Intestinal surgery in small animals: historical foundations,current thinking,and future horizons

Intestinal wounds require precise closure after intestinal biopsy, enterotomy, or enterectomy in small animals. Preexisting factors such as intra‐abdominal sepsis and hypoalbuminemia as well as poor surgical technique increase the risk of intestinal dehiscence, with considerable negative impact on patient morbidity and mortality. Live dog studies have demonstrated the dangers of mucosal eversion especially in the septic abdomen. Approximating patterns preserve luminal diameter, heal optimally, and have equal bursting strength compared with inverting patterns after 24 hours. Simple interrupted and simple continuous suture patterns and disposable skin staples are established alternatives for manual wound closure. Knotless quilled suture currently used in laparoscopic gastropexy techniques shows bursting strength equal to monofilament sutures in dog cadaveric intestine. Dehiscence rates with hand sewn vs titanium automated stapling anastomosis are similar in uncomplicated cases; however, auto stapling devices may be the preferred method of anastomosis when preexisting abdominal sepsis is present and when patient size allows it. Regardless of the technique, current standard of care involves leak testing and omental wrapping, followed by early postoperative feeding. The past decade has ushered in an exciting new era of laparoscopic assisted techniques that have the potential to reduce postoperative pain and patient morbidity. An understanding of these applications will establish the future of minimally invasive small animal intestinal surgery for veterinary specialists. In summary, surgeons have a variety of methods at their disposal for optimal clinical outcome in small animal intestinal surgery.     

Factors affecting incisional complication rates associated with colic surgery in horses: 78 cases (1983-1985)

From May 1, 1983 to April 1, 1985, 142 operations were performed on horses with signs of acute abdominal pain (colic), using a ventral midline incision. Seventy-eight horses lived for at least 15 days after surgery or had acute dehiscence and were included in the study. Seventy horses had surgery once, and 8 horses had surgery 2 or more times. Six-month follow-up evaluation was obtained for 66 horses that had 1 surgery and for 6 horses that had multiple surgeries. Incisional complications included drainage (including infection), acute dehiscence, hernia, and suture sinus formation. The effects of preoperative peritoneal fluid presence, enterotomy or resection, suture material and pattern used in the linea alba, type of skin closure and use of a sutured-on stent bandage on the incidence of incisional complications were investigated. The complication of incisional infection rate associated with a near-far-far-near suture pattern vs simple interrupted pattern in the linea alba was the only statistically significant (P less than 0.05) difference observed.     

In vitro bursting pressures of jejunal enterotomy closures in llamas

OBJECTIVE: To evaluate closure strength (in vitro bursting pressure) of jejunal enterotomies in llamas. STUDY DESIGN: In vitro experimental study. SAMPLE POPULATION: Jejunal specimens (n=72) from 6 llamas. METHODS: Differences in bursting pressures and luminal diameters were compared between 2 layer enterotomy closures with an initial full thickness simple continuous pattern oversewn with either a continuous Lembert or Cushing suture pattern using 3 sizes (2-0, 3-0, 4-0) of polyglactin 910 and polydioxanone. RESULTS: Bursting pressures were significantly higher for enterotomies closed with polydioxanone than polyglactin 910, independent of suture size, but there was no difference between Lembert and Cushing oversew patterns. Use of a Lembert pattern reduced intestinal diameter more than a Cushing pattern regardless of suture material or size. CONCLUSIONS: Although polydioxanone resisted higher bursting pressures than polyglactin 910, both suture materials should be considered satisfactory for jejunal enterotomy closure in llamas based on typical intraluminal pressures expected in clinical patients. The optimal oversew pattern may be continuous Cushing to maximize the luminal diameter in small intestinal enterotomy closures. CLINICAL RELEVANCE: In vitro bursting pressures may help to predict which enterotomy sites would leak post-operatively, although further studies are necessary to determine the outcome in clinical patients.     

