In my last blog, I mentioned the pros and cons of spaying and neutering. One of the reasons  I quoted for spaying (sterilizing) a bitch was that of eliminating the risk of pyometra. I will attempt to explain the topic in simple terms. I will try to refrain from using complicated terms as much as possible.  

What is pyometra?

Pyometra is a condition where the uterus gets infected and filled with pus. It is a medical emergency and if left untreated, or if it is not picked up in time, it will ultimately end up killing your bitch. 

… But how does it come about?

The mechanism on how it occurs is not entirely understood. Studies have shown that it has to do with bacteria and hormones. Unlike humans, the uterus of the bitch goes through the same exact process, where hormones are concerned, whether the bitch becomes pregnant or not.

The bitch has an increase in the secretion of estrogen when she first comes in season. Once the bitch ovulates, her progesterone, another hormone, goes up whether she gets pregnant or not. Progesterone is necessary to maintain a viable pregnancy. It stays up for 2 months, whether she gets pregnant or not, and goes down at the time when the pregnancy would have ended. This signs the body to give birth if the bitch is carrying puppies. The rise in estrogen and progesterone thicken the lining of the uterus. When the bitch gives birth, this lining is shed and the whole process starts again once the bitch has another heat (estrus).

When the bitch doesn’t become pregnant, the progesterone goes down at the end of the two months. Since the bitch does not go into labor, the lining of the uterus is not shed. This causes the lining of the uterus to become thicker with every season she is not bred.  “Pockets” may develop between the layers allowing the perfect hosting environment for bacteria. This leads us to the next question….

How does the bacteria end up in the uterus?

When the bitch is having her season, the cervix is open so that it allows sperm to enter the uterus, allowing the bitch to become pregnant. An open cervix allows bacteria, which is normally present in the vagina to ascend through it and into the uterus.  Studies on the DNA of the bacteria found in the uterus have shown that it is the same bacteria present lower down in the vagina, and not bacteria coming from the environment.

What are the symptoms?

Pyometra typically develops somewhere between 2 to 8 weeks after a bitch has had her season. The symptoms are very unspecific and can easily go unnoticed in some bitches. Some bitches may appear tired, depressed and have a lack of appetite. Some bitches spike a fever or develop vomiting and/or diarrhea. Others may drink more and subsequently urinate more or they may present with a distended (swollen) and/or painful abdomen. Some bitches may have none of these symptoms and simply appear slightly “off”. Others have a discharge/pus coming out of their vulva, possibly mistaken by novice owners as another season. It is not unheard of for pyometra to go undiagnosed or misdiagnosed until it is too late. It is therefore up to you to remind your vet that your bitch is intact (not spayed) and let him/her know when her last season was. 

How is Pyometra diagnosed?

The vet will likely examine the bitch. Upon feeling her abdomen s/he might feel an enlarged uterus, the bitch may tense up or even appear in pain. Please do not fiddle around with your bitch’s abdomen yourself, especially if you do not know what you are feeling for. Pressing the uterus too hard may cause it to rupture leaking the contents into the abdomen. This effectively signs a death sentence for your bitch. 

After examining the bitch, the vet will likely take a set of bloods to establish what is going on. A vet may be able to see some changes on xray, however, the gold standard for diagnosis is an ultrasound. 

And once diagnosed? What are my options?

There are two types of pyometra, open and closed. In open pyometra, the cervix is open. Most of the time, contents are leaking out of it and the bitch, more often than not, will present with a discharge. Closed pyometra happens when the cervix remains closed, allowing for a build up of pus inside the uterus with no possibility of leaking out, unless the uterus ruptures and the contents leak into the abdomen, a situation we need to prevent at all costs.

In the case of closed pyometra, most vets will opt for spaying as soon as possible. Every second is vital. Every minute left untreated is an extra minute in which the uterus can rupture and kill the bitch. One also needs to note that a spay under an emergency situation, where other organs might also possibly be failing is a much riskier procedure than a normal spay. In a normal spay, most variables are controlled, the bitch is healthy and certified by the vet fit to withstand the operation. In an emergency situation, the cards change. The surgery is being done to attempt to save her life, and hence the bitch might still be operated upon even if she is unstable, simply because if not operated on, she will most definitely die. 

In the case of open pyometra, there may be other options available if caught early enough. Prostaglandins (hormone like substances) may be given to the bitch to encourage the uterus to contract and expel the pus. These are very often prescribed alongside antibiotics. It is important to note that not every bitch with open pyometra can be treated with prostaglandins. If pyometra is caught at a later stage, inducing the uterus to contract may cause it to rupture and subsequently kill the bitch. It is therefore at the discretion of your vet which method to use based on the findings of the tests carried out. 

Treating pyometra with prostaglandins usually happens under a set of particular criteria. Most owners and vets will opt for an emergency spay unless a bitch is very valuable to a breeding programme. Some articles state that it won’t be easy for the bitch to conceive after pyometra due to scarring in the uterus. Several breeders who have experienced it and canine reproduction specialists will tell you otherwise. Several breeders have had litters from bitches after they suffered from pyometra. The recommendation by most reproduction specialists is however, to breed the bitch the following season and watch the bitch carefully. Failing to do so might result in another episode pyometra.  

Special considerations

Research has shown that estrogen injections increase the likelihood of the bitch developing pyometra. Estrogen injections, also known as mismate injections, are usually given to a bitch to abort a litter in the eventuality she is accidentally bred. Oops litters unfortunately happen if we are not careful. If it happens, evaluate carefully the pros and cons of giving a mismate injection also factoring in the possibility of the bitch developing pyometra. 

The other special consideration is stump pyometra. Stump pyometra is fairly uncommon but common enough to deserve a mention. In stump pyometra, an infection occurs in the stump left behind where the uterus was cut off . This may happen in an ovary sparing spay or when ovarian tissue is inadvertently left inside. In both these cases, the hormones which regulate a bitch’s season are still present, hence still predisposing the bitch to pyometra. Unfortunately stump pyometra has an increased likelihood of going undiagnosed because pyometra is the last thing to come to mind in the case of a spayed bitch! 


By now you have probably realised that I am not the biggest fan of spaying and neutering, especially when done at a very young age. Having said that, I feel that prevention of pyometra is a very legitimate reason for spaying a bitch. Pyometra normally affects middle-aged to older bitches however truth be told, it is not unheard of to occur in  younger bitches, even as young as those having a first season. As with most things in dogs, there is no one size fits all. Do your own research, discuss with a vet you trust and possibly your breeder and decide what the best course of action for your bitch would be.