Evaluation of complications and long-term outcomes in dogs with surgically treated urethral prolapse

Abstract

Objective

The objective of this study was to evaluate the complications and long-term postoperative outcomes in dogs diagnosed with urethral prolapse (UP) that underwent urethropexy and/or urethral resection and anastomosis (uRA).

Animals and procedure

Medical records of 21 client-owned dogs undergoing urethropexy and/or uRA were reviewed. Complications and long-term outcomes were assessed retrospectively.

Results

Twenty-one dogs were included, and all dogs survived to discharge. The overall complication rate was 52.3%, with recurrence the most common complication (n = 8/11). Six of 8 dogs with recurrence underwent revision surgery, with 1 dog that underwent 5 revision surgeries involving a salvage partial penile amputation due to persistent recurrence. English bulldog was the most prevalent breed (47.6%) and was significantly associated with UP. There were no significant associations between the procedure (single versus combined), number of sutures placed for urethropexy, suture material, or suture pattern for uRA, and the risk of complications. Castration did not influence the risk of complications.

Conclusion and clinical relevance

Urethropexy and uRA were safe when done as single or combined procedures. Recurrence was the most prevalent complication in this study, and may warrant multiple revision surgeries. Appropriate communication about the risk of recurrence and the potential for multiple revision surgeries is recommended for owners with dogs undergoing UP repair.

INTRODUCTION

Urethral prolapse (UP) refers to protrusion of the urethral mucosa beyond the tip of the penis. Dog breeds such as English bulldogs and Yorkshire terriers are reported to be genetically predisposed to this condition (1). It is thought to be associated with brachycephalic obstructive airway syndrome, tracheal collapse, and prostatic and urinary tract disease, due to increased intraabdominal pressure generated from the increased effort of breathing or dysuria (1). More commonly, it is reported in intact male dogs due to the exhibition of excessive sexual behavior (2). Dogs with UP present with hematuria, bleeding from the penis, or a red or purple tissue protruding from the tip of the penis (3,4). Treatment for UP in dogs includes urethral mucosal reduction with purse-string suture, urethropexy, or urethral resection and anastomosis (uRA) (5). Castration is typically recommended in intact male dogs to decrease sexual tendencies; however, neuter status has not been proven to affect rates of recurrence or outcome following surgery (1). Urethral prolapse recurrence rates remain high even with surgical intervention, at 66% and 56% for urethropexy and uRA, respectively (1). A recent study by Healy et al compared the complications and recurrence rates of 79 dogs that underwent urethropexy, uRA, or a combination of both, and reported a higher risk of recurrence with urethropexy than with uRA (38.6% and 11.1%, respectively) (6). To date, there is still limited information on this condition, with most relevant literature in the form of case reports or case series.

The aim of this study was to evaluate the complication rates, long-term postoperative outcomes, and associated risk factors of dogs that underwent urethropexy, uRA, or both combined. Our first hypothesis was that the overall complication rate would be high. In addition, we hypothesized that a combined approach would lead to a lower recurrence rate.

MATERIALS AND METHODS

Medical records from dogs that underwent urethropexy and/or uRA at the Ontario Veterinary College Companion Animal Hospital (Guelph, Ontario) and the Toronto Animal Health Partners Emergency and Specialty Hospital (Toronto, Ontario) between January 1, 2013 and June 1, 2023 were reviewed and included. To meet inclusion criteria, dogs must have had a documented physical examination and undergone urethropexy and/or uRA done by a Board-certified surgeon or a resident under supervision. Dogs were excluded from the study if they did not meet these criteria or if the follow-up duration after surgery was < 100 d.

Data collected before surgery included information on signalment (age, sex, neuter status, weight, breed), clinical signs, bloodwork, appearance of prolapsed tissue, approach used (combined or independent), duration of anesthesia and surgery, and any complications occurring at a minimum of 100 d following surgery. Intra- and postoperative complications were classified using the Classification of Intraoperative Complications (CLASSIC) criteria and the Accordion Grading System, respectively (7).

Follow-up information was obtained at a minimum of 100 d after surgery via phone call with the owner or updated medical records from the referring veterinarian. Clinical signs present for < 30 d were classified as acute, whereas those exhibited for > than 30 d were considered chronic. Postoperative long-term outcomes (poor, fair, or good) were determined by the presence of any recurring clinical signs that contributed to the overall quality of life of the dog. A “poor” outcome was assessed if the dog had persistent clinical signs that necessitated surgical revision, a “fair” outcome if the dog had intermittent recurring clinical signs that could be managed medically, and a “good” outcome if no recurrent clinical signs were noted.

