URETHRAL SPHINCTER MECHANISM INCOMPETENCE IN THE MALE DOG - IMPORTANCE OF BLADDER NECK POSITION, PROXIMAL URETHRAL LENGTH AND CASTRATION

The radiographs of 37 incontinent adult male dogs with urethral sphinc ter mechanism incompetence were compared with those of 28 control dogs to determine if, as in the bitch, differences in bladder neck positio n and urethral length were implicated in the pathophysiology of urethr al sphincter mechanism incompetence. Bladder neck position was signifi cantly different; compared with continent dogs, incontinent animals we re significantly more likely (P-less-than-0.005) to have intrapelvic t han intra-abdominal bladder necks, However, after allowing for the inf luence of body size, and unlike the situation in the bitch, there was no significant difference in proximal urethral length between the two groups. Bladder neck position was significantly related to prostate si ze (P-less-than-0.001) and it is suggested that this is one reason why castrated male dogs are more prone to urethral sphincter mechanism in competence than entire animals. A logistic regression analysis reveale d that both bladder neck position and castration status were significa nt risk factors for incontinence and that they appeared to be acting i ndependently of each other.