Gazette Vet: Spay Incontinence


by John Andersen, DVM

One of the more common problems veterinarians see that not many people are aware of is urinary incontinence in female dogs. This is also referred to as spay incontinence or hormone responsive incontinence as it tends to happen mostly in dogs who have been spayed.

First, let’s review what it means to be “spayed.” The common spay procedure is an ovariohysterectomy–surgical removal of the dog’s ovaries and uterus. There are many reasons why we recommend spaying female dogs. We spay dogs to prevent unwanted breedings and overpopulation, but also to help prevent reproductive organ disease when dogs grow older. Mammary (breast) cancer, uterine infections, and ovarian cysts are very common, if not expected, in older non-spayed female dogs. These diseases are all related to the effects of estrogen and progesterone that occur with each heat cycle. Of course, spaying female dogs also prevents their owners from having to deal with the messy discharge that occurs with each heat cycle, typically lasting for several weeks.

Interestingly, when we spay and neuter dogs, they still very much maintain male and female dog characteristics. This is because testosterone and estrogen are also produced from the adrenal glands, although in much smaller amounts than in the testes or ovaries. Now, back to incontinence…

I grew up a big fan of Wayne’s World on Saturday Night Live and they always got a big kick out of saying the word “sphincter”! But we should all be thankful for our sphincters, especially those at our bladder and rectum! When we are asleep, awake, at work, or at play, our bladder sphincter is closed tight, keeping urine from leaking out until we’re ready to go to the bathroom. It’s the same for dogs and cats. Urinary incontinence occurs when the sphincter muscle is not closed tightly enough, allowing some urine to leak out when it’s not supposed to. In spayed female dogs, this is thought to be due to a lack of estrogen hormone in the body, which helps to give that muscle more “tone.”

The classic case we see is a middle-aged to older spayed female dog who is brought in for having urinary accidents in the house. When we inquire about when the accidents occur, they always happen when the dog is sleeping, taking a nap, or resting. They may leak a small amount, or leak the entire bladder–not very fun on your couch cushions! Usually, the dogs have no idea they did it and they wake up wet and a little confused.

It doesn’t take too many of these leaking episodes for an owner to call wanting to find out what’s wrong. The first thing we recommend is to test their urine to rule out any infection or diabetes, both of which can also cause incontinence. If the urinalysis is normal, the history alone tells us it’s female urinary incontinence.

We always recommend treating urinary incontinence. Obviously, no one wants their dog leaking urine everywhere they sleep. But also, urinary incontinence puts these dogs at a high risk for developing a urinary tract infection. Often the infections that occur secondary to incontinence are not very obvious, except for worse-than-usual-smelling urine.

Fortunately, treating urinary incontinence is generally easy and successful. There are two medications available, estrogen and phenylpropanalamine (PPA).

I usually recommend estrogen supplementation because it clearly goes at the underlying cause of the problem–lack of estrogen. Estrogen supplementation is very safe and dogs who are responsive, often end up only needing one pill, once a week to maintain a tight sphincter. The challenge with estrogen supplementation is finding the right dose, as some dogs are more sensitive than others.

The other appropriate medication that is often used is PPA, often called Proin. This is actually a type of stimulant, which acts on receptors in the sphincter muscle to cause it to tighten up a little. This medication has to be given twice daily, long term, but is also generally safe and effective.

So you might ask, “Should I just not spay my dog?” Well, no. Although you will certainly decrease her risk of getting urinary incontinence, you will dramatically increase her risk of getting mammary tumors or a uterine infection. I would argue that easily more than 90 percent of non-spayed female dogs will eventually get mammary tumors or get a uterine infection that requires an emergency spay when they get older. Also you’ll have to deal with heat cycles and puppies. So risk/benefit: I’ll take the risk of incontinence, easy.

There is a group of folks out there who recommend letting dogs go through one heat cycle before spaying them, and I think this is a reasonable consideration. The “pros” are that their lower urinary tract gets some estrogen exposure that will decrease their risk of incontinence. Also, their body gets to naturally develop to maturity. The “cons” are that the prevention of mammary cancer is reduced (but still there), their owners have to deal with a messy heat cycle, and the spay surgery itself is more painful in an adult dog than a six month old puppy. Also, although the risk of urinary incontinence is reduced, it is not gone!

I recommend spaying dogs between six and nine months of age. The majority of dogs spayed at this age do NOT go on to become incontinent and the surgery is less complicated and offers a quicker recovery when they are still puppies. For some dogs that have a recessed vulva or puppy vaginitis (ask your vet), I recommend waiting for a heat cycle so these problems can resolve.

I do think that spaying at 12 to 16 weeks is too early and may be associated with a higher rate of incontinence as they get older, and there’s really no reason to do this surgery that early.

Happy New Year!