Treatment of Pyometra in Cats (Feline Pyometra)

1. Stabilization Before Treatment

• IV fluid resuscitation - to correct dehydration and sepsis-associated hypotension
• Broad-spectrum antibiotics - started empirically while awaiting culture results
  • E. coli is the most common pathogen, followed by Streptococcus spp., Staphylococcus aureus, and Klebsiella spp.
  • First-choice agents: amoxicillin/clavulanic acid (15-25 mg/kg orally twice daily, or IV three times daily)
  • Alternative: enrofloxacin (5 mg/kg orally or SC every 24 hours) - good uterine penetration
• Pain management - analgesics as needed
• Blood work (CBC, biochemistry) and abdominal ultrasound to assess severity

2. Surgical Treatment (Definitive and Preferred)

Ovariohysterectomy (OVH / Spay)

• The treatment of choice for pyometra in cats
• Removes the infected uterus and both ovaries - completely curative
• Indicated for: all cats not intended for breeding, open- and closed-cervix pyometra
• The uterus is more distended, fragile, and friable than in a routine spay - surgical risk is higher
• Antibiotics are continued for ~2 weeks post-operatively
• Hospitalization for 1-3 days may be needed post-surgery

• Open pyometra (cervix open, vaginal discharge visible) - usually more stable, somewhat lower risk
• Closed pyometra (cervix closed, no discharge) - higher risk due to greater uterine distension, risk of rupture, and septicemia; requires rapid stabilization and surgery

3. Medical (Non-Surgical) Treatment

Prostaglandins (PGF2α - Dinoprost/Lutalyse)

• Mechanism: Lower progesterone levels, promote cervical dilation, and stimulate uterine contractions to expel purulent contents
• Dose: 0.1-0.25 mg/kg SC once or twice daily for 3-5 days (cats require higher doses than dogs; feline corpus luteum is more refractory)
• Limitation: Frequency may need to be increased to up to 4 times daily if response is insufficient
• Serum progesterone should be checked 2-3 days after starting treatment; target is < 2 ng/mL (return to baseline)
• Side effects: Vomiting, diarrhea, salivation, restlessness, respiratory distress - these are common and transient

Aglepristone (Alizine)

• Progesterone receptor antagonist - blocks progesterone action, promotes cervical opening
• Used in some countries (Europe); not FDA-approved in the US
• Given SC at 10 mg/kg on days 1, 2, and 8
• Can be combined with prostaglandins for better efficacy
• Better tolerated than prostaglandins

Cabergoline (dopamine agonist)

• Causes luteolysis by reducing prolactin
• Sometimes used in combination protocols

Transcervical uterine lavage

• Described in large non-domestic felines
• Not practical in domestic cats due to the small vaginal canal

Monitoring during medical treatment

• Daily physical examination
• Daily or every-other-day abdominal ultrasonography to confirm uterine evacuation
• Reassessment of CBC and serum biochemistry
• If the cat does not respond or deteriorates - proceed to surgery immediately

4. Post-Treatment Follow-up

5. Key Points Summary