Many dog owners are unaware of the signs and symptoms of pyometra, a life-threatening infection in female dogs. If not treated, it can lead to death.
Pyometra is an infection that affects females dogs during or after their heat cycle. Pyometra can be very dangerous, because it causes pus buildup in the uterus and around other organs (such as the ovaries). It can also cause fever and vomiting if left untreated.
What is Pyometra?
Pyometra is Latin for ‘pus-womb’. You may also hear it called a ‘pyo’. It refers to an infection of the uterus (womb) and is a very serious condition affecting female dogs (bitches).
Which dogs does pyometra affect?
The condition affects unneutered (entire) bitches. Age is a risk factor, meaning that older bitches are at increased risk.
Much less commonly, a pyometra can occur in spayed females, if a small piece of tissue was left behind at the time of neutering. This is called a stump pyometra.
A study published in 20011 demonstrated breed differences in the risk of developing a pyometra. Those identified as being at higher risk included Rottweilers, Cavalier King Charles Spaniels, Golden Retrievers, Bernese Mountain Dogs, and English Cocker Spaniels whereas German Shepherd Dogs, and Dachshunds appeared to be at low risk.
How common is pyometra?
Research shows around 1 in 4 entire bitches are affected by the time they reach 10 years old.1
How and why does a pyometra occur?
Hormonal changes that occur during the bitch’s season leave the reproductive tract prone to infection. Bacteria track up the reproductive tract, where they cause the uterus to fill with pus.
Repeated seasons cause changes in the uterus (thickening and inflammation) which increase the chance of infection. This explains why age is a risk factor for a pyometra developing.
What are the signs a bitch has a pyometra?
A pyometra typically develops 1-2 months after a bitch has her season. Signs include:
- Increased thirst
- Discharge from the vulva* (this can be smelly)
- Licking the vulva
- Tiredness, lethargy
- Increased urination
- Reduced appetite
- Vomiting and diarrhoea
*A study published in 20142 showed that 23% of affected bitches did NOT have vaginal discharge, showing the importance of getting them checked out even in the absence of this ‘classic’ symptom.
What are ‘open’ and ‘closed’ pyometras?
When people refer to open versus closed pyometras, they are talking about the condition of the cervix (the opening to the womb). An open pyometra is when the cervix is open meaning you are more likely to see a discharge from the bitch’s vulva. In a closed pyometra, the cervix is firmly shut, meaning you do not see a vaginal discharge. Closed pyometras can be particularly dangerous since they are harder to spot and are at risk of bursting.
What happens if a pyometra bursts?
If a pyometra bursts, its infected contents are released into the abdomen. This causes a lot of inflammation (called peritonitis) and often, sepsis.
How is pyometra diagnosed?
The combination of the dog’s symptoms as well as the timing of her last season will often be enough to make the vet suspect a pyometra. They will perform a full clinical examination (including a vaginal examination). An abdominal (belly) ultrasound will be necessary to confirm their diagnosis and they may also suggest a blood test.
How is pyometra treated?
The safest and most effective treatment is surgical removal of the uterus and ovaries (an ovariohysterectomy or spay procedure). Intravenous fluids, pain relief and antibiotics will likely also be required.
Surgery seems like a big deal for an infection – can’t the vet just use antibiotics?
The infection is tightly enclosed inside the uterus, making it hard for antibiotics to penetrate the tissues and take effect. In some instances (when the cervix is still open, referred to as an ‘open pyometra’) the vet might suggest trying antibiotics and hormone injections together. However, medical treatment is often not successful and recurrence at the next season is common.
Can pyometra be prevented?
Pyometra can be prevented by surgical neutering (spaying). It is one of the reasons neutering is recommended in any bitch from which owners do not intend to breed.
I think my bitch may have a pyometra, what should I do?
A pyometra is a very serious condition and if left untreated, can be life-threatening. It is a veterinary emergency and any bitch showing symptoms must receive immediate veterinary attention.
Should I be worried?
The mortality rate for pyometra is 3-4%1,2. Complications can occur (peritonitis, sepsis, urinary tract infections) but most bitches make a full recovery. The most important factor in ensuring survival is that the gets prompt veterinary treatment.
- Jitpean S, Ström-Holst B, Emanuelson U, Höglund OV, Pettersson A, Alneryd-Bull C, Hagman R. Outcome of pyometra in female dogs and predictors of peritonitis and prolonged postoperative hospitalization in surgically treated cases. BMC Vet Res. 2014 Jan 7;10:6. doi: 10.1186/1746-6148-10-6.
- Egenvall A, Hagman R, Bonnett BN, Hedhammar A, Olson P, Lagerstedt AS. Breed risk of pyometra in insured dogs in Sweden. J Vet Intern Med. 2001;15(6):530–538. doi: 10.1111/j.1939-1676.2001.tb01587.x.
Author: Dr Victoria Strong BSc (Hons) BVSc DVetMed AFHEA MRCVS