Pullout strength for three suture patterns used for canine tracheal anastomosis

OBJECTIVE: To compare pullout strength of 3 suture patterns used for canine tracheal anastomosis. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Cadaveric canine tracheae (n = 20). METHOD: Tracheal segments were anastomosed with 1 of 3 suture patterns: simple continuous, simple interrupted, and simple interrupted reinforced with horizontal mattress, each encircling annular cartilage rings adjacent to the transection site. Horizontal mattress sutures encircled the annular rings proximal and distal to the rings closest to the anastomosis. Each construct was distracted (0.5 mm/s) in a materials testing machine to failure. Load-displacement curves were generated and failure load (pullout strength) determined and mode of failure recorded. RESULTS: Tracheal anastomosis with a simple interrupted pattern was significantly weaker (mean+/-SD pullout strength, 102.55+/-30.14 N) than simple continuous (135.53+/-15.47 N) or simple interrupted plus horizontal mattress (132.39+/-21.46 N), which were not different from each other. Mode of failure was consistently by suture tear out. CONCLUSIONS: Both simple continuous and simple interrupted reinforced with horizontal mattress suture patterns have significant biomechanical advantage over a simple interrupted pattern alone in canine cadaveric tracheal anastomosis. The simple continuous pattern had the least variability in pullout strength. CLINICAL RELEVANCE: A simple continuous technique should be considered when selecting a tension-relieving pattern for canine tracheal anastomosis. It offers the same biomechanical advantage as a simple interrupted pattern reinforced with a horizontal mattress pattern and its strength appears to be reliably maintained when tested in canine cadaver tracheae.     

Continuous absorbable suture pattern in the closure of ventral midline abdominal incisions in horses

A retrospective study was performed to evaluate the healing of ventral midline abdominal incisions, closed with a simple continuous suture pattern using absorbable suture material, in 139 horses and foals. Dehiscence and incisional hernia developed separately in two horses. The low incidence of dehiscence and incisional hernia, compared with their reported incidence following the use of interrupted suture repair, leads the authors to recommend this alternative method of abdominal incision closure in horses. The security of closure is not sacrificed and the advantages of a rapid closure are desirable.     

Esophagotomy Closure in the Dog A Comparison of a Double-Layer Appositional and Two Single-Layer Appositional Techniques

Esophagotomies were performed on 36 dogs and closed with 3-0 polydioxanone in double-layer simple interrupted, single-layer simple interrupted, or single-layer simple continuous patterns. The operative time was shortest for single-layer simple continuous closure, followed by single-layer simple interrupted and double-layer simple interrupted, respectively. Three dogs with each suture pattern were euthanatized at hours 0 and 1, and days 4 and 28 after surgery. The esophagotomy incisions were subjected to bursting strength testing and examined microscopically. The bursting wall tension was higher for all three suture pattern groups at 28 days than at 0 and 1 hour. The double-layer closure had higher bursting wall tension than the single-layer closures at 0 hour and 4 days. Single-layer simple continuous closure had the lowest bursting wall tension for each time period. Single-layer simple interrupted closure had the highest bursting wall tension at 28 days. Microscopic examination revealed close approximation of tissue planes for the double-layer closure and mucosal ever-sion for the simple interrupted and simple continuous single-layer closures. Healing was superior histologically with the double-layer closure.     

Occurrence of Incisional Complications After Closure of Equine Ventral Midline Celiotomies With 2 Polyglycolic Acid in Simple Interrupted Suture Pattern

The aim of this retrospective study was to describe the use of simple interrupted suture pattern for the closure of the abdomen after ventral midline celiotomy in horses and to evaluate the prevalence of resulting incisional complications. Seventy horses undergoing abdominal surgery (2006–2015) and surviving at least 30 days were included in the study. Closure technique of the abdominal wall was performed on three layers. Linea alba was closed with a simple interrupted pattern using number two coated braided absorbable polyglycolic acid suture. Follow-up information was recovered at the 90th day postoperatively. Incisional complications considered included drainage, infection, dehiscence, and herniation. The complications observed in the present study using simple interrupted suture pattern were 4.29% (3 of 70), lower than reported in literature with different suture pattern. Simple interrupted suture pattern could be a valid option for the closure of linea alba after ventral midline celiotomy in horses.     