Statistical analysis

For relationships in which the outcome variable was numeric, we used a one-way ANOVA and a Kruskal-Wallis test to test for a significant relationship. The Kruskal-Wallis test was included to check the same conclusion in cases for which the assumption of normality was not reasonable.

For relationships in which the outcome variable was a binary categorical variable, we used the X² test and the Fisher exact test to test for a significant relationship. The Fisher exact test was included if there were < 5 observations in a cell of the contingency table, in which case the X² test was not ideal.

Finally, for relationships in which the outcome variable was a categorical variable with > 2 levels, we use multinomial regression to model the relationship. A likelihood ratio test was then used to compare this model to the null model (one in which there was just an intercept) to test for a significant relationship.

All analyses were done in the R software environment using Positron. A P-value < 0.05 was considered statistically significant.

RESULTS

Study population

A total of 21 dogs examined between January 1, 2013 and June 1, 2023 met the inclusion criteria. The median age was 11 mo (range: 5 mo 10 y). There were 14 sexually intact males and 7 castrated males. Eight of 21 dogs (38.1%) underwent urethropexy, 1 dog (4.7%) underwent uRA, and 12/21 dogs (57.2%) underwent a combination of both procedures concurrently. In the urethropexy group, 2/8 dogs were neutered and 6/8 dogs were intact males. The only dog in the uRA group was sexually intact. In the combined group, 5/12 dogs were neutered and 7 were sexually intact.

The most common dog breed was English bulldog (n = 10/21), followed by American bulldog (n = 4/21), mixed breed (n = 2/32), and Staffordshire bull terrier, dachshund, boxer, toy poodle, and miniature golden doodle (n = 1/21 each). The overall mean weight was 23.8 kg (median: 24 kg, range: 7.7 to 47.7 kg). The English bulldog breed was significantly associated with UP (P = 0.00039).

History and preoperative clinical signs

The most common clinical signs were bleeding from the penis (n = 14/21), observed prolapsed tissue at the penis (n = 10/21), hematuria (n = 3/21), excessive licking of the penis (n = 3/21), stranguria (n = 2/21), and pollakiuria (n = 2/21). The durations of clinical signs were recorded in 19/21 dogs and the median duration was 4 d (range: 1 to 210 d). Most dogs (n = 18/21) were classified as having acute clinical signs, whereas 3/21 dogs had chronic signs. Two out of 21 dogs had a previous history of UP (with surgical correction at a separate institution) and were presented with a recurrent issue. In the urethropexy group, 6/8 dogs exhibited acute clinical signs and 1 dog had chronic clinical signs. The only dog in the uRA group had acute signs. In the combined group, 9 dogs exhibited acute clinical signs and 2/12 dogs had chronic clinical signs. The durations of clinical signs were not recorded in 2 dogs — 1 in the urethropexy group and 1 in the combined group. There was no significant association between the duration of clinical signs and the surgical procedure (P = 1.00).

Preoperative laboratory findings

Twenty of 21 dogs had undergone preoperative complete blood (cell) count and serum biochemistry analyses. Anemia was documented in 2/20 dogs and leukocytosis in 5/20 dogs (median: 17 × 10⁹/L, range: 15 to 21 × 10⁹/L). Urinalysis was done in 11/21 dogs, and 3 dogs (n = 3/11) had evidence of bacteriuria.

Intraoperative surgical findings

The prolapsed urethra was observed to be hyperemic but patent in all 21 dogs. Necrosis of the prolapsed tissue was reported in 4/21 dogs. Three dogs (n = 3/4) with reported necrosis underwent a combined procedure, whereas 1 dog underwent uRA only.

Of the 8/21 dogs undergoing urethropexies, 3 urethropexy sutures were placed in 6/8 dogs, and 4 urethropexy sutures were placed in the remaining 2/8 dogs. Seven of 8 dogs had sutures made of polydioxanone. Poliglecaprone 25 was used in 1 dog. Most dogs (n = 5/8) received 3-0 sutures and the remaining 3 dogs received 2-0 sutures.

