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Nell's Story, Pyometra in Dogs

Nell had a smelly, blood-tinged discharge from her vulvar area and an uncomfortable firm abdomen

I remember old “Nell” well, a lovely, elderly, retired working Collie. On her examination she had a very smelly, blood-tinged discharge from her vulvar area and an uncomfortable firm abdomen. Her Temperature was up, and she looked miserable. She had been off food, drinking a lot, and she had been sick a couple of times. Nell had all the symptoms of having Pyometra, and an advised ultrasound scan and blood tests confirmed this. 

Pyometra is a secondary infection that occurs as a result of hormonal changes in the female's reproductive tract. 

Each time a female dog has a heat or “season”, usually about twice a year every six months, she undergoes all the hormonal changes associated with a pregnancy, regardless of whether she becomes pregnant or not. The resultant changes in the uterus that occur during each season make pyometra more likely with her advancing age and with each season. Following each oestrus, the hormone progesterone remains elevated for up to two months and causes the lining of the uterus to thicken in preparation for pregnancy. If pregnancy does not occur for several consecutive oestrus cycles, the uterine lining continues to increase in thickness. Cysts can also form within the thickened uterine tissues, a condition called cystic endometrial hyperplasia. This thickened, cystic lining secretes fluids that can create an ideal environment for bacterial growth. In addition, the muscles of the uterus cannot contract properly, either due to thickening of the uterine wall or the high levels of the hormone progesterone. This means that bacteria that enters the uterus and fluids that have accumulated cannot be expelled. The combination of these factors can often lead to the life-threatening infection, pyometra. 

Symptoms of pyometra usually develop around four to six weeks after the female dog has finished bleeding from her last oestrus cycle.  In some cases, she may appear to be having an abnormally prolonged heavy season. If left untreated these signs will worsen to the point of dehydration, collapse, and sadly sometimes in severe cases, death from septic shock.  

The clinical signs depend on whether or not the cervix remains open or closed. If it is open, pus will drain from the uterus through the vagina to the outside. A pus or an abnormal discharge is often seen on the skin or hair under the tail, and she may be licking herself excessively, and off food and lethargic. If the cervix is closed, pus that forms is not able to drain to the outside. Instead, it collects within the uterus ultimately causing the abdomen to distend. The bacteria release toxins that are then absorbed into the bloodstream. Dogs with closed pyometra become severely ill very rapidly. They are off food, very listless and very depressed. Vomiting or diarrhoea may also be present. Toxins released by the infection affect the kidney's ability to retain fluid. Increased urine production occurs, and many dogs drink an excess of water to compensate. Increased water consumption may occur in both open- and closed-cervix pyometra. 

Your vet will probably suspect your dog has pyometra based on your description of the presenting signs, from their examination of your pet and on questioning their recent history. They may advise investigative procedures such as imaging: X-rays and ultrasound, and blood tests, to confirm the diagnosis, to rule out other possible causes, and to check that your pet is well enough to undergo any advised surgical treatment. 

The treatment of choice for pyometra is surgery to remove the ovaries and uterus. The operation is essentially the same as a routine spay, a full ovariohysterectomy. However, there is more risk involved and a higher chance of complications when the operation is being carried out on an already sick pet with an enlarged, vascular, infected womb. Your dog will be given intravenous fluids, antibiotics, and pain relief as support. 

Pyometra is a serious and life-threatening infection which only occurs in non-spayed female dogs. If your dog has pyometra, she will need emergency surgery which is far riskier, longer, and more complicated than a routine spay. Recovery will also be slower, and your dog may need to be for hospitalised for monitoring.  

The only way to avoid any risk of pyometra, is to get your dog spayed. This surgery can be done before her first season from 6 months of age, or 2 to 3 months after a season. Spaying your female dog at a young age will help prevent this serious condition occurring in the first place. Spaying is an important, advised procedure which prevents unwanted pregnancies, decreases the risk of mammary cancer, and completely eliminates the risk of pyometra. Also, a routine spay and general anaesthetic on a healthy patient is much safer than an emergency surgery on a critically ill patient. 

Thankfully, old Nell made a good recovery from her emergency surgery, and she was soon happy “supervising” the younger dogs around the farm again! 

If you are concerned or need advice on spay surgery for your female dog. Please do contact your Vet for good professional advice. 

Alison Laurie-Chalmers,
Senior Consultant,
Crown Vets

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