EFFECT OF INTRAABDOMINALLY INDUCED PRESSURE ON THE URETHRAL PRESSURE PROFILES OF HEALTHY AND INCONTINENT BITCHES

Objective-To determine whether reduced pressure transmission is of imp ortance in the pathophysiologic mechanism of urinary incontinence in b itches. Animals-20 sexually intact, continent bitches and 21 spayed, i ncontinent bitches. Procedure-Urethral pressure profiles before (resti ng) and after (stressed) insufflation of gas in the abdominal cavity w ere recorded in bitches under general anesthesia. Differences (stresse d minus resting) were calculated for all variables. On the basis of th ese values, the pressure transmission ratio was determined. Results-Re sting pressure profiles of incontinent bitches indicated significantly (P < 0.05) lower maximal closure pressure (4.5 +/- 3.0 cm of H2O) tha n did those of continent bitches (11.2 +/- 7.2 cm of H2O). The intra-a bdominal pressure increase lead to a shortening of total profile lengt h, which was equal in both groups and caused an increase in maximal ur ethral pressure. The change in maximal urethral pressure was significa ntly (P < 0.05) greater in incontinent bitches (12.4 +/- 4.1 cm of H2O ) than in continent bitches (8.8 +/- 4.5 cm of H2O). The profile areas and the pressure transmission ratios did not differ significantly (P < 0.05) between the 2 groups. Conclusion-The effect of decreased press ure transmission on the urethra is not a factor in the pathophysiologi c mechanism of urinary incontinence attributable to urethral incompete nce in bitches.