I found this video showing how animals can make such a huge impact on people that are ill. Some of the best medicine comes with four legs and a wagging tail!
In this video, the dog Roscoe has the incredible ability to give voice to a man with Alzheimer's disease who has lost most of his verbal communication skills. When Roscoe is in the room, the man's ability to speak magically reappears.
According to The Alzheimer's Association, pet therapy dates back to the 1860s, though the positive impact of animals on their guardians wasn't studied in earnest until the 1980s.