🩺 Equine Coital Exanthema (ECE): A Vet’s 2025 Guide | Dr Duncan Houston BVSc

Meta description: Comprehensive 2025 veterinary guidance from Dr Duncan Houston on equine coital exanthema—lesions, diagnostics, treatment, prevention & Ask A Vet assistance.

1. 🧬 What Is ECE?

Equine coital exanthema is a benign but contagious venereal disease in horses caused by **equid alphaherpesvirus‑3 (EHV‑3)**. It manifests as papules, vesicles, pustules, and superficial ulcers on the external genitalia of breeding horses :contentReference[oaicite:3]{index=3}.

2. 🌍 Occurrence & Significance

Reported globally since the early 1900s—first seen in Ireland and now endemic in breeding populations worldwide :contentReference[oaicite:4]{index=4}. Though non‑systemic and non‑abortive, it disrupts breeding schedules and may carry economic costs :contentReference[oaicite:5]{index=5}.

3. ⏱️ Incubation & Spread

Clinical signs appear 4–8 days post exposure via breeding, contaminated instruments, rectal exams, or shared gloves :contentReference[oaicite:6]{index=6}. Virus transmits only during the active lesion phase; latency follows with uncertain reactivation risk :contentReference[oaicite:7]{index=7}.

4. 🩺 Clinical Signs

• Genital lesions: Vesicles/pustules on vulva, clitoris, or penis/prepuce that ulcerate into painful sores (1–2 mm) :contentReference[oaicite:8]{index=8}.
• Secondary infection: Bacterial colonization may lead to mucopurulent discharge, fever, and swelling :contentReference[oaicite:9]{index=9}.
• Behavioural signs: Mares may show discomfort during breeding; stallions may refuse mating due to pain :contentReference[oaicite:10]{index=10}.
• Other areas: Occasionally lesions on lips, teats, or nostrils :contentReference[oaicite:11]{index=11}.

5. 🔬 Diagnosis

Begin with clinical signs; confirm using:

• PCR assay: Highly sensitive and specific :contentReference[oaicite:12]{index=12}.
• Electron microscopy: Identifies typical herpesvirus particles :contentReference[oaicite:13]{index=13}.
• Virus culture: Traditional but less widely used due to lab limitations.
• Serology (CF or neutralization): Useful adjunct but not reliable alone; may cross-react with EHV‑1/4 :contentReference[oaicite:14]{index=14}.

6. 🏥 Treatment & Management

• Sexual rest: Cease breeding until all lesions fully heal (~2–3 weeks) :contentReference[oaicite:15]{index=15}.
• Isolation: Keep affected horses separate to prevent spread :contentReference[oaicite:16]{index=16}.
• Topical care: Clean with saline or mild disinfectant; apply antibiotics if bacterial infection occurs. No antiviral therapy is standard; a 2017 study used valacyclovir in Japan with some benefit :contentReference[oaicite:17]{index=17}.
• Supportive care: Pain relief (e.g., NSAIDs), monitor appetite, and ensure lesion hygiene to prevent discomfort and complications.

7. 🛡️ Prevention & Biosecurity

• Hygiene: Use single-use gloves and disinfect instruments between animals; prevent cross-contamination :contentReference[oaicite:18]{index=18}.
• Screening: Examine breeding stock before covering; delay mating if any lesions noted.
• Isolation during outbreaks: Restrict breeding and equipment sharing for 2–3 weeks post-recovery.
• Donor semen safety: Use fresh or frozen semen only from EHV‑3‑negative or recovered stallions.
• No vaccine: Currently none available :contentReference[oaicite:19]{index=19}.

8. 📈 Prognosis & Industry Impact

Lesions typically heal fully with residual scars, and fertility is unaffected by EHV‑3 :contentReference[oaicite:20]{index=20}. Short-term breeding delays cause economic losses, especially in stallions used in AI programs :contentReference[oaicite:21]{index=21}.

9. 💬 Ask A Vet Support

• 📋 Develop breeding-shed biosecurity protocols tailored to your operation.
• 📸 Remote lesion review and healing monitoring via photos.
• 📆 Alerts for quarantine clearance, wound check, and PCR confirmation.
• 🎓 Webinars: “Venereal Herpes in the Breeding Shed,” “Instrument Disinfection Best Practice,” “AI program safeguards.”

10. ❓ FAQs

Can EHV‑3 cause long-term fertility issues?

No—fertility returns post-healing, with no effect on reproduction :contentReference[oaicite:22]{index=22}.

Can stallions hide symptoms?

Yes—stallions may carry lesions internally or have mild signs. Always inspect sheath and prepuce :contentReference[oaicite:23]{index=23}.

Is recurrence possible?

Re-infection can occur in future seasons, as immunity is short-lived; strict biosecurity is key :contentReference[oaicite:24]{index=24}.

Can non-breeding horses be infected?

Yes—via contaminated equipment during exams or palpation :contentReference[oaicite:25]{index=25}.

11. ✅ Final Takeaway

Equine coital exanthema is a benign yet contagious venereal herpes infection. Prompt recognition, breeding rest, hygiene, and isolation effectively control the disease. While fertility isn't harmed, breeding schedules can be affected. Ask A Vet is here to help you implement biosecurity and clearance protocols—ensuring your breeding program stays healthy, compliant, and productive in 2025 and beyond.