Suture Material for Cystotomy in Dogs and How It Changes Bladder Healing

Cystotomy in dogs is an incision into the urinary bladder, performed most often to remove bladder stones, and it is one of the most common surgical procedures in small animal surgery. The incision is simple to make and easy to underestimate to close. The bladder holds urine under pressure, the suture lies in direct contact with that urine, and suture material has been linked to urolith recurrence.

The short answer is a synthetic absorbable monofilament suture, placed full thickness with secure knots. This article sets out what a university surgeon's review says about closing the bladder, how the choice of suture material changes healing, and which materials in the Gexfix range match those requirements. It also covers the limits, because suture material cannot compensate for stones left behind and not every closure pattern suits every bladder wall.

What Is Cystotomy in Dogs?

Cystotomy in dogs is a surgical incision into the bladder, most often made to remove uroliths. Dog surgery for bladder stones is the usual reason for the operation, and the procedure ends when the bladder wall is closed so that it holds urine while the tissue heals. The quality of that closure determines whether urine leaks into the abdomen and whether the lumen stays open. The Merck Veterinary Manual states that cystoliths can be removed by cystotomy, and that nonsurgical techniques are preferred when possible because of the risk of suture-induced urolith recurrence. Bladder stones in dogs are therefore a reason to choose the suture with care.

Where Absorbable Suture Fits

A bladder closure is an internal soft tissue closure, and internal closures use absorbable material that disappears once the tissue has regained its own strength. The wider role is covered in the guide to the role of absorbable sutures in veterinary soft tissue surgery. The bladder adds two conditions of its own, which are constant urine contact and a very short healing window.

Feline Cystotomy

Feline cystotomy also depends on a leak-tight closure with material that does not remain in the bladder. The Merck Veterinary Manual covers urolithiasis in both dogs and cats, but the retrospective figures later in this article come from dogs and are not applied to cats.

Why Suture Material Matters in the Bladder

A Short Healing Window

The review states that the urinary bladder regains nearly 100% of its original tensile strength by 14 days. The suture has to hold reliably for about two weeks, not for months.

Absorption time is a different measurement from holding time. The Gexfix Product Reference lists PGA at about 60 to 90 days, PGCL at about 90 to 120 days, chromic catgut at 90 to 120 days and PDS at about 180 to 210 days. Every one of those absorption windows is longer than the 14 days the bladder needs. A longer window is therefore not an advantage in the bladder, and the practical question becomes how the material behaves while it is present. The page on PGCL suture absorption time explains how the absorption figure should be read.

Urine Contact and Stone Formation

The review states that monofilament suture is preferred because there is some concern that contact between urine and multifilament suture may lead to an increased rate of absorption. It also states that urinary calculi formation has been associated with multifilament absorbable suture, nonabsorbable suture and metal staples. Nonabsorbable suture and staples are described as contraindicated in urinary bladder closure.

The evidence has a gap, and the review names it directly. There have been no studies assessing the lithogenic potential of the newer monofilament absorbable sutures. The preference for monofilament is therefore a reasoned preference, not a proven reduction in stone recurrence.

Monofilament and Braided Construction

Braided and twisted materials have crevices that a smooth monofilament does not. The wider comparison is set out in the guide to braided versus monofilament suture. For the bladder, the review settles the question in favour of monofilament, and the Gexfix handling notes point the same way where infection is a concern.

How Closure Pattern and Bite Depth Affect Sealing

Closure Patterns

The review lists four closure patterns for the bladder: single-layer simple interrupted, single-layer simple continuous, two-layer appositional continuous and two-layer inverting continuous. It reports no difference in circular bursting wall tension between single-layer simple interrupted and two-layer inverting closures, and clinical outcomes are similar between them. Pattern choice therefore follows the bladder wall, not a search for a stronger pattern.

The wall matters because luminal compromise may occur if two-layer inverting patterns are used in bladders with severely thickened walls. The review's author prefers a single-layer, full-thickness, simple continuous pattern for a simple cystotomy.

Bite Depth and Spacing

A full-thickness bite includes the submucosa, which is the holding layer of the bladder wall. The review states that partial-thickness single-layer closures that miss the submucosa may be inadequate for preventing urine leakage. For the preferred pattern, it places bites 3 mm apart and 3 mm from each edge, incorporating all layers, and ties each knot with 5 to 6 throws.

The Product Reference describes PGCL knot security as slightly less forgiving than braided PGA, and it advises planning extra throws with PDS.

Matching Absorbable Materials to Bladder Closure

The Gexfix Product Reference does not name cystotomy as an indication for any suture, so the table pairs manufacturer properties from the Product Reference with the requirements stated in the review. The final row is the comparison that matters for this procedure.

On these figures, two materials meet both requirements of the review, which are absorbable and monofilament. They are PGCL MONOFIL® and PDS. Because the bladder regains its strength in about 14 days, long tensile support is not the deciding factor between them. The practical differences are handling and knots. PGCL passes smoothly with minimal tissue drag, while PDS is stiffer and calls for extra throws. The detail behind that stiffness is described in the article on polydioxanone suture absorption time and strength.

Chromic catgut and braided PGA remain useful elsewhere in the abdomen, but the review ties multifilament absorbable material to calculi formation. Catgut also loses strength beyond about 2 to 3 weeks, which sits close to the 14 day healing window and leaves little margin if a bladder heals slowly.

