CLINICAL QUESTION

Does pet therapy improve anxiety?

EVIDENCE-BASED ANSWER

Pet therapy is used to treat anxiety because it notably reduces self-reported anxiety across multiple age groups. (Strength of Recommendation [SOR]: A, meta-analysis of randomized controlled trials [RCTs], controlled trials, and observational studies.) Most pet therapy studies involve dogs, but cats and horses also have been studied. In patients with dementia, animal-assisted therapy reduces behavioral and psychological symptoms of dementia and depression. (SOR: A, meta-analysis of RCTs.)

EVIDENCE SUMMARY

A 2018 meta-analysis of 10 RCTs, 10 non-RCTs, and eight observational studies (N = 1,310) examined the effect of exposure to pet therapy on self-reported stress and anxiety scores across all ages and health statuses.¹ Twenty-three studies included adults (n = 1,225) and five studies included children (n = 85). Patients with anxiety or anxiety-associated diagnoses were seen in various settings, including outpatient, inpatient, and residential. Measurements were obtained immediately before and after pet therapy and included observed physiologic metrics and self-scoring indicators of stress and/or anxiety. Dogs were used in most studies, but two included cats.

In data pooled from the 28 studies, pet therapy produced a moderate decrease in self-reported anxiety (effect size = −0.50; 95% CI, −0.63 to −0.37). Key limitations were that most of the data were from observational or exploratory studies and anxiety measurement methods were highly variable.

A 2022 meta-analysis of 11 RCTs (N = 825) examined the effects of animal-assisted therapy using behavioral and psychological symptoms of dementia for assessment.² Patients diagnosed with dementia were exposed to animals ranging from 10-minute visits twice weekly for 2 weeks to 1-hour sessions twice weekly for 8 months. In most trials, participants in the intervention groups interacted with dogs and in one trial the participants interacted with horses. Participants in the control groups did not receive animal-assisted therapy.

Using various validated tools to measure outcomes, results were pooled and converted to a standardized mean difference (SMD). In three trials, the animal-assisted therapy groups had significantly improved scores on problem behavior and neuropsychiatric inventory scales vs. the control groups (three trials; n = 418; SMD = −0.43; 95% CI, −0.62 to −0.23). In five trials, depression scores also vastly improved in the animal-assisted therapy groups vs. control groups (five trials; n = 497; SMD = −0.50; 95% CI, −0.68 to −0.32). A 2021 RCT (N = 47) studied the effectiveness of a single animal-assisted therapy session for patients in Poland who were being treated for anxiety disorder or mixed depressive-anxiety disorder.3 Patients (mean age = 34 years) were recruited from small group therapy sessions. Exclusion criteria included a fear of dogs, dog-related allergies, or a severe somatic condition, but no patients were excluded.

Twenty-one patients interacted with a dog during a short 15- to 20-minute walk with a dog and its handler, whereas a control group of 26 patients walked with a medical student or physician. Subjective anxiety was assessed using the State-Trait Anxiety Inventory, consisting of 20 state questions (“I am tense; I am worried” or “I feel calm; I feel secure”), rating each answer from “1 = not at all” to “4 = totally agree,” and 20 trait questions (“I worry too much over something that really doesn't matter” or “I am content; I am a steady person”), rating each comment from “1 = almost never” to “4 = almost always.” Questionnaires were given before the dog interaction and repeated immediately after. For the treatment group, postintervention scores for anxiety state were significantly lower than those for the control group (mean = 34 vs. 41; P < .001).