Clinical comparison between a continuous Lembert pattern wrapped in a carboxymethylcellulose and hyaluronate membrane with an interrupted Lembert pattern for one-layer jejunojejunostomy in horses

Reasons for performing study: Although experimental studies have demonstrated differences in performance between methods for handsewn jejunojejunostomy in horses, information on clinical results after different methods of anastomosis are rare. Hypothesis: A continuous Lembert pattern wrapped in a carboxymethylcellulose and hyaluronate membrane would perform better than an interrupted Lembert pattern for jejunojejunostomy in horses. Methods: Data was reviewed on 32 horses that underwent jejunojejunostomy from 1993–2002. Kaplan‐Meier analyses and rates for post operative colic and death were used to compare outcomes after an interrupted Lembert pattern (15 horses with strangulating lesions and 5 horses with nonstrangulating lesions) and a continuous Lembert pattern with membrane (12 horses with strangulating diseases). Results: None of the 32 horses had post operative ileus or post operative endotoxaemia. One horse with a continuous pattern required a repeat celiotomy for anastomotic impaction. Short‐term survivals for the interrupted Lembert were 100% (nonstrangulating lesions) and 93% (strangulating lesions) and for the continuous pattern 92% (all strangulating). Long‐term rates for mortality and colic episodes were less for the continuous Lembert pattern with membrane compared with the interrupted Lembert for strangulating lesions (P<0.05) and were less for strangulating lesions than for nonstrangulating lesions (P<0.05). For strangulating lesions, Kaplan‐Meier analyses yielded a survival probability of 70% for up to 9 years after the interrupted Lembert pattern and 80% for up to 5 years for the continuous Lembert pattern. Conclusions and relevance: Both Lembert patterns performed well in clinical use, although the continuous pattern with the carboxymethylcellulose and hyaluronate membrane had superior long‐term outcomes with less colic and mortality from colic.     

Comparison of three closure methods and two absorbable suture materials for closure of jejunal enterotomy incisions in healthy dogs

The macroscopic and histological appearance of jejunal antimesenteric incisions approximated with two different absorbable suture materials (monofilament versus multifilament) and three closure techniques (appositional single layer, crushing single layer, and double layer) were compared in healthy dogs at 14 or 28 days, postoperatively. No significant differences between the two suture materials were observed for most of the macroscopic or histological variables. However, the monofilament suture material caused significantly more fibrous tissue reaction in the muscular layer of the jejunum than did the multifilament suture material. Of the three enterotomy closure techniques used in this study, the appositional single-layer method proved to be the best. The double-layer closure method caused a significant decrease in the incisional circumference, the relative circumference, and volume of the jejunum, and a significant increase in jejunal wall thickness. Our findings suggest that canine jejunal enterotomy incisions can be closed using an appositional suture pattern with relatively rapidly absorbable monofilament suture material. The use of double-layer suture patterns for closure of jejunal enterotomy incisions should be avoided because the size of the intestinal lumen may be reduced.     

Partial Maxillectomy in the Dog Comparison of Suture Materials and Closure Techniques

