Clinical, urodynamic, and histologic effects of urethral intussusception in clinically normal dogs

Objective-To evaluate clinical and histologic effects of surgically created urethral intussusception and determine whether it creates a high-pressure zone that resists passive urine flow in clinically normal dogs. Animals-8 healthy adult sexually intact female dogs. Procedure-Urethral pressure profilometry was used to measure maximal urethral closure pressure (MUCP) and functional profile length (FPL) in dogs sedated with xylazine hydrochloride and atropine before and 2, 4, 7, 14, 28, 60, and 90 days after surgery, Cystourethral leak point pressure (CLPP) and cystourethral leak point volume (CLPV) were determined in anesthetized dogs immediately before and after surgery. Dogs were assigned to 4 groups of 2 dogs each; groups were euthanatized 4, 14, 28, and 90 days later, and representative tissues were examined. Results-Dog 1 developed complete postoperative urethral obstruction. The procedure was altered, and ail dogs recovered without complication. Mild inflammation attributable to surgical manipulation, but not ischemic damage or reduction of the intussusception, was evident. Comparison of preoperative MUCP and FPL with postoperative values did not yield significant differences. Immediate postoperative CLPP and CLPV were significantly higher than preoperative values, but were not significantly increased at euthanasia. A distinct but nonsignificant pressure spike was observed in postoperative urethral pressure profiles and persisted in 7 of 8 dogs. Conclusions-Urethral intussusception does not have deleterious effects when performed as described. Urodynamic data do not support the premise that urethral intussusception will create a high-pressure zone in the urethra that will resist passive urine flow long term in clinically normal dogs.