Among the 12 dogs that underwent a combination of urethropexy and uRA, 6/12 dogs had 2 urethropexy sutures placed, 3 dogs had 3 placed, and 1 dog each had 1 and 5 placed. The number of sutures was not documented in 1 dog that underwent the combined procedure. Polydioxanone sutures were placed in 8 dogs (n = 8/12), whereas poliglecaprone 25 was used in 2 dogs. The type of suture material was not documented in 2 dogs in the combined procedure group. Similarly, 3-0 suture was the most common size (n = 6/12), followed by 2-0 (n = 2/12), 4-0 (n = 2/12), and 5-0 (n = 1/12). Suture size was not documented in 1 dog in the combined group.

A simple interrupted suture pattern was used for the uRA in 9 dogs (n = 9/12) in the combined group. A simple continuous suture pattern was used in 2/12 dogs in the combined group. The suture pattern was not documented in 1 dog in the combined group. Poliglecaprone 25 was used for the uRA in 7 dogs, and polydioxanone was used in 4 dogs. The type of suture material was not documented in 1 dog in the combined group. Seven of 12 dogs from the combined group received 4-0 sutures and 4/12 dogs received 5-0 sutures. Suture size was not documented in the remaining dog.

In the only dog that underwent uRA alone, a simple interrupted suture pattern was made using 4-0 polydioxanone.

Owners of all 14 intact male dogs were offered castration for their dogs undergoing urethropexy and/or uRA; however, only 13/14 dogs underwent castration and the remaining dog did not undergo the procedure (at the owner’s request). Aside from castration, 10/21 dogs underwent concurrent procedures during the same anesthetic period, including bilateral laryngeal sacculectomy (n = 6/10), staphylectomy (n = 5/10), bilateral alarplasty (n = 4/10), bilateral tonsillectomy (n = 3/10), laparoscopic-assisted cystotomy (n = 1/10), and cherry eye correction (n = 1/10).

Surgical and hospitalization durations

The surgical duration of UP repair was documented in 11/21 dogs. The mean duration of UP repair was 38.6 min (median: 30 min, range: 15 to 90 min). There was no significant difference in surgical duration depending on the type of procedure done (P = 0.37). The mean duration of hospitalization was 1.29 d (median: 1 d, range: 0 to 4 d).

Postoperative complications

No dog had documented intraoperative surgical complications. All dogs survived to discharge. There were 11/21 dogs (52.3%) with reported complications. In terms of post-operative complications, these were classified as mild in 1/21 dogs, and were classified as severe in 10/21 dogs (7). There were no postoperative complications reported in 10 dogs. The dog that experienced mild complications underwent a combined uRA and urethropexy. Intermittent hemorrhage from the surgical site was reported after surgery and resolved ~1 mo postoperatively without intervention. Among the 10 dogs that had major complications reported, 4 dogs underwent urethropexy, 1 dog underwent uRA, and 5 dogs underwent both procedures concurrently. The most common severe complication was recurrence, reported in 8/10 dogs. Of the remaining 2/10 dogs with severe complications, 1 dog exhibited stranguria. One urethropexy suture was removed, with resolution of clinical signs. The other dog exhibited progressive stranguria and dysuria. A urethral stricture was diagnosed at a recheck 3 mo after surgery, via a contrast retrograde urethrocystogram. This dog underwent revision surgery involving a penile tip amputation. Subsequent follow-up at 106 d post-revision surgery revealed resolution of clinical signs and normal urination habits.

Eight dogs had recurrence of the UP. Recurrence was reported at a mean of 206 d from surgery (median: 60 d, range: 4 to 390 d), with 4/8 dogs experiencing > 1 recurrence. Six dogs (75%) underwent revision surgery. The remaining 2/8 dogs with recurrence did not undergo revision surgery (at the owner’s request) and were lost to follow-up, respectively. Three of 6 dogs that received revision surgery developed subsequent recurrence. One of these dogs underwent 5 additional revision surgeries before a penile amputation and scrotal urethrostomy was elected as a salvage procedure. Another dog developed recurrence 2 mo after revision surgery. At that time, it was manually addressed, with no further recurrence. The remaining dog developed recurrence 3 mo after revision surgery due to a suture breakdown, and further revision was declined by the owner.

There were no significant associations of occurrence with the English bulldog breed (P = 0.27), surgical procedure used (P = 1.00), age (P = 0.15), weight (P = 0.33), and the risk of complications.

There was no significant association between the number of urethropexy sutures placed and the risk of complications (P = 0.58). There was no significant association between the suture size and complication rates for urethropexy (P = 0.24) or uRA (P = 0.64), respectively. There was no significant association between the suture pattern for uRA and the complication rate (P = 0.17).

Among the dogs that were castrated at the time of UP repair, castration was not significantly associated with the risk of recurrence (P = 0.86). Overall, the duration of hospitalization was not significantly associated with the complication rate (P = 0.62).

