Heart Murmurs

Heart murmurs are abnormal sounds that can be detected amidst the normal heartbeats of your horse. These murmurs, although sometimes indicative of underlying issues with the heart, are often harmless. Interestingly, a study conducted on racing thoroughbreds revealed that murmurs were quite common, with only 1 in 10 horses not having an audible murmur.

What Causes Heart Murmurs?

The typical sounds produced by the heart, known as beats, result from the sudden changes in blood direction and speed as it is pumped through the heart. Heart murmurs, on the other hand, are any sounds that deviate from these normal beats. Many heart murmurs are not associated with any health problems. The unique anatomy of horses, such as their thin skin and lower heart rate, makes these non-problematic murmurs more frequently audible compared to other animals and humans. Additionally, these sounds can become more pronounced if the horse is excited or under stress.

However, murmurs may indicate a problem when the nature of the sound suggests that the heart’s ability to pump blood is compromised. Your veterinary surgeon can assess whether a heart murmur is of concern by examining its timing and characteristics within the heart’s normal cycle. Problematic heart murmurs can point to various issues, including blood leakage through the heart valves, thickening or narrowing of a blood vessel, or even a hole in the heart wall. The severity of the heart murmur generally correlates with the extent of the defect—the larger the defect, the more significant the murmur. For a more precise diagnosis, ultrasonography, which is available at some veterinary clinics and all referral centres, can be utilised. In the most severe cases, a heart murmur may be so pronounced that it can be heard or even felt without the use of a stethoscope.

What Are the Clinical Signs of a Heart Murmur in a Horse?

Most murmurs do not indicate a problem with the horse’s heart. However, in the rare instance that your horse does have a heart condition, the clinical signs will be related to disruptions in blood flow through the heart, which in turn affects the heart’s ability to pump blood efficiently throughout the body. If the defect causing the heart murmur is small, there may be no noticeable signs. Conversely, a larger defect may lead to a decrease in the horse’s performance and a reluctance to exercise. In severe cases, the horse may even refuse to exercise altogether.

If you suspect that your horse may have a heart problem, it is important to contact your Thrums vet for an evaluation. Heart murmurs, while often benign, can sometimes be a sign of more serious underlying issues, and a professional assessment is crucial to ensure your horse’s health and well-being.