“Heart Murmurs in Horses: A Quick Guide For What Owners Should Know – Help Us Spread The Word” – Email 25

Hello , 

Your horse’s heart is extraordinary. Working tirelessly to power movement, health and performance. But when a vet mentions a heart murmur, it can feel worrying, confusing, and full of unanswered questions. That’s why our recent IH Masterclass with Professor Gunther van Loon, one of the world’s leading equine cardiologists from Ghent University, was such a gift.

Professor van Loon very rarely teaches directly to horse owners – usually his work is shared within veterinary and academic circles – so having his time, knowledge and kindness in explaining complex subjects was genuinely special. He guided us through what murmurs and irregular rhythms really mean, how they are properly assessed in clinical practice, and how vets weigh up performance, welfare and safety.

It was packed with clarity, reassurance, and solid science… and if you haven’t watched the recording yet, you absolutely should. 

In the meantime, here’s a quick, accessible guide to help you make sense of the key points from the webinar –  what murmurs are, what they don’t automatically mean, and how to approach them calmly and sensibly for your horse’s sake.

But truly… do watch the full recording when you can. This was a special one….

– Abi & The IH Team

Heart Murmurs in Horses: A Quick Guide For What Owners Should Know

1. What is a murmur, in plain English?

• A heart murmur is simply an extra or unusual sound that a vet hears when listening to the heart with a stethoscope.
  • A normal heartbeat is a clear “lub–dub, lub–dub” (two main sounds per beat).
  • A murmur is a whoosh / hiss / musical noise heard around those two sounds, caused by turbulent blood flow inside the heart or the big vessels leaving it.
• Common causes of that turbulence include:
  • A slightly leaky valve (blood going backwards when it shouldn’t)
  • A narrowed area or small hole the blood is being forced through
  • Less commonly, changes in the blood itself (e.g. very thin/anaemic blood)
• Key points for you as an owner:
  • A murmur is a description of a sound, not a diagnosis.
  • Some murmurs are harmless “incidental” findings and horses still work and compete normally.
  • Others indicate a more serious problem and need ultrasound (echo) and sometimes ECG to know:

2. Murmurs that are often low concern

(Provided a vet has checked properly)

• Soft, quiet murmurs (especially in young or fit horses) where:
  • The horse has normal performance
  • Heart size on ultrasound is normal
  • No arrhythmias (abnormal rhythms) on ECG, including during exercise
• Certain small congenital defects (like small ventricular septal defects) can be:
  • Well compensated
  • Compatible with normal work or even competition, if echo/ECG parameters are good and monitored.

Note: If the heart is structurally normal, the chambers aren’t enlarged, and rhythm is good – many murmurs are more of a “note and monitor” than a crisis.

3. Murmurs that deserve closer attention

These don’t automatically mean disaster, but they must be assessed…

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