English
Español
Français
Português
Русский
العربية
Deutsch
Türkçe
Bahasa Indonesia
Tiếng Việt
ไทย
简体中文
Catgut Sutures
Catgut is an absorbable suture material made from purified collagen taken from the intestinal submucosa of ruminants, formed into a twisted strand. It is the only suture material in general use that is broken down by the body's proteolytic enzymes rather than by hydrolysis.
Why it matters
Every synthetic absorbable suture is broken down by water reaching the polymer, a mechanism that belongs to the material. Catgut is a protein and is digested by the patient's own enzymes, so part of its behaviour belongs to the patient's inflammatory response rather than to the strand. That single mechanistic fact is what a clinician is reasoning about whenever catgut is compared with a synthetic, and it is why its figures are read differently.
The one material the body digests
Catgut is the oldest absorbable suture material still in use and the only one that is not a synthetic polymer. It is collagen — the structural protein of connective tissue — taken from the intestinal submucosa of ruminants, purified, and formed into a strand. The name is a historical accident and has never had anything to do with cats.
Everything that distinguishes catgut follows from being a protein. Synthetic absorbable sutures are polyesters, and polyesters are cleaved by water: the mechanism is hydrolysis, it needs nothing from the patient except a wet tissue bed, and it is a property of the material. Collagen is not cleaved by water in any useful sense. It is digested by proteolytic enzymes — the patient’s own — which means catgut’s absorption is coupled to the patient’s inflammatory and enzymatic activity in a way no synthetic’s is.
That is the spine of any comparison between catgut and a synthetic, and it is worth stating plainly what it is and is not. It is a difference in mechanism. Part of catgut’s behaviour is contributed by the patient rather than specified by the manufacturer, which is a genuine and clinically relevant thing to know before reading any figure in the instructions for use. It is not, on its own, a statement that either material performs better than the other.
Plain and chromic
Catgut is supplied in two forms. Plain catgut is the untreated strand. Chromic catgut is treated with a chromium salt solution, which cross-links the collagen and alters the way the strand resists enzymatic attack. The chromicising is carried out before the strands are spun, which is what allows the chromic content to be controlled evenly along the strand rather than applied to a finished one.
The two are different products with separate specifications, stated separately in their instructions for use. Plain catgut is ivory in colour; chromic carries its characteristic brown. Dolphin Sutures manufactures both, as Progut Plain and Progut Chromic.
Construction, packing and sterilisation
Catgut’s construction is a third thing that sets it apart. Synthetic absorbables are either braided multifilaments or extruded monofilaments; catgut is neither. It is twisted, then ground to a uniform diameter and polished. The processing is a consequence of starting from a biological membrane rather than a spool of extruded polymer.
So is the packing. Catgut is supplied in isopropyl alcohol rather than dry — again because it is collagen — and it is sterilised with a fluid containing ethylene oxide, distilled water and isopropyl alcohol. Both are properties of the material class, and both are covered in the instructions for use supplied with the product.
One practical point sits outside the chemistry entirely. Catgut is animal-derived, and natural-origin suture materials are not uniformly available across markets. Before it is specified, the question is whether it is approved and supplied where the procedure takes place.
– Read more about catgut sutures manufactured by Dolphin Sutures
Key terminology
- Collagen
- The structural protein catgut is made of. Being a protein rather than a synthetic polyester is the reason it is absorbed enzymatically.
- Submucosa
- The connective-tissue layer of the intestinal wall from which the collagen used for catgut is taken. The name "catgut" is historical; cats have never been the source.
- Enzymatic (proteolytic) absorption
- Breakdown of a protein by the body's own enzymes. This is catgut's absorption mechanism, and it is coupled to the patient's response in a way hydrolysis is not.
- Plain catgut
- Catgut supplied without chromic treatment. It is the untreated form of the strand.
- Chromic catgut
- Catgut treated with a chromium salt solution, which cross-links the collagen and alters how the strand resists enzymatic attack. Chromicising is carried out before the strands are spun.
- Twisted construction
- Strands laid together by twisting rather than braiding or extrusion. It is the construction catgut is supplied in, and it is distinct from both braided multifilament and monofilament.
- USP
- United States Pharmacopeia. Sets the gauge and tensile-strength requirements a suture must meet at each size. The European Pharmacopoeia (EP) sets a parallel standard.
