You won't believe these 10 facts about people. A catgut suture is a suturing material made from the collagen found in the intestines of animals. Sheep have historically been used as a source for catgut, although dogs and goats have been used as well.Despite the name, catgut sutures actually have nothing to do with cats.ou won't believe these 10 facts about people. A catgut suture is a suturing material made from the collagen found in the intestines of animals. Sheep have historically been used as a source for catgut, although dogs and goats have been used as well.