A therapy dog is a dog trained to provide affection and comfort to people in hospitals, retirement homes, nursing homes, schools, hospices, people with learning difficulties, and stressful situations, such as disaster areas.

Therapy dogs come in all sizes and breeds. The most important characteristic of a therapy dog is its temperament. A good therapy dog must be friendly, patient, confident, gentle, and at ease in all situations. Therapy dogs must enjoy human contact and be content to be petted and handled, sometimes clumsily.

A therapy dog's primary job is to allow unfamiliar people to make physical contact with it and to enjoy that contact. Children in particular enjoy hugging animals; adults usually enjoy simply petting the dog. The dog might need to be lifted onto, or climb onto, an individual's lap or bed and sit or lie comfortably there. Many dogs contribute to the visiting experience by performing small tricks for their audience or by playing carefully structured games. In hospice environments, therapy dogs can play a role in palliative care by reducing death anxiety.