Comparison of urethral pressure profilometry and contrast radiography in the diagnosis of incompetence of the urethral sphincter mechanism in bitches

Three diagnostic indicators of urethral sphincter mechanism incompetence were compared in 25 continent and 25 incontinent anaesthetised bitches: the resting urethral pressure profile, the stressed urethral pressure profile and the radiographic position of the bladder neck. Logistic regression indicated that the best predictor of continence status was the stressed urethral pressure profile as assessed by the percentage of negative peaks extending below the resting intravesical pressure; it classified 43 of the 50 dogs correctly. The radiographic position of the bladder neck was a better predictor of continence than either the measurement of functional profile length or the maximum urethral closure pressure from the resting urethral pressure profile, whether alone or in combination. By combining the percentage of negative peaks on the stressed profile with the position of the bladder neck, 46 of the 50 dogs were classified correctly. Cut-off values for the percentage of negative peaks on the stressed urethral pressure profile, and for the radiographic position of the bladder neck are suggested for use in evaluating incontinent bitches in clinical practice.