Postoperative long-term outcomes

The mean follow-up duration was 759 d (median: 603 d, range: 100 to 1847 d). Overall, long-term outcomes were classified as good in 15/21 dogs, fair in 1/21 dogs, and poor in 5/32 dogs. One dog was categorized as having a fair outcome due to intermittent inappropriate urination episodes at home > 427 d after surgery. Among the 5 dogs with outcomes reported as poor, 4 dogs developed recurrences. Of those, 2 underwent further revision surgeries with subsequent recurrences, 1 of which required a penile amputation (~730 d after initial surgery) and scrotal urethrostomy. The owners of the remaining 2 dogs with reported recurrences declined revision surgery. The last dog with an outcome determined as poor was reported to have difficulties urinating due to a narrowed urethral opening from scarring without evidence of a UP.

DISCUSSION

Urethral prolapse repair involving urethropexy and/or uRA is safe in dogs. All dogs in this study survived for at least 100 d following surgery. More than half of the dogs in our study population experienced severe postoperative complications, with recurrence being the most common complication. Therefore, our first hypothesis was not rejected. In our study, 50% of dogs with reported recurrence that underwent revision surgery developed subsequent recurrence. This high recurrence rate was similar to those in the published literature, in which recurrence rates were reported to range between 26 and 57% (1,6). In contrast, in a recent study published by Mas et al, only 2/20 dogs over a median long-term follow-up period of 694 d developed recurrence, of which only 1 dog required revision surgery (8). In a large retrospective study published by Healy et al, a low median number of surgical interventions required for resolution of UP (1.26) was reported over a median follow-up duration of 423 d (6,8).

The difference in results could be due to the overall short minimum follow-up durations ranging between 11 and 19 d in the latter studies, potentially missing some dogs experiencing complications. Despite our small population size, all dogs in our study had a minimum follow-up period of 100 d and an overall median follow-up duration of 759 d. Our findings may therefore be more representative of the long-term outcomes of dogs surgically treated for UP, compared to other studies. The findings in our study suggest that the risk of recurrence (even with subsequent revisions), alongside other complications, may be high and should be discussed in detail with owners before pursuing surgical repair.

In our study, the procedure used (single versus combined, urethropexy versus uRA) did not influence the complication rate; therefore, our second hypothesis was rejected. There is currently variable evidence regarding the relationship between the surgical procedure used and the success of UP repair. In the study from Healy et al, recurrence was reported to be higher with urethropexy alone compared to uRA (6). On the other hand, Grewal et al reported a significantly lower recurrence rate with a combined procedure (urethropexy and uRA) compared to uRA alone (9). These differences were hypothesized to be due to variability in surgeon experience and assessment, breed differences within the study population, and perioperative management strategies (9). The lack of significant results in our study could have reflected a type II error related to having a single case in the uRA group. Prospective evaluation of the relationship between the type of procedure and the long-term outcome should be employed for better characterization.

Despite excessive sexual drive and presence of a urinary tract infection being suspected causes of UP, castration in conjunction with UP repair was not significantly associated with decreased or increased rates of complications (1–2,9). This was in agreement with previous literature, in which castration status did not affect prolapse development or outcome (1). In this study, castration was strongly recommended in conjunction with UP repair to reduce the risk of recurrence; therefore, only 1 intact male dog was not castrated (at the owner’s request). This may have led to selection bias in our results and the clinical relevance of these findings is still unclear.

In our study, English bulldog was the most prevalent breed, consistent with previous reports, and a breed-associated correlation was identified. A significant difference in age at presentation for UP between brachycephalic dogs and other dog breeds was previously reported, suggesting that there may be a genetic predisposition of English bulldogs to UP (8–11). Additional research is required in a larger population to evaluate the relationship between breed and incidence of UP.

Aside from the potential selection bias and type II error discussed, other limitations of this study included the variability of data collated from a private and an academic institution and differences in surgeon experience.

In conclusion, urethropexy and uRA were safe when done as single or combined procedures. Recurrence was the most prevalent long-term complication in this study, and may warrant multiple revision surgeries. Applying a single versus a combined technique did not affect the risk of complications in this population of dogs. This decision may be based on surgeon preference. Castration in conjunction with UP repair requires further investigation with a larger population of affected dogs, to determine if there is any effect on the prolapse recurrence rate when these procedures are combined. The English bulldog breed was overrepresented in dogs with UP in our study. CVJ