Intact, unspayed female dogs are at risk for having an unwanted pregnancy as well as developing breast cancer and developing an infection in the uterus. This infection is called a pyometra (“pyo” meaning pus and “metra” meaning uterus).
Pyometra is often the result of hormonal changes in the reproductive tract. Following estrus (“heat”) in the dog, progesterone levels remain elevated for eight to ten weeks and thicken the lining of the uterus in preparation for pregnancy. If pregnancy does not occur for several estrus cycles, the lining continues to increase in thickness until cysts form within it. The thickened, cystic lining secretes fluids that create an ideal environment in which bacteria can grow. Additionally, high progesterone levels inhibit the ability of the muscles in the wall of the uterus to contract. It is generally seen in older female dogs, but potentially could occur at any age.
This is what happened in the case of Sammy, an 8 year old black Labrador Retriever. Sammy was brought in one day because of some discharge from her vulva that she was licking. The owner thought she might have a urinary tract infection, but the discharge was thick, rather than clear like urine. Since Sammy hadn’t been spayed, my first concern was a pyometra.
There are two possibilities with a pyometra. If the cervix is open, then the pus in the uterus will drain out the vulva. These dogs don’t usually feel too sick and the diagnosis can be more difficult. The other possibility is that the cervix is closed. When this occurs, pus and bacteria continue to accumulate and distend the uterus–like having a large abscess inside the abdomen. Dogs with a closed pyometra are usually very sick–drinking a lot, very lethargic, vomiting, and running a high fever.
Sammy didn’t have a fever and apart from licking a lot at her back end, she was acting pretty normal. Sometimes x-rays are taken to look for an enlarged uterus or bloodwork done to look for changes that would indicate an infection. Since I suspected an open pyometra with Sammy, I didn’t think x-rays would be of much use. But bloodwork was done and found that she had a very high white blood cell count.
There is no good medical treatment for a pyometra, particularly in a non-breeding dog. Surgery is the very best option as it removes the source of the infection and prevents it from reoccurring. If a dog has a closed cervix, surgery needs to be done ASAP as there is always the risk of the uterus rupturing and spreading infection into the rest of the abdomen. Since Sammy’s uterus was draining and she felt fine, she was started on antibiotics and scheduled for surgery the next morning.
This is a picture of Sammy on her back after being anesthetized. You can see her swollen vulva and the brownish discharge at the bottom. The fur on her abdomen has already been shaved in preparation for surgery.
A large area of the abdomen is shaved to allow enough room to make a large incision. The uterus can be quite diseased and tear , so it is important to be able to get into the abdominal cavity easily.
This is the uterus before removal. It is a Y-shaped organ with two horns (to better hold lots of puppies!). It is a little thicker than normal because of the infection inside. But the tissue looks healthy and there is no sign of any leakage into the body cavity.
All the blood vessels were tied off and the ovaries and uterus removed together. Then the body wall and the skin were sutured back together.
There are many reasons to get your dog (or cat) spayed early–no unwanted pregnancies, decreased risk of breast cancer, but no risk of pyometra is certainly a very important one!