Sheep and Horses - Catgut is the name applied to cord of great toughness and tenacity prepared from the intestines of sheep, or occasionally from those of the horse, mule and ass. Those of the cat are not employed, and therefore it is supposed that the word is properly kitgut ("violin string"), kit meaning "fiddle," and that the present form has arisen through confusion with kit = cat.
The membrane is chemically treated, and slender strands are woven together into cords of great strength, which are used for stringing musical instruments such as the violin and the harp. Roman strings, imported from Italy, are considered the best for musical instruments. Catgut is also used for stringing tennis rackets and for some surgical sutures.