This study compares the healing of oronasal defects created by partial maxillectomy when closed using two different suture materials and two different suture patterns. In experiment 1, 24 dogs were divided into four equal groups. Partial maxillectomy was performed on each dog and was closed using either a two-layer simple interrupted suture pattern (12 dogs) or a modified Mayo mattress pattern (12 dogs) with either polyglactin 910 (12 dogs) or polypropylene (12 dogs) sutures. On the seventh postoperative day, the dogs were euthanized, suture line bursting pressures were measured, and wound healing was evaluated grossly and histopathologically. Suture line dehiscence occurred in one dog from each of the four groups. These were the only dogs in which electrocoagulation had been used. The healing of suture lines closed with the two-layer simple interrupted pattern was superior to that of those closed with the modified Mayo mattress pattern based on the degree of gross oral ulceration, suppurative inflammation, fibrosis and oral epithelial covering at the suture line, and the number of necrotic sites in the adjacent tissue. The healing of suture lines closed with polypropylene was superior to that of those closed with polyglactin 910 based on suture line bursting pressures and the degree of suppurative inflammation and tissue necrosis at the suture sites. In Experiment 2, partial maxillectomies were performed on four dogs, and closure was achieved using a two-layer simple interrupted suture pattern with either polyglactin 910 (two dogs) or polypropylene (two dogs). On the 30th postoperative day, the dogs were euthanized, and wound healing was evaluated grossly and histopathologically. All suture lines were well healed. All polyglactin 910 oral sutures were absent, while all polypropylene oral sutures were still present.     

Surgery: Comparison of three closure methods and two absorbable suture materials for closure of jejunal enterotomy incisions in healthy dogs

Summary

The macroscopic and histological appearance of jejunal antimesenteric incisions approximated with two different absorbable suture materials (monofilament versus multifilament) and three closure techniques (appositional single layer, crushing single layer, and double layer) were compared in healthy dogs at 14 or 28 days, postoperatively. No significant differences between the two suture materials were observed for most of the macroscopic or histological variables. However, the monofilament suture material caused significantly more fibrous tissue reaction in the muscular layer of the jejunum than did the multifilament suture material. Of the three enterotomy closure techniques used in this study, the appositional single‐layer method proved to be the best. The double‐layer closure method caused a significant decrease in the incisional circumference, the relative circumference, and volume of the jejunum, and a significant increase in jejunal wall thickness. Our findings suggest that canine jejunal enterotomy incisions can be closed using an appositional suture pattern with relatively rapidly absorbable monofilament suture material. The use of double‐layer suture patterns for closure of jejunal enterotomy incisions should be avoided because the size of the intestinal lumen may be reduced.     

A comparison of three methods of end-to-end anastomosis in the equine small colon

Six animals were used to compare simple interrupted, simple continuous, and stapled techniques for end-to-end rotated small colon anastomoses. Three ponies were evaluated three days after surgery for adhesion formation and luminal diameter at each anastomosis site. Two ponies and one horse were evaluated 14 days after surgery for adhesion formation. All anastomosis sites were examined histologically for alignment of tissue planes, and evidence of inflammation. No single technique was superior in all areas examined. While only three of the nine anastomoses had mild fibrinous adhesions at three days after surgery, all anastomoses had varying degrees of well-organized adhesions by 14 days after surgery. Three days after surgery luminal diameter was most comprised by the simple continuous technique. Although the simple interrupted technique was most consistent in its alignment of tissue planes, it was only slightly better than the simple continuous pattern. Stapled anastomoses were inverted or everted at all sites examined. Adhesion formation was less extensive, and histologic evidence of inflammation was less severe, in stapled anastomoses. The average times required to complete the simple interrupted, simple continuous, and stapled anastomoses were 22, 14, and 8 minutes, respectively.     

