Canine Pyometra

We’ve had a pretty crazy week at the hospital. Though I’d rather not have so many pets be sick, it’s always rewarding to have helped so many of them. Friday afternoon brought in a somewhat common emergency surgery that I’d like to talk about for this week’s post.


Pyo = pus
metra = uterus

Pyometra is a condition that results in a severe infection inside the uterus of a non-spayed female animal. Each time a female animal is in heat, the hormones produced by the ovary prepare the lining of the uterus for fertilized eggs to implant and begin growing into puppies. In a normal dog, if a pregnancy does not occur, the uterus will shed that lining and return to a quiet state until the next heat cycle. When the uterus is repeatedly stimulated by these hormones without a pregnancy occurring, the lining can stay thickened and secrete quite a bit of fluid. Bacteria make their way into the uterus from the outside world. They encounter a perfect setting inside the uterus to grow out of control. This infection leads to the buildup of pus inside the uterus. Pus is essentially an accumulation of white blood cells that have moved out of the bloodstream to fight an infection.

Pyometra cases come in two types: open and closed. This refers to the condition of the cervix. When the cervix is closed, the pus doesn’t flow out of the genital tract. This makes it harder for owners to notice (and for us to diagnose). When the cervix is open, the pus can flow out of the genital tract, which leads to a very visible (and gross) discharge from the vulva.

The signs we see that make us think about a pyo as a diagnosis are:
•Older unspayed female dog (over 5 years, but it can happen at any age)
•Heat cycle within the last 1-2 months
•Increased drinking and urinating
•Pus discharge from the vulva (sometimes)

We can also use xrays, ultrasound, and bloodwork to help us diagnose a pyometra.

When a dog has a pyo, she’s generally pretty sick. Owners usually notice this and make an appointment promptly. When a dog doesn’t get a relatively early exam, she can be very sick. Two serious consequences can result. The bacteria or their toxic products can eventually get into the bloodstream. This creates a condition called sepsis or septicemia. It can be rapidly fatal. The other consequence can happen in a closed pyo. The uterus can rupture, spilling the pus and bacteria into the abdominal cavity. This, too, can be rapidly fatal.

The general rule for handling a pyo is “never let the sun set on a pyometra.” Pyometra is an emergency that needs to be dealt with immediately. You don’t wait until the following day to put the treatment in motion.

Surgery is the main, best way to take care of the problem. We simply spay the dog, with the same procedure as we would for a younger, healthy animal. An incision is made in the abdominal wall. We tie off the blood vessels connected to the ovaries, then cut the ovaries free. They stay connected to the uterus, however. We then clamp and tie off the uterus close to the vagina. The majority of the uterus is then cut out of the abdomen. We remove ovaries and uterus all in one piece. The abdomen is flushed out with lots of warmed IV fluid, then sewn up. The skin is stitched neatly together and we recover the patient from anesthesia.

The only risks with this surgery over a regular spay are rupture of the uterus, or complications from the dog being septic.

Most patients feel tons and tons better right after surgery. Some need a day or so to recover fully. We send them home on pain medication and an antibiotic. Stitches come out 10-14 days later. There generally aren’t any long term complications from a pyo, thankfully.

Our patient from Friday is doing quite well. 🙂

Below is a diagram of a normal dog uterus.

Female genital organs Hills Color Atlas

If you’re interested in seeing what a pyo-affected uterus looks like, click the “2” below. It’s a surgical photo, just to give you a fair warning.


1 Comment

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One response to “Canine Pyometra

  1. Chris Miner

    Yet another reason to spay as soon as the dog is old enough. Why risk an infection that can turn deadly so fast?

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