The heart of the matter

We all love big-hearted horses – believing them to be kind, bold steadfast and willing to try their best with whatever the rider asks. But what does this term really mean and what is the true size of a horse’s heart? Are some bigger than others and how hard do they have to work to keep our amazing equine athletes in action?

Heart size

The average horse’s heart is the size of a large melon and weighs around 8-10lbs which is equivalent to the weight of a small dog. In some cases they can weigh double this but it doesn’t always mean that the horse will be a better performer – many other factors have to be considered when it comes to the athletic ability of our equine friends.1,2,3

Heart work

The heart is a muscle and it contracts in a rhythmic cycle – giving it a distinctive beat.4 In the horse it is a cone-shaped organ, broad at the top and with the tip lying near the horse’s sternum.

It has four chambers. Blood enters the heart via the right atrium and flows into the right ventricle. From here the pulmonary artery takes it to the lungs where it is oxygenated before entering the left atrium and then the left ventricle. It is then pumped round the horse’s body via the aorta at a rate of around 35 litres per minute at rest. 3,4