Companion animals and human health: benefits, challenges, and the road ahead for human-animal interaction.

There is ample evidence that human-animal interaction (HAI) is associated with health. Studies encompass three general categories: those that compare companion animal owners with individuals who do not own companion animals, those examining brief, 'one-off' contacts with animals, and those that review animal-assisted interventions. The health benefits demonstrated typically include reductions in depression and loneliness, while enhancing social interaction or social skills, and decreasing anxiety and arousal. Other health benefits associated with companion animals include the promotion of exercise or physical activity. The types of human-animal contact that have been evaluated include visual contact, physical contact, and looking at images of animals. The species used in interventions include dogs, cats, horses, rabbits, goats, hamsters and crickets. Despite these benefits, HAIs are also associated with problems, including allergies, asthma, zoonoses, animal bites and scratches, and human falls. Other problems include grief and negative emotions when a companion animal is injured or dies. Companion animal ownership is also expensive. Inconsistent policies concerning keeping animals in housing and enabling service animals to access public places make it difficult to live with companion animals or keep service animals in some circumstances. Additional research is needed to provide an evidence base to evaluate the efficacy of particular types of HAI using a given type of animal. This will document specific outcomes for an individual with certain characteristics and assist in promoting the future use of HAI to enhance human and animal health and well-being.