Life-threatening hemorrhage from enterotomies and anastomoses in 7 horses

OBJECTIVE: To report our experience with horses that presumptively had severe intraluminal hemorrhage from enterotomy or anastomosis. STUDY DESIGN: Clinical study. ANIMALS: Six adult horses and 1 adult donkey. METHODS: A retrospective study was conducted at the University of Illinois (April 1994 to December 2001) to determine the clinical course and outcome of horses with melena and/or anemia and evidence of life-threatening hemorrhage from intestinal incisions. Medical records of all horses that had colic surgery were reviewed to determine the proportion of horses with this complication. In addition, horses that fit the same criteria identified in 3 other veterinary clinics were included. RESULTS: Three horses (1.3%) of those that had enterotomy or anastomosis at the University of Illinois and 4 horses from other clinics had complications presumptively related to severe hemorrhage from these intestinal procedures. Melena became evident within 72 hours of surgery and lasted 12 to 96 hours. Six horses had an acute and severe drop in packed cell volume (PCV), increased heart rates, and other signs of acute hemorrhage, and 1 horse had signs of colic postoperatively. Horses were administered intravenous formalin (3 horses) and whole blood transfusions (4 horses). Repeat celiotomy was performed on 2 horses. In 1 of these horses, a bleeding artery was ligated in the edge of the original enterotomy, and, in the other, a 25-cm-diameter intraluminal blood clot was found occluding the pelvic flexure. A horse that had jejunocolostomy for cecal impaction was not treated for hemorrhagic shock but was euthanatized and necropsied. Necropsy revealed blood-filled bowel from the jejunocolostomy to the anus. One of the remaining 6 horses died of enterocolitis and 5 survived to discharge. CONCLUSIONS: Hemorrhage from incisional edges, particularly in the large intestine, should be considered a rare but possibly fatal complication of enterotomy or anastomosis in horses. CLINICAL RELEVANCE: To prevent fatal hemorrhage from incisional edges during enterotomy or anastomosis, large vessels should be ligated at the original surgery, and hemostatic effects of different closure techniques should be considered. No intraoperative or postoperative findings were useful to predict this complication, and response to supportive medical therapy was favorable.     

A Comparison of Simple Continuous Versus Simple Interrupted Suture Patterns for Tracheal Anastomosis After Large-Segment Tracheal Resection in Dogs

Two suture techniques for tracheal anastomosis after large-segment tracheal resection were compared. Eight cartilages were resected from the trachea of each of 12 dogs; anastomoses with 4-0 polydioxanone suture were created using a simple continuous suture technique in six dogs and a simple interrupted suture technique in six dogs. Surgical time was shorter but apposition of tracheal segments at the time of surgery was less precise with the simple continuous suture technique. The dogs were evaluated for 150 days after surgery. Clinical abnormalities after tracheal resection and anastomosis were not observed. Percent dorsoventral luminal stenosis was calculated by measuring the tracheal lumen diameter on lateral cervical radiographs. Percent luminal stenosis was calculated planimetrically using a computerized digitizing tablet. Anastomotic stenosis was mild in all dogs; however, the mean percent luminal stenosis determined planimetrically was significantly greater for dogs that had the simple continuous suture technique. Planimetric measurements of cross-sectional area made before and after formalin fixation were not significantly different. Radiographic determination of percent dorsoventral luminal stenosis was a poor predictor of diminution of cross-sectional area determined planimetrically.     

Closure of Abdominal Incisions Using A Continuous Polypropylene Suture: Clinical Experience in 550 Dogs and Cats

Closure of midline abdominal wall incisions in 469 dogs and 81 cats following various intraabdominal procedures was accomplished by using a single layer, simple continuous pattern with monofilament polypropylene. Skin was closed using simple interrupted nonabsorbable sutures. Weight of the patients ranged from 1 kg to 80 kg. Length of the incision ranged from 3 cm to 55 cm. There was one dehiscence (0.18%) and no incisional hernias. Results indicate the technique is a dependable, time saving method of abdominal closure.     

Peri-operative morbidity associated with ovariohysterectomy performed as part of a third-year veterinary surgical-training program

