Heart murmurs in horses (also referred to as equine heart murmurs) are a common finding during routine veterinary checkups. While some murmurs are harmless, others may indicate underlying heart disease. This article provides an in-depth breakdown of heart murmurs in horses, covering their causes, classification, diagnostic methods, and impact on a horse’s health and performance.
What Is a Heart Murmur in Horses?
A heart murmur is an abnormal heart sound caused by turbulent blood flow within the heart or blood vessels. It is detected using a stethoscope during auscultation. While some murmurs are considered “innocent” and do not affect a horse’s well-being, others may be associated with underlying cardiac disease.
Causes of Heart Murmurs in Horses
Heart murmurs in horses can be caused by physiological (benign) conditions or pathological (disease-related) conditions.
1. Physiological (Innocent) Murmurs
These murmurs occur in healthy horses and do not indicate disease. They are often related to the high cardiac output and large heart size of horses.
- Common in young, athletic horses
- No impact on performance or longevity
- Disappear over time or remain stable
2. Pathological (Disease-Related) Murmurs
Pathological murmurs are caused by heart valve disease, structural abnormalities, or blood flow disorders. Some common conditions include:
a. Valvular Regurgitation (Leaky Valves)
Valvular disease occurs when a heart valve does not close properly, allowing blood to leak backward. The most affected valves in horses include:
- Mitral Valve Regurgitation – Affects the left side of the heart and can lead to heart failure.
- Aortic Valve Regurgitation – Common in older horses, often causing a distinct “musical” murmur.
- Tricuspid Valve Regurgitation – Affects the right side of the heart, often seen in racehorses but usually not severe.
b. Congenital Heart Defects
Some horses are born with heart abnormalities that cause murmurs, such as:
- Ventricular Septal Defect (VSD): A hole between the heart’s ventricles, leading to abnormal blood flow.
- Patent Ductus Arteriosus (PDA): Common in foals but typically resolves naturally within days.
c. Endocarditis (Heart Infections)
Bacterial infections can cause inflammation of the heart valves, leading to murmurs and heart failure if left untreated.
d. Anemia and Dehydration
Low red blood cell levels or dehydration can increase blood turbulence, causing temporary murmurs that resolve once the underlying issue is treated.
How Are Heart Murmurs in Horses Classified?
Veterinarians classify murmurs based on their intensity, timing, and location within the cardiac cycle.
1. Classification by Timing
- Systolic Murmurs: Occur when the heart contracts.
- Diastolic Murmurs: Occur when the heart relaxes.
- Continuous Murmurs: Present throughout the cardiac cycle.
2. Classification by Intensity (Loudness)
Heart murmurs in horses are graded on a 1 to 6 scale:
- Grade 1: Very faint, barely detectable.
- Grade 2: Soft but easily heard.
- Grade 3: Moderately loud but not accompanied by a palpable thrill.
- Grade 4: Loud and may cause vibrations on the chest wall.
- Grade 5: Very loud with a strong palpable thrill.
- Grade 6: Audible even without a stethoscope, severe murmur.
How Are Heart Murmurs in Horses Diagnosed?
1. Physical Examination & Auscultation
Veterinarians use a stethoscope to detect and assess murmurs based on their location, duration, and intensity.
2. Echocardiography (Heart Ultrasound)
An echocardiogram provides real-time imaging of the heart to evaluate valve function, heart size, and blood flow abnormalities.
3. Electrocardiography (ECG)
An ECG (electrocardiogram) records the heart’s electrical activity to identify arrhythmias associated with heart murmurs.
4. Cardiac Biomarker Testing
Blood tests measuring cardiac troponins can help assess heart muscle damage in cases of suspected heart disease.
How Do Heart Murmurs Affect Horses?
1. Performance Horses (Racehorses, Eventers, and Show Jumpers)
- Mild heart murmurs often do not impact performance.
- Severe murmurs related to heart disease may cause reduced stamina, exercise intolerance, or collapse.
2. Breeding Horses
- Congenital murmurs may affect a horse’s ability to pass a pre-purchase exam for breeding.
- Certain conditions, like aortic regurgitation, are more common in older stallions.
3. Companion and Pleasure Horses
- Many horses with mild to moderate murmurs live normal, healthy lives without requiring intervention.
- Regular veterinary monitoring is essential to detect any progression.
Treatment and Management of Heart Murmurs in Horses
1. Monitoring and Lifestyle Adjustments
- Mild murmurs: No treatment needed, but require periodic checkups.
- Moderate murmurs: Exercise modifications may be recommended.
2. Medications for Heart Disease
- Diuretics (e.g., Furosemide): Reduce fluid buildup in cases of heart failure.
- ACE Inhibitors (e.g., Benazepril, Enalapril): Improve heart function and reduce strain on the heart.
- Digoxin: Helps regulate heart rhythm in cases of arrhythmia.
3. Surgical Interventions (Rare in Horses)
While surgery is common in human and small animal medicine, it is rarely performed in horses due to size, cost, and risk factors.
Frequently Asked Questions (FAQs) About Horse Heart Murmurs
1. Can horses with heart murmurs still compete?
Yes, many horses with mild murmurs perform well in racing, show jumping, and dressage. However, severe murmurs linked to heart disease may limit performance.
2. Do heart murmurs shorten a horse’s lifespan?
Not necessarily. Innocent murmurs have no effect, while disease-related murmurs depend on the underlying condition and treatment.
3. Should I buy a horse with a heart murmur?
A pre-purchase veterinary exam is crucial. Some murmurs are harmless, while others may indicate a serious problem. An echocardiogram can provide a clearer prognosis.
4. How common are heart murmurs in horses?
Studies suggest that 20-50% of horses have a detectable heart murmur, with most being benign and non-progressive.
5. What does “ghoda” mean in relation to horses?
“Ghoda” is the Hindi word for horse, commonly used in India and South Asia to refer to all types of horses, including racehorses and working horses.
Conclusion: Are Heart Murmurs in Horses a Cause for Concern?
Not all equine heart murmurs indicate disease. Many are harmless and do not affect a horse’s performance or quality of life. However, persistent or loud murmurs require veterinary evaluation to rule out serious cardiac conditions. Whether you own a racehorse, show horse, or companion horse, regular checkups ensure that your horse stays healthy and active.