Placentitis in Mares: 2025 Vet Diagnosis, Treatment & Prevention by Dr Duncan Houston 🐴🩺

Hello! I’m Dr Duncan Houston, veterinarian and founder of AskAVet.com. In this updated 2025 guide, we explore placentitis—inflammation of the placenta in pregnant mares. This serious condition threatens pregnancy, but timely veterinary intervention can help mares to carry foals to term. We’ll cover causes, clinical signs, diagnosis, treatment, management, prognosis, and prevention strategies to support mare and foal health.

🔍 What Is Placentitis?

Placentitis is an infection or inflammation of the placenta that impairs nutrient and oxygen exchange between mare and foal. It's the leading cause of late-term abortion and early foal loss in pregnant mares.

⚠️ Causes & Risk Factors

• Ascending infections—common bacteria (e.g., _Streptococcus zooepidemicus_) enter through cervix, often following breeding, teasing, or urine pooling.
• Hematogenous spread—rare bloodborne infections cross the placenta.
• Mare overheating or heavy protozoal infection elsewhere bottom-up inflammation.
• History of placentitis increases recurrence risk.
• Reduced cervical seal or uterine tone (older mares, dystocia history).

👀 Clinical Signs in the Mare & Fetus

• Premature udder development and colostrum ("bagging up") before ~320 days.
• Vaginal discharge—brown, red, green, or purulent fluid.
• Mare may appear mildly febrile or off feed.
• Fetal distress may show as premature labor signs—mare straining or restlessness.

🩺 Diagnostic Approach

1. Transrectal palpation—detect increased uterine size, fluid pockets.
2. Transabdominal/transrectal ultrasound—evaluate combined thickness of uterus–placenta (“CTUP”) and identify fluid.
3. Milk/colostrum sampling—elevated calcium and sodium reflect early placentitis.
4. Fetal heart rate and viability check via ultrasound.
5. Cervical/vaginal culture where safe and warranted.

🛠️ Treatment Protocol (Emergency Response)

1. Antibiotics

• Trimethoprim–sulfadiazine, penicillin, or ceftiofur until term or resolution.
• Avoid potentially teratogenic drugs (e.g., tetracyclines) without vet supervision.

2. Anti-Inflammatory & Supportive Care

• NSAIDs like flunixin or phenylbutazone to reduce uterine inflammation.
• Pentosan/antilaminetics to support uterine tone and blood flow.
• Progesterone supplementation (e.g., altrenogest) to maintain uterine quiescence if indicated.

3. Uterine Support & Management

• Tail wrap and light exercise to maintain circulation, avoid stall rest unless colic risk.
• Povidone lavage of vulva between treatments to reduce ascending bacterial load.
• Repeated ultrasounds every 48–72 hrs to monitor CTUP and fetal health.

4. Induction of Parturition (When Necessary)

If fetal or maternal health is compromised, controlled induction near term (≥335 days) may reduce risk of abortion or retained placenta.

📊 Monitoring Prognosis & Outcomes

• CTUP thickness and uterine fluid trends indicate therapy success.
• Consistent fetal heart tones—>95 bpm = reassuring viability.
• Mares responding to therapy often carry to term; early treatment increases odds significantly.

📋 Prevention Strategies

1. Maintain vaginal and perineal hygiene—clean tail, treat urine pooling promptly.
2. Monitor high-risk mares (past placentitis) with monthly CTUP scans after day 300.
3. Use long-acting uterine sealants around breeding time where appropriate.
4. Vaccinate mares pre-breeding against _EHV-1_, _E. coli_, and other reproductive pathogens.
5. Provide proper nutrition and body condition to maintain uterine health.

⏳ Summary Table: 2025 Vet Placentitis Guide

🌟 Final Thoughts from Your 2025 Vet

Placentitis can jeopardize pregnancy, but with early detection and aggressive, guided veterinary treatment, many mares carry healthy foals to term. Staying vigilant, keeping hygiene high, and catching signs early are critical. 🐎✨

📲 Use the AskAVet.com app for remote monitoring, ultrasound image review, antibiotic guidance, and ongoing pregnancy support. Your mare’s pregnancy deserves expert attention—help is a click away. 💙