is improving, but the honest picture is that stronger trials are only now catching up to the enthusiasm.
Equine Therapy for Physical Rehabilitation
Horseback riding as therapy occupies its own distinct niche because it engages the body differently from sitting with a dog. The rhythmic, three-dimensional movement of a horse’s gait closely mimics the human walking pattern, and riders must constantly adjust their balance, posture, and core muscles. A meta-analysis found improvements in balance and gross motor function scores across hippotherapy and therapeutic riding programs.15American Journal of Physical Medicine & Rehabilitation. Therapeutic Effects of Horseback Riding Interventions: A Systematic Review and Meta-analysis
Children with cerebral palsy have shown particular benefit. A systematic review and meta-analysis found statistically significant improvements in walking, running, and jumping abilities among children with cerebral palsy, as well as improved mobility in older adults and stroke survivors.16PubMed Central. Effects of Equine-Assisted Therapy: A Systematic Review and Meta-Analysis The physical benefits appear greatest with programs running multiple weeks at one or more sessions weekly, with gains seen in spasticity, muscle symmetry, posture, balance, and gait.17PubMed. The Efficacy of Equine-Assisted Activities and Therapies on Improving Physical Function
How Long Do the Benefits Last
This is one of the more honest weak spots in the field. A study of therapy-dog sessions for university students around exam time found large and immediate effects on stress, happiness, and energy levels. But when researchers checked in several hours later, the improvements had faded to small.18PubMed. Petting away pre-exam stress: The effect of therapy dog sessions on student well-being A single visit with a therapy dog appears to work like a powerful but short-lived mood reset. For lasting change, repeated sessions embedded within a broader treatment plan seem necessary, which is one reason structured AAT programs differ from casual animal-visit programs in their outcomes.
What About the Animals
A responsible discussion of pet therapy has to address the experience of the animals doing the work. Dogs in therapy settings can show stress signals like lip licking, yawning, and panting, behaviors that handlers and therapists sometimes miss or dismiss.19PubMed Central. Recognizing and Mitigating Canine Stress during Animal Assisted Interventions Interestingly, one study of therapy dogs in pediatric oncology found no significant rise in cortisol levels between baseline and therapy sessions, suggesting the visits were not inherently stressful. However, dogs that showed more stress behaviors also showed more affiliative behaviors like approaching and nuzzling, which means a dog can look engaged and friendly to observers while simultaneously experiencing some distress.20Applied Animal Behaviour Science. Physiological and behavioral effects of animal-assisted interventions on therapy dogs in pediatric oncology settings
A pilot study of therapy dogs during initial visits to a complex medical facility found that handlers’ perception of their dog’s stress correlated with the dog’s cortisol levels, and that overall, both dogs and handlers maintained their welfare across visits.21Frontiers in Veterinary Science. Therapy Dogs’ and Handlers’ Behavior and Salivary Cortisol During Initial Visits in a Complex Medical Institution: A Pilot Study The takeaway is that therapy work is not automatically harmful to dogs, but programs need attentive handlers who recognize when a dog needs a break. An overworked or stressed therapy animal is bad for the animal and likely less effective therapeutically.
Safety and Infection Control in Healthcare Settings
Bringing animals into hospitals raises legitimate concerns about infection. A literature review found wide inconsistency in how facilities handle this: among surveyed hospitals, anywhere from about 13% to 90% had no standardized policies for therapy animals. Only about a quarter required documentation that the animal was healthy, and a similar fraction permitted only registered therapy animals. Alarmingly, roughly 20% of handlers in one survey practiced no infection control at all, and 40% could not name a single disease that might pass between a dog and a patient.22PubMed Central. Risks Associated with Animal-Assisted Intervention Programs: A Literature Review
The actual transmission risk appears to be manageable with basic precautions. A study tracking bacterial exchange between therapy dogs and children found that one dog repeatedly transmitted bacteria to children, while a second dog did not transmit any. The researchers concluded that simple infection control measures, like hand hygiene and keeping the dog clean, can substantially reduce the risk.23Journal of Hospital Infection. Low risk of transmission of pathogenic bacteria between children and the assistance dog during animal-assisted therapy if strict rules are followed Best-practice recommendations emphasize that hospitals should establish strict infection prevention protocols with the ability to trace every animal-patient interaction, particularly given the lack of conclusive evidence ruling out zoonotic transmission entirely.24Frontiers in Veterinary Science. Canine-Assisted Interventions in Hospitals: Best Practices for Maximizing Human and Canine Safety
The Cost Argument
Pet therapy has an underappreciated economic dimension. A therapy dog visit in one hospital system was estimated at about €450, while the alternative for an uncooperative pediatric patient, involving restraint and anesthesia for an examination, ran to roughly €5,400–6,300.25PubMed. Hospital Dog—effective, patient-safe, side-effect-free, environmentally safe, cost-effective integrated medicine When a calm dog helps a frightened child hold still for a blood draw or an MRI, the savings extend well beyond the emotional. Fewer sedation events mean fewer medication risks, less staff time, and faster throughput.