Technical characteristics
- Origin
- Purified collagen from the intestinal submucosa of ruminants
- Construction
- Twisted strand, ground and polished to a uniform diameter
- Forms
- Plain catgut and chromic catgut (treated with chromium salt solution)
- Absorption mechanism
- Enzymatic (proteolytic) — the only absorbable suture material in general use not absorbed by hydrolysis
- Colour
- Plain catgut is ivory; chromic catgut is supplied in its characteristic brown
- Packaging
- Supplied in a fluid (isopropyl alcohol) rather than dry
- Sterilisation
- Sterilising fluid containing ethylene oxide, distilled water and isopropyl alcohol
- Dolphin brands
- Progut Plain (plain catgut) and Progut Chromic (chromic catgut)
- Strength retention & absorption period
- Stated in the instructions for use supplied with the product — these are product-specific and are not reproduced here.
- Indications
- Stated in the instructions for use. Catgut is not indicated for every tissue type; the IFU specifies the exclusions.
- Availability
- Natural-origin suture materials are restricted in some markets. Regulatory status varies — check the position in your own market.
- Standards
- Manufactured to meet the USP and EP requirements for absorbable surgical sutures
How it compares
| Material | Origin | Construction | Absorption mechanism |
|---|---|---|---|
| Catgut | Natural (purified collagen) | Twisted | Enzymatic (proteolytic) |
| PGA | Synthetic (100% glycolide) | Braided multifilament | Hydrolysis |
| Polyglactin 910 | Synthetic (glycolide/L-lactide copolymer) | Braided multifilament | Hydrolysis |
| Poliglecaprone | Synthetic (glycolide/caprolactone copolymer) | Monofilament | Hydrolysis |
| Polydioxanone | Synthetic (p-dioxanone) | Monofilament | Hydrolysis |
What clinicians weigh when selecting
A mechanism that is partly the patient's
Hydrolysis depends on water, which any tissue bed supplies. Enzymatic breakdown depends on the patient's proteolytic activity, which is a variable belonging to the patient. The relevant question is how much of the absorption behaviour you are willing to have depend on something outside the material.
Plain against chromic
Chromicising cross-links the collagen and changes how the strand resists enzymatic attack. The trade-off is stated in each product's instructions for use; the two forms are not interchangeable readings of one specification.
The tissue bed
Because the mechanism is enzymatic, the character of the field is part of the question in a way it is not for a synthetic. This is a judgement about the case rather than a property of the strand.
Natural origin and market access
Catgut is an animal-derived material and its regulatory status is not uniform across markets. The relevant question before specifying it is whether it is available and approved where the procedure takes place.
Handling a fluid-packed strand
Catgut is packed in isopropyl alcohol rather than dry, which is a consequence of the material being collagen. How the strand is handled on opening follows from that, and the instructions for use covers it.
Frequently asked questions
Is catgut made from cats?
No — it never has been. The name is historical. The material is purified collagen taken from the intestinal submucosa of ruminants such as sheep or goat.
How is catgut absorbed, and why does that matter?
By the body's proteolytic enzymes, because it is a protein rather than a synthetic polyester. Every other absorbable suture in general use is broken down by hydrolysis — reaction with water. It is the one material where part of the absorption mechanism belongs to the patient's response rather than to the strand.
What is the difference between plain and chromic catgut?
Chromic catgut is treated with a chromium salt solution, which cross-links the collagen and alters how it resists enzymatic attack. The chromicising is done before the strands are spun. The resulting profiles are stated separately in each product's instructions for use.
How long does catgut take to absorb?
The absorption period is product-specific and is stated in the instructions for use supplied with the product. It is also the material whose absorption is most closely coupled to the patient's own enzymatic response, which is a further reason not to quote a general figure.
Why is catgut packed in fluid?
Because it is collagen rather than a synthetic polymer. It is supplied in isopropyl alcohol rather than dry.
Is catgut available everywhere?
No. Natural-origin suture materials are restricted in some markets, and the regulatory position differs. Check the status in your own market and consult the instructions for use supplied with the product there.
Instructions for use
The instructions for use supplied with the product is the controlled document for indications, contraindications, strength-retention and absorption data, warnings and precautions. Where this article and the instructions for use differ, the instructions for use govern. Approved indications vary by market, and this applies with particular force to natural-origin materials.
Medical & regulatory notice
This article is general reference information about a suture material for healthcare professionals. It is not medical advice, not a recommendation for any procedure or patient, and not a substitute for the instructions for use supplied with the product or for clinical judgement. Product availability and approved indications vary by market. Dolphin Sutures manufactures surgical sutures; nothing here should be read as a claim of clinical benefit or of superiority over another material.