Catgut Absorbable Sutures

**Catgut** is a traditional absorbable suture material made from the serosa and submucosa of sheep or cow intestine — never from cats. The name is probably a corruption of 'kitgut' (kit was an archaic word for a fiddle, and the same animal-intestine material was also used for musical instrument strings). By the time the etymology had drifted, the false association with cats was fixed. ## How it works Catgut is almost pure collagen. When placed in living tissue, the body's proteolytic enzymes (especially collagenases and proteases from inflammatory cells) progressively digest the strand: - **Plain catgut**: digested in ~7-14 days. Used where fast absorption is wanted. - **Chromic catgut**: treated with chromium salts to cross-link the collagen. Digested in ~60-120 days. Used where longer tensile strength is needed. By the time the wound heals, the suture is gone. No removal step required — the central advantage of absorbable sutures for internal tissue. ## Historical use - **Galen** (2nd century AD): used catgut for internal sutures at the Galen at Pergamon Gladiator School. Linen or silk for external (removable). This absorbable-vs-permanent distinction is still the core choice in modern surgery. - **Andreas Vesalius** (16th c.): adopted catgut for vascular work. - **Joseph Lister** (19th c.): introduced carbolic acid sterilization of catgut. Catgut was implicated as a tetanus vector through much of the 19th century; sterilization and later chromic treatment substantially reduced infection rates. ## Ancient problems Until the 20th century, catgut had several issues: - **Not sterile**: contaminated with sheep gut flora, including Clostridium tetani spores. This contributed to post-surgical tetanus outbreaks. - **Variable absorption rate**: inconsistent batch-to-batch digestion, partly why chromic treatment was developed. - **Strong immune response**: because it is foreign animal protein, catgut triggered inflammation, sometimes excessive. - **Limited tensile strength**: weaker than modern synthetic absorbables. ## Other traditional suture materials - **Linen, silk**: non-absorbable, external use. Still used in modern surgery (especially silk for cardiovascular work where handling characteristics matter). - **Horsehair**: used for delicate facial closure. - **Animal tendon**: crushed tendon was sometimes used. - **Gold wire**: for high-value cosmetic or eye surgery, biocompatible, inert. - **Ant mandibles**: see Ant-Mandible Wound Closure — *Eciton* soldier ants' jaws used as biological staples in Ayurveda, Brazil, and parts of Africa. ## Modern replacements Catgut has been largely replaced by synthetic absorbables with more predictable properties: - **Polyglactin (Vicryl, Coated Vicryl)**: braided, ~60-90 day absorption - **Polyglycolic acid (Dexon)**: braided, ~60-90 day absorption - **Polydioxanone (PDS)**: monofilament, ~180+ day absorption for long-term strength - **Poliglecaprone 25 (Monocryl)**: monofilament, ~90-120 day absorption These are tested for predictable absorption rate, minimal inflammation, uniform strength. Catgut is banned in European Union surgical use since 2001 due to residual BSE concerns from bovine sources — synthetic replacements have been mandatory. ## Why the catgut story matters The principle Galen implemented — use an internal suture that the body eventually removes itself — is the foundational insight of modern absorbable suture design. Two thousand years of material improvements have not changed the core idea. The gap between Galen and the modern synthetic absorbables (Vicryl, 1974; PDS, 1980s) is ~90% sterilization improvements + 10% better materials. Galen's protocols with sterile modern suturing would approach modern survival rates for many wound types.