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. Although it would be theoretically possible to derive catgut from cats, the yield would not be very impressive when compared to that of a larger animal.
The origins of the term “catgut” appear to come from “kitgut,” a word derived from “kit” for “fiddle.” Kitgut fiddle strings were made from the processed intestines of animals such as sheep, and over time, the word was corrupted into “catgut.” Confusion about the term persists to this day, and inaccuracies about the source of the material used to make catgut have been perpetuated in numerous books, including supposedly authoritative histories.
Catgut has been used by humans for centuries. It is extremely durable and strong, and can be used to string musical instruments along with tennis rackets. For suturing, catgut is a popular material because it is absorptive, and it can be treated to render the material sterile. However, alternatives to collagen suture materials such as synthetic sutures and cotton sutures have gained popularity in many regions of the world, with catgut being primarily seen in the developing world because it is a cost effective suture material.
A basic collagen-based suture will absorb very quickly into the body, eliminating the necessity to remove the stitches. Chromic catgut sutures, treated with chromium salts, have a longer life, and can persist for up to 90 days. These sutures are chosen when a surgeon is concerned that a wound will not have time to heal before the regular sutures would be absorbed. In some cases, chromic catgut sutures may be removed once a surgeon is satisfied that a wound has healed, so the patient will not experience the itching and irritation associated with suture absorption while the sutures slowly break down.
The process to make this type of suture silk involves removing and scraping the intestines before soaking them in various chemicals for treatment, grading them, packaging them, and sterilizing them to ensure that no infectious material is present. Although it might seem odd to use intestines for sutures, by the time the treatment process is over, a catgut suture contains primarily collagen, and is quite far removed from its original state.