As it turns out, incontinence, which is defined as involuntary urination, is quite common in dogs, especially spayed females, where approximately one in five dogs (20 percent) is affected.
Estrogen responsive incontinence or hormonally responsive incontinence, commonly called spay incontinence, is the most frequent cause of involuntary urination in dogs. It can occur anywhere from immediately after spaying to ten years later, with the average being around three years.
A recent study
showed that early spaying (before the first heat) reduced the chance of incontinence, from 18 percent to 9.7 percent in large breed dogs, but increased the severity when it occurred. It is possible that spaying midway between heat cycles may help prevent spay incontinence, but this is just speculation, as no studies have been done. Hormone-related incontinence can also affect neutered males, though much less commonly than females.
Incontinence can occur for many other reasons, including urinary tract infections, bladder stones, congenital structural defects (e.g., ectopic ureters), spinal cord disease, and excess water intake. Older dogs, overweight dogs, and dogs with neurological problems may develop a weak bladder sphincter. These causes of incontinence can affect dogs of both genders, whether intact or neutered.