When Absorbable Monofilament Is NOT the Appropriate Choice

The Rest of the Incision

The bladder is closed with one material, but the abdomen is closed with several. The Product Reference positions PDS for fascia and slow-healing or high-tension tissue, and polyamide for skin and external closures where removal is planned. The guide to polyamide nylon suture explains when non-absorbable material is the right choice. Polyamide has no place in the bladder wall, but it can be correct in the skin of the same patient.

When Stones Remain

No suture prevents a stone that was never removed. The review states that cystotomy failure occurs in up to 20% of cases, and the review defines that failure as stones left behind in the bladder or urethra. A published review of 128 dogs that underwent cystotomy found that effectiveness could be determined in 44 dogs, and 9 of those 44 (20%) had incomplete removal of uroliths. Appropriate postoperative imaging was performed for only 19 dogs (15%), and 8 of those 19 had incomplete removal. These figures describe retained uroliths, not suture failure. A technically perfect closure over a retained stone still leaves a patient with bladder stones, so the thoroughness of the stone search and the postoperative imaging carry more weight for that outcome than the choice of material. The surgeon's review advises postoperative abdominal radiographs to document complete stone removal.

When the Bladder Wall Is Severely Thickened

Where the wall is severely thickened, a two-layer inverting closure can narrow the lumen, so a single-layer pattern is chosen once the wall has been assessed. The material stays absorbable and monofilament.

Choosing a Suture for Cystotomy in Dogs

The requirements for cystotomy in dogs are narrow. The material should be synthetic, absorbable and monofilament, placed full thickness with knots that hold. Healing is quick, so a very long absorption window adds nothing, and the choice between PGCL and PDS comes down to handling. The honest limits are the missing data on newer monofilaments and the stones that remain in up to 20% of cases. Nonabsorbable suture and staples have no place in the bladder.

Gexfix International Corp., in partnership with Assut Europe S.P.A., supplies PGCL MONOFIL® monofilament sutures across the full range of USP sizes and needle configurations for veterinary practice. The complete suture range also includes ASSUFIL® PGA, ASSUFIL® PDS monofilament, ASSUCROM® Chromic Catgut, ASSUNYL® and FILBLOC® Barbed Sutures. With over 30 years of manufacturing expertise and ISO 13485-certified production standards, Gexfix provides veterinary practices with the reliable monofilament absorbable sutures and full suture portfolio that consistent outcomes require.

Explore the full range at medicaldevicevet.com.

Sources

MSD Veterinary Manual (Merck & Co., Inc.), Overview of Urolithiasis in Small Animals (2025). Veterinary reference text, written by a diplomate of the American College of Veterinary Internal Medicine at Iowa State University and peer reviewed. Published by Merck & Co., Inc., a pharmaceutical company, with no suture manufacturer funding stated. Supports the statement that cystoliths can be removed by cystotomy and the risk of suture-induced urolith recurrence.

Colorado State University (MacPhail C.), A Simple Cystotomy May Not Be So Simple (2022). Conference proceedings, LAVC Annual Conference Lima, published on IVIS on 3 March 2023. The author is an Associate Professor of Small Animal Surgery at Colorado State University, and no funding or sponsor was stated on the page. Supports the 14 day healing figure, the material preference and contraindications, the closure pattern findings, the bite and throw figures and the cystotomy failure rate.

Journal of the American Veterinary Medical Association (Grant D.C., Harper T.A.M., Werre S.R.), Frequency of incomplete urolith removal, complications, and diagnostic imaging following cystotomy for removal of uroliths from the lower urinary tract in dogs: 128 cases (1994-2006) (2010). Peer reviewed journal article, read through its record on the University of Illinois research portal. No funding statement was shown on that page. Supports the retained urolith and postoperative imaging figures.

Absorption windows, handling notes and infection field guidance come from technical data supplied by Gexfix International Corp. and Assut Europe S.P.A. and are manufacturer information.

FAQs

Q. What is cystotomy in dogs and why does suture material matter?

A. Cystotomy in dogs is an incision into the bladder, most often to remove stones. Suture material matters because the bladder regains nearly 100% of its original tensile strength by 14 days, and the suture sits in urine for that period. The review prefers synthetic absorbable monofilament and describes nonabsorbable suture and staples as contraindicated.

Q. Which suture is used for cystotomy in dogs?

A. The review states that synthetic absorbable material is most suitable, with monofilament preferred. In the Gexfix range, PGCL MONOFIL® and PDS meet both conditions. Multifilament absorbable suture has been associated with urinary calculi, so braided PGA and twisted catgut are not matched to the bladder.

Q. Does the closure pattern change how a bladder heals?

A. The review reports no difference in circular bursting wall tension between single-layer simple interrupted and two-layer inverting closures, with similar clinical outcomes. Full-thickness bites matter more for sealing, because partial-thickness closures that miss the submucosa may not prevent urine leakage. A two-layer inverting pattern can narrow the lumen in a severely thickened wall.

Q. Can bladder stones come back after cystotomy?

A. Yes, and suture material is one reason the Merck Veterinary Manual gives for preferring nonsurgical removal where possible, because of the risk of suture-induced urolith recurrence. Stones left behind are a separate problem. They occur in up to 20% of cases in the surgeon's review, which advises postoperative abdominal radiographs, and a published review of 128 dogs found appropriate postoperative imaging in only 15%.

Q. What should be expected after cystotomy in dogs?

A. The review states that pollakiuria and haematuria are expected for 3 to 5 days after surgery, and that the patient is typically recovered without a urethral catheter in place. The stone search at surgery and postoperative imaging matter as much as the closure.