The origin of the word catgut is very obscure; in fact the substance that it refers to is not made from cats at all. It is a tough cord with surprising tensile strength that is made from the intestines of herbivore-class animals like sheep or cows. It is used to make dissolving surgical sutures, the strings for instruments such as violins and other stringed instruments, tennis rackets and archery bows. A description of the process by which catgut is made can be found on the Britannica Online site, found here: http://www.britannica.com/EBchecked/topic/99465/catgut.
A sheep's intestinal tubes are removed then cut into ribbons and scraped to remove the muscular tissue that encircles the intestines and mucous membranes. The strands of intestine are then submerged in an alkaline bath before being stretched on a rack to dry.
In modern times, catgut strings for instruments such as violins are not entirely made of the sheep or cow intestines. The center of each string is made from catgut, but is then wrapped with one to three layers of copper or silver wire. According to The Violinist.Com, located here: http://www.violinist.com/wiki/violin-strings/, strings musicians like catgut strings because they provide a very rich sound that is warm with a lot of overtones. This type of string is preferred by musicians who play "traditional" classical music, particularly the Baroque style. The disadvantages of strings with a catgut core is that because they are a natural material, they are much more prone to shrink or stretch in response to changes in humidity or temperature. This causes the stringed instrument to require more frequent tuning than instruments strung with wholly metal strings.
Catgut sutures are used for applications where it does not make sense to have sutures that will need future removal, such as procedures that take place inside the body.
Though it has never been made from actual cats, catgut is an ancient material that is still widely used today.
Treatment of hyperlipemia by acupoint catgut-embedding in 34 cases.(Abstracts: The Journal of Traditional Chinese Medicine Abstracts September 2003)
Feb 01, 2004; 64 cases of hyperlipaemia were randomly divided into a Catgut-embedding group (34 cases) and a medication group (30...