Urethral sphincter mechanism incompetence: update on the disease and its treatment

Urethral sphincter mechanism incompetence (USMI) is the most common cause of urinary incontinence in adult female dogs. A prevalence of 5.12% in a population of 566 ovariohysterectomized (OVH) dogs have recently been reported¹. USMI typically affects middle-aged large breed spayed bitches. Larger dogs have an increased risk of developing USMI^1,2. Clinical signs such as urine leakage during sleep or periods of excitement may develop a few weeks to several years after spaying, most commonly after 2 to 3 years. A recent study2 confirmed a median time between neutering and development of incontinence of 3.73 years.

The influence of age at neutering is still debatable. Forsee et al.1 found no significant difference in the age at time of OVH between continent and incontinent dogs in a population of 566 OVH dogs, while Beauvais et al. found only weak evidence that neutering before the age of 3 months, could increase the risk of incontinence³. A more recent study on 163 neutered female dogs observed a decrease in the hazard of USMI for every month delay of neuter in the first year in dogs weighing more than 25 kg². [...]