The present study describes the morbidity associated with ovariohysterectomy (OVH) when performed by third-year veterinary students as part of a surgical-training program. Data recorded from medical records included signalment, concurrent illness(es), surgical procedure(s), anesthesia and surgery time, anesthetic and surgical complications, and semester performed. The students' surgical training before the OVH included 39 lecture and 26 laboratory hours. In the present study, 513 animals (206 dogs and 307 cats) were included, of which 120 (23.4%) animals had concurrent illnesses. Median anesthesia time was 145 minutes (ranging from 65 to 240) for cats and 180 minutes (ranging from 90 to 360) for dogs. Median surgery time was 105 minutes (ranging from 50 to 210) for cats and 140 minutes (ranging from 65 to 265) for dogs. There were two (0.4%) major anesthetic complications, one resulting in death. There were 206 (41.7%) minor anesthetic complications, the most common being hypothermia. There were 17 (3.3%) major surgical complications, the most common being body wall dehiscence (n=15), and 49 (9.5%) minor surgical complications, the most common being seroma formation (n=35). Complications were comparable to previous reports. Specific aspects of the program identified for improvement included placing greater emphasis on securely tying the terminal knot of a simple continuous suture pattern to prevent body wall dehiscence, improved measures to reduce post-operative hypothermia, and implementing stricter health screening of animals before enrollment into the program. Faculty program coordinators are encouraged to conduct similar studies so that best practices can be shared and outcomes can be compared as we work toward determining the ideal methods of training students to instill core surgical competencies.     

Comparison of suture materials and suture patterns for inverting intestinal anastomosis of the jejunum in the horse

In 7 horses, 4 anastomoses were done in the small intestine in each, using the combinations of synthetic absorbable monofilament and multifilament suture materials with continuous- and interrupted-suture patterns in the serosubmucosal layer of a 2-layer inverting-suture technique. Horses were evaluated 30 days after the operation for adhesion formation, lumen diameter, evidence of chronic obstruction, and suture tract inflammation at the anastomosis. Postoperative obstruction occurred in 5 of the 7 horses, and 6 horses survived. One horse was euthanatized on postoperative day 6 after 48 hours of ileus and obstruction; necropsy revealed a partial intussusception involving the anastomosis done with continuous multifilament-suture material. Two other horses that became obstructed between postoperative days 3 and 5 had protracted ileus and gastric reflux up to 48 hours' duration, but survived. Horses that had obstruction after the 6th postoperative day recovered within 4 hours of onset. The continuous inverting-suture pattern in the serosubmucosal layer resulted in significantly (P less than 0.05) fewer adhesions than did the interrupted pattern, and suture material had no effect on adhesion formation. There was no significant difference in the percentage of reduction of lumen diameter between the variations of the 2-layer technique, and there was no evidence of chronic obstruction related to any of the anastomoses. Suture tract inflammation was moderate in the anastomoses, using continuous-multifilament suture, with neutrophils being the predominant cell type. The anastomoses with continuous-monofilament suture had mild inflammation with focal accumulations of neutrophils. Minimal inflammation was associated with both types of suture in the interrupted pattern.     

Comparison of incisional bursting strength of simple continuous and inverted cruciate suture patterns in the equine linea alba

OBJECTIVE: To determine the bursting strength of ventral median abdominal incisions closed by either simple continuous or inverted cruciate suture patterns. STUDY DESIGN: Experimental. ANIMAL OR SAMPLE POPULATION: Twelve equine cadavers. METHODS: A 25 cm ventral median incision was made through the linea alba and a 200 L polyurethane bladder was placed within the abdomen. Either a simple continuous or an inverted cruciate pattern using 3 polyglactin 910 with a bite size and suture interval of 1.5 cm was used to close linea incisions. Closure time was recorded for each pattern. The bladder was inflated with air at 40 L/min, and the pressure at body wall failure recorded. The length of suture used for wound closure and the wound failure modes were recorded. Deviation from the linea (cm), total suture length (cm), suture length to wound length ratio (SL:WL), closure time (min), bursting pressure (mm Hg), and failure modes were compared between groups using Welch-Aspin t-tests. The effects of independent subject variables were assessed for possible effects on bursting strength using analysis of covariance. RESULTS: Mean bursting pressure was significantly greater for the simple continuous pattern than for the inverted cruciate pattern (P = .01). Significantly less suture material (P = .0002) was required with the continuous pattern than with the inverted cruciate pattern. Mean closure time, SL:WL, deviation from the linea, and failure modes were not significantly different between groups. No significant effects were noted for independent variables in both groups on bursting strength. CONCLUSIONS: In this model, a simple continuous closure pattern for ventral median abdominal incisions was stronger than an inverted cruciate pattern. A simple continuous pattern leaves less foreign material in the wound, which may be of benefit in reducing incisional complications. CLINICAL RELEVANCE: Use of a continuous closure pattern for the linea alba may offer greater wound security during episodes of increased intra-abdominal pressure in horses.     

