Irony here is that therapy dogs must have certification to visit patients in hospitals, extended care places and nursing homes. This is a requirement of the facilities they visit and I would assume be required by their insurance company to lessen liability.
Two of our dogs are certified therapy dogs. (Therapy Dogs International as well as Pals For Life) But first they had to pass their AKC good citizen tests. When they visit Alzheimer's patients at a extended care facility we have to provide proof of vaccinations, etc. as well as current certification.
The dogs were put through many tests including being around loud objects, a sit and stay when the handler walks out of the room, the 'bunny' test where the dog is supposed to ignore a rabbit in the cage, being around wheelchairs and crutches and some other distractions.