This study compared the effects of urinary diversion by tube cystostomy catheterization, urethral catheterization and tube cystostomy and urethral catheterization on healing urethral anastomoses in the canine urethra. Fifteen intact, mature males were divided into three groups of five dogs. Urodynamic studies were performed under halothane anesthesia preoperatively and at ten weeks postoperatively. Urethral anastomosis was performed in all dogs over a urethral catheter with 4-0 polyglyconate. Group U dogs (n=5) received transurethral catheters. Group C dogs (n=5) received tube cystostomy catheters, and Group B dogs (n=5 ) had both a transurethral catheter and a cystostomy tube placed. All dogs had catheters maintained with a closed urine collection system for seven days. Dogs were observed for ten weeks following surgery, and urinalysis and urine cultures were performed on weeks 1, 4, and 8. Preoperative evaluations were repeated ten weeks postoperatively just prior to termination of the study. Radiographic and histopathologic evaluation of the urethral specimen was performed. No significant differences among the groups were noted after the second postoperative week when comparing observation scores for urination and posturing. Measurements made on in-vivo and in-vitro urethrographic studies revealed less luminal reduction at the anastomotic site in Group C when compared to Groups B and U. Results of this study indicated that urinary diversion by tube cystostomy will minimize the percent luminal diameter reduction (PLDR) when compared to transurethral catheterization alone and tube cystostomy combined with transurethral catheterization. The author recommends tube cystostomy be considered for urinary diversion following primary closure of urethral defects due to the ease of maintenance and increased patient tolerance of the technique. / Master of Science