CLINICAL, URODYNAMIC, AND HISTOLOGIC EFFECTS OF URETHRAL INTUSSUSCEPTION IN CLINICALLY NORMAL DOGS

Objective-To evaluate clinical and histologic effects of surgically cr eated urethral intussusception and determine whether it creates a high -pressure zone that resists passive urine flow in clinically normal do gs. Animals-8 healthy adult sexually intact female dogs. Procedure-Ure thral pressure profilometry was used to measure maximal urethral closu re 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 anesth etized dogs immediately before and after surgery. Dogs were assigned t o 4 groups of 2 dogs each; groups were euthanatized 4, 14, 28, and 90 days later, and representative tissues were examined. Results-Dog 1 de veloped complete postoperative urethral obstruction. The procedure was altered, and ail dogs recovered without complication. Mild inflammati on attributable to surgical manipulation, but not ischemic damage or r eduction of the intussusception, was evident. Comparison of preoperati ve MUCP and FPL with postoperative values did not yield significant di fferences. Immediate postoperative CLPP and CLPV were significantly hi gher 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 d ogs. Conclusions-Urethral intussusception does not have deleterious ef fects 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 clini cally normal dogs.