an antimicrobial treatment because bacteria adhere to them more than to monofilament (Chu and Williams 1984; Masini et al. 2011).
2.1.5 Rate of Strength Gain in GI Surgery
Under a normal healing environment, intestinal repair strength rapidly increases by the fifth day, and about 50% of strength return occurs by 10–14 days (see Chapter 1 for a review of intestinal healing). Since intermediate to prolonged absorbable sutures possess similar absorption rates (strength loss rate), they are preferred for most gastrointestinal repairs.
2.1.6 Suture Needles
Surgical needles are constructed of surgical grade stainless steel, and they have three basic parts, the suture attachment (swag), body, and needle point (Table 2.2). Needles chosen for use in gastrointestinal surgery are of the swaged‐on variety (permanently crimped to the suture material).
The body of needles used for most gastrointestinal surgeries are curved. The “flatter” curve of the 3/8 circle needle is best for suturing on surfaces that are superficial and readily exposed to the surgeon. Curved needles with great arc (1/2 and 5/8) are more suited for suturing small, deeper wounds in more confined areas.
Needle points can be divided into cutting, taper, or taper‐cut types. Cutting needles possess sharp points (two opposing cutting edges and a third edge along the outer curvature (reverse cutting) or the inside of the curvature (conventional cutting)). Both types of cutting needles are triangular on cross‐section, but the reverse cutting is most popular because it is 32% stronger, and it resists cut‐out during tissue passage due to the flat nature of the inner curvature. Cutting needles readily penetrate tough, heavily collagenous tissues such as gingiva. Taper point needles are round on cross‐section, and result in less tissue trauma, and smaller tissue punctures than cutting point needles. They are the preferred needle type for most gastrointestinal procedures. Taper‐cut needles combine the cutting action of the triangular shaped point, and the round body of the taper needle for atraumatic passage through delicate tissues. These needles are often chosen for mucogingival repairs, or when a friable tissue edge is sutured to tough skin or mucoperiosteum (Domnick 2014).
2.1.7 Directional Barbed Suture
Recently, use of directional or barbed suture materials have been documented in gastrointestinal procedures (Table 2.1) (Hansen and Monnet 2012; Erhart et al. 2013). Barbed sutures are manufactured by making small cuts in the surface of smooth suture, creating spurs. They are specifically designed to be used in continuous suture patterns. The barbs catch within collagenous tissue as each suture pass is taken. Unlike conventional sutures, previously placed tissue bites grab and remain secure in tissue, spreading tension throughout the line. Intestinal anastomosis performed with the unidirectional barbed suture seems to have a higher leakage pressure than anastomosis performed with regular monofilament sutures (Hansen and Monnet 2012). Each suture pass cannot “back out” due to the directional barbs. These sutures make it possible to secure a suture line without a knot. The suture is placed through a loop at the beginning of the suture line and then at the end of the suture line for gastrointestinal surgery two extra bites are made at 180° to lock the suture.
Barbed sutures have tensile strength comparable to their unbarbed equivalents when factoring size by their inner diameter at the depth of the barb cut versus outer diameter of conventional suture (Arbaugh et al. 2013; Ferrer‐Marquez and Belda‐Lorano 2009).
Both unidirectional suture and bidirectional sutures are available. Unidirectional sutures have a loop at one end and a needle on the other. The first needle bite is taken in tissue, and instead of creating a knot, the needle is passed through the loop to secure the end. With bidirectional barbed sutures, barbs are cut toward each end, starting mid‐strand with needles swaged on both ends.
Barbed sutures are more efficient to place than conventional sutures. They have been documented to reduce operative time and in some cases intraoperative bleeding, likely due to maintained consistent tightness throughout the continuous suture line. When used on hollow viscera, bursting pressures were comparable between barbed suture lines and conventional ones (Hansen and Monnet 2012; Erhart et al. 2013). Comparable outcomes following gastric, enteric, and biliary duct repairs using barbed suture have been reported (Denyttenaera et al. 2009). When using barbed suture for intra‐abdominal visceral repair, the exposed rough suture end from the final pass can create adhesion formation and possibly adjacent tissue erosion. It is recommended when terminating barbed suture placed for viscera, two final needle passes in opposing directions should be completed and the end should be cut short against the tissue to avoid excessive adhesion formation.
Table 2.2 Suture, staple recommendations for GI surgery in small animals.
| Tissue/Procedure | Suture Recommendations | Needle Recommendations | Suture Size Range | Stapling Equipment, Cartridge Size | Comments |
| Mucoperiosteal Flap, Cleft Palate, Oronasal Fistula Repair | Intermediate to prolonged absorbable suture; nonabsorbables are acceptable | Superficial closures 3/8 circle, deeper closures 1/2 circle; keratinized layers – reverse cutting or taper‐cut (skin, mucoperiosteum, gingiva); 5/8 circle needles may aid in suture placement for deep wounds in confined areas. | 5‐0 for small dogs and cat, 4‐0 larger animals | NA | Choose the smallest‐sized suture comfortably possible to minimize trauma from suture placement, and to reduce foreign body reaction. Removal of nonabsorbable sutures can be difficult from deeper regions of the mouth without sedation. |
| Gingiva, Oral Mucosa, Labial, Tongue Repair | Rapid to intermediate absorbable sutures | 3/8 circle, taper needles for mucosa; taper‐cut for gingiva | 5‐0 for small dogs and cat, 4‐0 larger animals | NA | Oral mucosa heals quickly. Be sure knots are firmly and squarely applied since knot ears have a tendency to untie prematurely particularly with multifilament absorbable sutures. |
| Esophagus/Anastomosis, Esophagotomy, Muscular Patch | Monofilament prolonged absorbable sutures | 3/8 to 1/2 circle taper needle. Deeper layers or hard to reach areas choose 1/2 circle | 4‐0 | Circular stapling, EEA 21, 25 mm | Circular stapler size is a limitation for small dogs and cats. Tissue thickness must be more than 1 mm and less than 2.5 mm for proper staple engagement and formation. |
| Stomach wall/Gastrotomy, Gastrectomy, Diversions; Gastric Wall Invagination | Monofilament, intermediate to prolonged absorbable suture | 1/2 circle, taper needle | 3‐0 to 4‐0 | Linear stapling GIA (green cartridge) or TA (green cartridge) |
Monocryl, Biosyn, or Maxon are recommended. Polydioxanone loses strength rapidly in acidic environments, so avoid if suture penetrates
|
