Heart Murmurs in Horses Vet Guide 2025 – Dr Duncan Houston
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Heart Murmurs in Horses Vet Guide 2025 – Dr Duncan Houston 🐴❤️
By Dr Duncan Houston, BVSc – your reliable veterinary resource for understanding, diagnosing, and managing heart murmurs in horses.
Introduction
Heart murmurs—extra swishing sounds heard between normal “lub‑dub” beats—can be benign or signal serious heart disease. In 2025, we take a deep dive into what these sounds mean, how to assess their impact, and how to manage them. With expert insight and equine-first guidance, you’ll learn to distinguish harmless murmurs from those needing intervention. 🧠
💓 What Is a Heart Murmur?
A heart murmur is the result of turbulent blood flow within the heart, often due to abnormal valve function or structural defects. Veterinarians detect them during routine exams using a stethoscope, noting timing (systolic vs. diastolic), location, intensity (graded 1–6), and radiation :contentReference[oaicite:3]{index=3}.
🧬 Physiologic vs. Pathologic Murmurs
- Physiologic murmurs are common in healthy, high-performance horses—they stem from rapid blood flow and typically cause no health issues :contentReference[oaicite:4]{index=4}.
- Pathologic murmurs indicate underlying structural problems like valve regurgitation or congenital defects, often progressing over time :contentReference[oaicite:5]{index=5}.
🏷️ Grading and Timing of Murmurs
| Grade | Description |
|---|---|
| 1–2 | Soft and often benign |
| 3–4 | Moderately loud—needs evaluation |
| 5–6 | Loud with thrill—may indicate serious disease |
Physiologic murmurs are often grade 1–2 and systolic, while louder murmurs (grades 3+) require diagnostics :contentReference[oaicite:6]{index=6}.
🩺 Common Types of Valvular Murmurs
- Aortic regurgitation (AR): Diastolic murmur—usually from valve degeneration; sometimes silent but can lead to arrhythmias :contentReference[oaicite:7]{index=7}.
- Mitral regurgitation (MR): Left-side systolic murmur; may enlarge atrium and predispose to atrial fibrillation if significant :contentReference[oaicite:8]{index=8}.
- Tricuspid regurgitation (TR): Often physiologic, especially in racehorses—but can worsen :contentReference[oaicite:9]{index=9}.
- Ventricular septal defect (VSD): Congenital defect—noted by continuous or systolic murmur :contentReference[oaicite:10]{index=10}.
🔍 Diagnosing & Monitoring Murmurs
- Thorough auscultation: Listen on both sides for at least a minute; repeated checks help detect arrhythmias :contentReference[oaicite:11]{index=11}.
- ECG: Identifies arrhythmias like atrial fibrillation, common with MR or AR :contentReference[oaicite:12]{index=12}.
- Echocardiogram: Assesses valve function, chamber size, and blood flow via Doppler ultrasound :contentReference[oaicite:13]{index=13}.
- Performance evaluation: Measuring heart recovery times, and monitoring for exercise intolerance or swelling :contentReference[oaicite:14]{index=14}.
📉 Clinical Signs & Performance Impact
- Poor performance, fatigue, slow post-exercise recovery, reduced stamina, or collapse :contentReference[oaicite:15]{index=15}.
- Jugular vein distension, rapid resting heart rate, or abnormal pulse patterns :contentReference[oaicite:16]{index=16}.
- Loud murmurs (grades ≥3), concurrent arrhythmias, or enlarged cardiac chambers warrant performance limitations :contentReference[oaicite:17]{index=17}.
✔️ Prognosis & Performance Outlook
Many horses with physiologic murmurs or mild valvular leaks perform normally with proper monitoring. Severe lesions, arrhythmias, or chamber enlargement may reduce performance or pose health risks :contentReference[oaicite:18]{index=18}.
Mitral regurgitation can worsen over time—annual ultrasounds and ECGs help track progression :contentReference[oaicite:19]{index=19}.
🛠️ Management Strategies
- Regular check-ups: Biannual veterinary exams with auscultation, ECG, and echo as indicated :contentReference[oaicite:20]{index=20}.
- Limit strenuous work: Reduce intensity if murmurs are louder or arrhythmias present.
- Medication for heart failure: Diuretics, ACE inhibitors, or inodilators may be prescribed—but not typical for isolated murmurs :contentReference[oaicite:21]{index=21}.
- Monitor fluid retention: Check body condition and edema in chest, abdomen, or limbs.
🏇 Prepurchase & Safety Considerations
Heart murmurs often reduce sale price but don't automatically disqualify a horse. A full cardiac work-up (auscultation, echo, ECG) can provide reassurance to buyers and clarify prognosis :contentReference[oaicite:22]{index=22}.
For horses with significant murmurs, sedation and anesthesia need careful planning due to increased cardiovascular risk :contentReference[oaicite:23]{index=23}.
📊 Summary Table
| Type of Murmur | Severity | Performance Risk | Management |
|---|---|---|---|
| Physiologic (grade 1–2) | Soft | No to minimal | Monitor annually |
| MR / TR (grade 3+) | Moderate | Potential reduced stamina | Echo, ECG, adjust workload |
| AR (severe) | Diastolic, loud | Significant arrhythmia risk | Echo, ECG, restrict performance |
| Congenital defects (VSD/PDA) | Variable | If large → poor prognosis | Specialist referral |
Conclusion & Ask A Vet Support 📲
Heart murmurs in horses range from harmless to health‑threatening. With expert diagnostics and monitoring, many affected horses can remain active and safe. Always seek veterinary insight—especially in athletic or breeding stock. Early detection and precise management help your horse maintain peak health and performance.
Need help interpreting murmur findings, planning diagnostics, or designing safe exercise guidelines? Ask A Vet offers custom heart health plans, reminders, and tele‑consults via our app. Download the Ask A Vet App today to keep your horse’s heart strong and your mind at ease. ❤️🐎