A comparison of 2 different suture patterns for skin closure of canine ovariohysterectomy

The purpose of this study was to compare postoperative wound healing in canine ovariohysterectomy following the use of an absorbable monofilament poliglecaprone 25 suture in 2 different skin closure techniques, the buried continuous subcuticular (BCS) suture pattern and the simple interrupted (SI) suture pattern. These 2 skin closure techniques were evaluated against a nonabsorbable polypropylene monofilament suture in an SI pattern. Wounds were assessed by using a semiquantitative scoring system at 18 to 24 hours and 10 to 14 days, postoperatively. Results indicated that the BCS closure using poliglecaprone 25 demonstrated a higher rate of tissue reactivity initially (18-24 hours postoperatively), as compared with the SI closure using either suture material. By 10 to 14 days postoperatively, poliglecaprone 25 used in a BCS closure was associated with significantly lower wound scores than was the same material used in an SI closure. It was concluded that the BCS closure may effect a better cosmetic appearance to the skin closure in a canine ovariohysterectomy at the time of the recheck appointment. Furthermore, by obviating the need for suture removal, use of the BCS pattern may eliminate the requirement for this return appointment.     

Comparison of 3 techniques for ureteroneocystostomy in cats

OBJECTIVE: To compare 3 techniques for ureteroneocystostomy in cats. STUDY DESIGN: Experimental surgical study. ANIMALS: Fifteen adult cats. METHODS: Cats (15) had ureteroneocystostomy with ureteronephrectomy of the contralateral kidney: 5 cats had an intravesical mucosal apposition technique (modified Leadbetter-Politano; intravesical-MA group), 5 cats had extravesical ureteroneocystostomy (modified Lich Gregoir) using a simple continuous suture pattern (extravesical-SC group) and 5 cats had an extravesical technique using a simple interrupted suture pattern (extravesical-SI group). Renal function was evaluated by measuring serum creatinine concentration. Ultrasonographic assessment of the kidney and ureteroneocystostomy site was performed the day after surgery, twice weekly for 3 weeks and once weekly for the remainder of the study. Cats were euthanatized 50 days after surgery. The kidney and ureter removed at surgery, the remaining kidney, ureter, ureteroneocystostomy site, and bladder were examined histologically. RESULTS: Two extravesical-SC cats were euthanatized because of azotemia and uroabdomen, and 1 died acutely at day 4 for unknown reasons. In the intravesical-MA and extravesical-SI cats, the serum creatinine concentration increased after surgery, peaking at a mean (+/-SD) of 9.4+/-2.4 mg/dL and 4.9+/-3.3 mg/dL on day 3, and decreasing to 3.4+/-5.7 mg/dL and 1.5+/-0.4 mg/dL on day 7, respectively. The extravesical-SI technique was associated with consistently lower serum creatinine concentrations for the first week after surgery compared with the other techniques. The mean serum creatinine concentration was within the reference range in cats in the intravesical-MA and extravesical-SI groups by days 10 and 5, respectively. Renal pelvic dilatation occurred in all cats but resolved more rapidly in cats after extravesical techniques. There was no significant difference in serum creatinine concentrations or renal pelvic dilation between the intravesical-MA and extravesical-SI techniques. Bladder mass height at the anastomosis site was significantly larger and persisted for longer with intravesical-MA technique. CONCLUSION: An extravesical-SI technique is seemingly the choice for ureteroneocystostomy in cats with undilated ureters. Renal pelvic dilation on ultrasound examination should be expected after ureteroneocystostomy in cats. CLINICAL RELEVANCE: An extravesical ureteroneocystostomy technique using a simple interrupted pattern for anastomosis should be considered in cats undergoing renal transplantation.