Pyometra in Dogs: A Dangerous Condition Every UK Owner Should Know
Pyometra is a life-threatening infection of the uterus that primarily affects unspayed female dogs, usually occurring in the weeks following a season. It can develop very rapidly and, if untreated, leads to septicaemia and death. Every owner of an unspayed female dog should be able to recognise the warning signs.
Key takeaways
- Pyometra typically develops four to eight weeks after a season — increased thirst, lethargy or vaginal discharge in an unspayed female are warning signs requiring urgent veterinary assessment.
- Emergency spay surgery costs £800–£2,000 and is the most reliable treatment — medical treatment is far less effective.
- Routine spaying completely prevents pyometra and is the most effective way to protect unspayed female dogs from this life-threatening condition.
What Is Pyometra?
Pyometra literally means 'pus in the uterus'. After each oestrus (season), the hormone progesterone prepares the uterine lining for potential pregnancy, causing glandular development and reduced immune defences in the uterus. With repeated cycles, the glands can become cystic (cystic endometrial hyperplasia), providing ideal conditions for bacterial growth. Bacteria — most commonly E. coli — ascend from the vagina and cause a severe uterine infection.
Pyometra typically occurs four to eight weeks after a season in middle-aged or older dogs, though it can affect females of any age. It can also develop after misguided treatment with progesterone-based hormonal drugs intended to delay seasons. An open pyometra — where the cervix remains open and pus drains vaginally — is more obvious; a closed pyometra — where the cervix is sealed and pus accumulates — is more dangerous because the infection builds up with no outlet. Closed pyometra carries a higher risk of uterine rupture and sepsis.
Symptoms to Watch For
In an open pyometra, the most obvious sign is a discharge from the vulva — purulent (pus-like), often malodorous, in the weeks following a season. The dog may excessively lick the area. Systemic signs include increased thirst and urination (toxins from the infection interfere with the kidneys' ability to concentrate urine), lethargy, reduced appetite, vomiting and abdominal discomfort.
In a closed pyometra, there is no external discharge, making it harder to spot. The dog appears increasingly unwell: lethargic, anorexic, vomiting and developing a distended, painful abdomen as the infected uterus enlarges. Without treatment, the dog goes into septic shock — very high temperature followed by hypothermia, pale gums, rapid weak pulse — and dies. Any unspayed female dog that has recently been in season and is showing illness, increased thirst or lethargy must be seen by a vet urgently.
Diagnosis
Your vet will take a history and perform an examination. Blood tests — specifically white cell count, biochemistry and C-reactive protein — will show significant infection and potentially kidney or liver involvement. Abdominal X-rays or ultrasound are used to visualise the enlarged, pus-filled uterus and confirm the diagnosis; ultrasound (£150–£300) is particularly sensitive.
In a dog with an obvious history (recent season, vaginal discharge, increased thirst) the diagnosis is often clear from history and examination alone. Blood tests add approximately £80–£150. In sick dogs, urgent stabilisation with IV fluids and antibiotics is initiated before or alongside the diagnostic workup. The goal is to get the dog stable enough for surgery as quickly as possible.
Treatment and Costs
Emergency surgical spay (ovariohysterectomy) — removal of the ovaries, uterus and the infected contents — is the definitive and by far the most reliable treatment. This involves general anaesthesia in a compromised patient, which carries elevated risk compared to routine spaying. Emergency surgical spay typically costs £800–£2,000 depending on the complexity, how ill the dog is and what supportive care is needed pre- and post-operatively. Hospitalisation of one to three days for IV fluids and antibiotics adds to this.
Medical treatment using prostaglandins and antibiotics exists but is less reliable, carries significant risks, is only suitable for open pyometra, and is generally reserved for valuable breeding dogs where preserving fertility is essential. For the vast majority of dogs, surgery is the right choice. After successful treatment and recovery, prognosis is generally excellent. The most effective prevention is spaying — routine spaying before the first or second season eliminates the risk of pyometra entirely.
Find a Vet Near You
Pyometra is an emergency that can arise suddenly. Use CompareMyVet at app.comparemyvet.uk to find your nearest vet practices and see their published prices, so you know exactly where to go if your dog becomes ill after a season.
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Common questions
A closed pyometra can deteriorate to life-threatening septic shock within 24–48 hours. An open pyometra progresses more slowly but can still cause serious systemic illness. In both cases, the sooner the dog is treated surgically, the better the prognosis.
Yes — the recurrence rate after medical treatment is high, with some studies reporting that more than 50 per cent of dogs treated medically develop pyometra again in a subsequent cycle. Surgical spay after successful medical treatment is often subsequently recommended.
Spaying before the first or second season eliminates pyometra risk. The optimal age for spaying is a nuanced discussion that depends on breed and size — large breeds may benefit from delaying spaying to allow full physical development. Discuss the pros and cons with your vet.
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