Pyometra in intact female guinea pigs is a closed or open infection of the uterus that frequently develops alongside or after ovarian cysts. The classic signs are a swollen lower abdomen, bloody discharge from the vulva, decreased appetite, and lethargy. Mortality is high if untreated, but ovariohysterectomy at an exotic surgery center clears the infection and prevents recurrence (Hawkins & Bishop, 2012, Vet Clinics NA Exotic). Sows over 3 years with prior cystic ovarian disease are the highest-risk population.
Last reviewed: June 2026
What Pyometra Is
Pyometra is bacterial infection of the uterus accompanied by accumulation of pus within the uterine horns. In guinea pigs it usually occurs in middle-aged to older intact sows, often layered on top of cystic ovarian disease that has caused chronic endometrial stimulation. Closed pyometra (cervix closed, pus trapped inside) is the most dangerous form because the sow becomes systemically toxic without obvious external discharge. Open pyometra shows bloody or pus-tinged discharge from the vulva and is easier to recognize.
Signs Owners First Notice
Owners typically notice a progressively swollen lower abdomen, blood-tinged or purulent vulvar discharge, reduced appetite, weight loss despite eating, lethargy, and a hunched posture. Late-stage cases show severe weakness, fever, and rapid breathing. Hair loss on the flanks from concurrent ovarian cyst-driven hyperestrogenism is a frequent associated finding. The 2010 AEMV exotic mammal guidance highlights that vague non-specific signs in older sows should prompt urgent ultrasound rather than wait-and-watch (AEMV Pet Care Guides, 2024).
Causes and Risk Factors
Older intact sows (over 2 to 3 years) are at highest risk, particularly those with documented ovarian cysts. Chronic estrogen exposure from cysts thickens the endometrium and creates a hospitable environment for ascending bacterial infection — usually from coliforms, Streptococcus, or Staphylococcus species. Previous reproductive history, age, and overall body condition all influence risk. As described in Quesenberry and Carpenter's Ferrets, Rabbits, and Rodents, elective spay between 6 months and 2 years dramatically reduces lifetime pyometra risk.
How It's Diagnosed
Abdominal ultrasound is the most reliable test, showing a fluid-filled, dilated uterus with thickened walls. Radiographs reveal a tubular soft-tissue mass dorsal to the bladder. CBC typically shows leukocytosis with a left shift. Vaginal cytology of any discharge shows degenerate neutrophils and bacteria. The 5-Minute Veterinary Consult emphasizes that closed pyometra can be missed without ultrasound because there may be no external discharge to suggest the diagnosis.
Treatment
Ovariohysterectomy is the definitive treatment. Pre-surgical stabilization with IV fluids, antibiotics (enrofloxacin or trimethoprim-sulfa), and pain management is essential. Anesthesia in a systemically ill guinea pig carries higher risk and should be performed by exotic-experienced veterinary surgical teams. Medical management with prostaglandins is rarely successful in guinea pigs and is not recommended as primary therapy. Post-operative recovery requires close monitoring of appetite, hydration, and analgesia for 7 to 10 days.
When to See a Vet
Call your vet today if:
- Bloody or pus-tinged discharge from the vulva
- Progressively distended abdomen in an intact older sow
- Reduced appetite or weight loss for more than 48 hours
- Hair loss on the flanks combined with abdominal swelling
- A previously well sow becomes lethargic and hunched
Go to the ER immediately if:
- A guinea pig stops eating and drinking for more than 12 hours
- Severe lethargy with closed eyes, hunched posture, and weakness
- Pale gums, cold ears, and rapid breathing
- Sudden collapse or inability to walk
- Rigid, painful abdomen
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Frequently Asked Questions
Is pyometra always fatal without surgery?
Open pyometra has a slightly better prognosis with aggressive antibiotic and fluid therapy, but most sows that survive medical management alone relapse within weeks to months. Closed pyometra without surgery is essentially uniformly fatal as the sow becomes septic. Spay is the definitive treatment.
How much does diagnosis and treatment cost?
Initial exotic vet exam typically runs $75 to $200 in the US. Ultrasound costs $200 to $500. Pre-surgical bloodwork is $100 to $250. Emergency ovariohysterectomy at an exotic surgery practice runs $1,200 to $3,500 depending on severity and stabilization needs. Post-operative hospitalization and pain control add $300 to $800. Elective spay before pyometra develops is dramatically cheaper at $400 to $900.
Can pyometra be prevented?
Elective spay between 6 months and 2 years prevents pyometra and significantly reduces the risk of mammary tumors and ovarian cysts. For older intact sows kept as breeders, monthly home palpation and annual ultrasound screening catches early changes before infection develops.
What's the prognosis after surgery?
Sows who survive surgery generally have a good prognosis and live a normal lifespan. Early stable cases have surgical mortality below 5 percent in experienced hands. Septic, debilitated sows have meaningfully higher anesthetic risk, which is why catching the condition early matters.
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