Web Chapter 71 Bladder position and the exposure of the vesicourethral junction and proximal urethra to intraabdominal pressure also are important in preserving continence. When sudden increases in abdominal pressure occur, an increase in pressure occurs within the bladder and in the proximal and midurethra, termed pressure transmission (Gregory and Holt, 1994). Several studies have evaluated the relationship of urethral position and length, as well as the vesicourethral angle to incontinence (Gregory, 1994; Gregory, Cripps, and Holt, 1996). However, these measurements overlap in normal and affected dogs; many incontinent dogs have short urethras and intrapelvic bladders. Despite lack of definitive evidence for a direct cause-and-effect relationship, bladder and urethral position appear to be an important risk factor for incontinence. The relationship of hormone status to incontinence has long been recognized. As many as 20% of neutered female dogs are expected to develop some degree of urinary incontinence during their lives, and 75% of these dogs will do so within 3 years of neutering. Decreased estrogen concentrations in women are associated with loss of urethral muscle tone, urethral vascular atrophy, and decreased glandular secretions, affecting major components of the continence mechanism. Decreased estrogen concentrations are likely a factor in the development of incontinence in dogs, but the lack of clinically recognized incontinence in anestrus-intact females (and the many ovariectomized dogs without incontinence) supports a more complex mechanism than a simple lack of trophic effect (Richter and Ling, 1985). Recent evidence suggests that increases in luteinizing hormone and follicle-stimulating hormone associated with estrogen decrease also may play a role in the development of incontinence in dogs, but the mechanism has yet to be determined (Reichler et al, 2005).
Urinary Incontinence
Treatment with Injectable Bulking Agents
Cause