Pyometra in dogs: the warning signs every owner must know
The uterine infection, in veterinary terms pyometra (“pus in the uterus”), is the most dangerous consequence of the normal cycle. It affects about one in four to five intact female dogs during her life, mostly from middle age on, and it usually comes in a specific window: two to eight weeks after a heat. If you know the window and the signs, you catch it early. Untreated it leads to blood poisoning and death.
Why it develops
After every heat progesterone stays high for about two months. It thickens the uterine lining and makes it produce glandular fluid so that embryos could implant, and at the same time it dampens the immune defence inside the uterus. This repeats with every heat and the lining changes permanently (cystic endometrial hyperplasia). At some point bacteria, usually gut bacteria such as E. coli, enter through the open cervix during the heat and find ideal conditions. The uterus fills with pus.
Hormone treatments to suppress the heat or oestrogen injections to terminate a pregnancy raise the risk considerably.
Two forms
- Open pyometra: The cervix is open and pus drains. You see yellowish, brownish or bloody-purulent, often foul-smelling discharge, and the dog licks herself a lot. This form is noticed earlier.
- Closed pyometra: The cervix is closed and the pus stays in the uterus. No discharge, but the belly grows and the dog becomes very ill faster. This form is more dangerous because the uterus can rupture.
The warning signs
Two to eight weeks after the heat watch for these signs, singly or in combination:
- Excessive drinking and urinating. Frequently an early sign, because the bacterial toxins strain the kidneys.
- Discharge from the vulva, purulent or bloody, frequently foul-smelling. May be absent in the closed form.
- Lethargy, apathy, she doesn't want to go for walks, withdraws.
- Loss of appetite, vomiting, diarrhoea.
- Fever (above 39.5 °C / 103 °F), but absent in about half of all cases; later sometimes a low temperature instead.
- Swollen, tense belly, sensitive to touch.
- Pale gums, rapid breathing, circulatory weakness: then it is high time.
Risk of confusion: the first signs look like a stomach bug or “a bad mood”. The difference is the timing. An intact female dog that is listless and drinking a lot a few weeks after her heat has pyometra until proven otherwise.
What to do
Go to the practice immediately, even at night or at the weekend. Ultrasound and a blood count confirm the diagnosis in minutes. The treatment of choice is surgery: uterus and ovaries are removed, in other words a spay under difficult conditions. Caught in time, almost all dogs survive. The longer you wait, the higher the risk from sepsis, kidney damage or a ruptured uterus.
Medical treatment is sometimes possible with the open form and in breeding bitches, but has a high relapse rate: after the next heat the pyometra often returns.
Prevention
The only reliable prevention is spaying. Removing the ovaries alone is enough: without ovaries no more progesterone is produced and the uterus can no longer become diseased. Whether that is right for your dog depends on many factors, see When to spay?. If you decide against it, keep the window after every heat consciously in view and do not use hormone preparations to suppress the heat.
How Lunella helps
After every recorded heat Lunella marks the watch window for pyometra in the calendar and reminds you four weeks after the end to check. The stage information lists the warning signs, and in the daily observation you can note drinking, discharge and general condition so that you can give precise details at the practice.
In short: pyometra usually comes two to eight weeks after the heat, occasionally later. Excessive drinking, lethargy, vomiting, discharge or a swollen belly are alarm signs. Go to the practice immediately; it is an emergency that needs surgery.
This article does not replace veterinary advice. If your dog shows signs of illness, see your vet.
