Urinary Incontinence Caused by a Weak Bladder. Let’s talk more specifically about the details involving weak bladder sphincter incontinence. The medical term is urethral sphincter mechanism incompetence (USMI). This condition is the most common cause of urinary incontinence in spayed female dogs.
https://www.petmd.com/dog/general-health/incontinence-senior-dogs-what-do-and-how-help