Vivisection means literally "to cut up something that's alive," and it's the term used for operating on live animals for scientific research. The word is usually used by people who oppose the practice.
You can see how the word would be an inflammatory way of describing experimentation on animals, as the root vivi-, meaning "alive," makes the practice sound all the more gruesome. Surgery on a (living) person would not be called vivisection. You can also use the word vivisection metaphorically, as you might write a review of a rap concert and perform a ruthless vivisection of the artist's rendition of "Somewhere Over the Rainbow."