Robotic Pets as Alternatives
Not every setting can accommodate a live animal. Allergies, infection risk in immunocompromised wards, cultural concerns, and logistics all create barriers. Robotic pets, soft, responsive mechanical animals that purr, blink, and react to touch, have been developed to fill that gap. A scoping review found that low-cost robotic pets improved mood, communication, social interaction, and feelings of companionship in older adults and people with dementia.26PubMed Central. Impacts of Low-cost Robotic Pets for Older Adults and People With Dementia: Scoping Review
A network meta-analysis directly comparing animal-assisted therapy with pet-robot therapy in dementia care found no significant difference between the two on agitation, cognitive function, or quality of life. The robotic option marginally outperformed standard care for agitation, but neither real nor robotic animals meaningfully improved cognition or depression in these patients.27Frontiers in Aging Neuroscience. Network meta-analysis of comparative efficacy of animal-assisted therapy vs. pet-robot therapy in the management of dementia For facilities that cannot bring in live animals, a robotic alternative is not a gimmick; it appears to offer comparable benefits for at least some outcomes.
What the Research Still Cannot Answer
For all the positive findings, the field has a transparency problem about its own limitations. A systematic review examining control conditions across AAI studies concluded that the research still cannot clearly answer how and why animal-assisted interventions work. Most studies implicitly treat the animal itself as the active ingredient but fail to adequately control for other factors: the extra human attention, the novelty of the experience, or the social interaction that comes packaged with the animal visit.28Frontiers in Psychology. Specific and Non-specific Factors of Animal-Assisted Interventions Considered in Research: A Systematic Review Sample sizes across much of the literature remain small, and study designs are diverse in ways that make comparisons difficult.29MINERVA PSICHIATRICA. Efficacy of animal assisted therapy on people with mental disorders: an update on the evidence Methodology has improved in recent years, but the field is still catching up to the standard expected in clinical medicine.
Cultural and Religious Considerations
Pet therapy programs developed largely in Western, dog-friendly cultures, and that context does not translate universally. Attitudes toward animals, and dogs especially, vary substantially across cultural and religious traditions. In some communities dogs are considered unclean, and a well-meaning therapy-dog visit could cause distress rather than comfort. Effective programs require assessing a patient’s background before introducing an animal.30Human-animal interaction bulletin. Multicultural Considerations in Animal-Assisted Intervention Beyond personal attitudes, access disparities also shape who benefits: therapy-animal programs tend to cluster in well-resourced institutions, and communities with fewer healthcare resources are less likely to encounter them.31PubMed Central. Assessing Cultural, Religious, and Trauma Influences in Human-Animal Interactions for Effective Animal-Assisted Counseling A program that works beautifully in a suburban children’s hospital may need significant adaptation, or a different animal entirely, in another context.
The Therapy Dog as a Third Participant
One emerging line of thought challenges the traditional view of therapy as a two-way relationship between patient and therapist. In dog-assisted therapy, the dog is not a passive prop; it initiates contact, responds to emotional cues, and shifts the dynamic of the room in ways neither the patient nor the therapist fully controls. Researchers have begun framing these sessions as genuinely triadic, with the dog acting as a third agent rather than a tool the therapist wields.32Theory, Culture & Society. Multispecies Interaction in Dog-Assisted Therapy Sessions This reframing matters practically: it means the dog’s temperament, preferences, and moment-to-moment behavior are not background noise but active ingredients in the therapy. A dog that gravitates toward a withdrawn patient, or that lies down calmly next to someone in distress, is making a therapeutic contribution that the handler can support but not script. Recognizing the animal as a participant, not a piece of equipment, shapes how programs select, train, and protect their therapy animals.