Heart murmurs are caused by the blood flowing differently through the heart compared to normal. Some are more serious than others, either due to the type of blood flow abnormality or the severity of the condition. We may wish to investigate the murmur further to find out more about the abnormality. During anaesthesia, the heart and blood vessels are affected by the drugs we use, and this can change blood flow. In most animals with murmurs this change is not too significant although we need to carefully monitor the situation throughout anaesthesia. The risk of complications from anaesthesia can be higher in animals with heart murmurs but with our experienced anaesthesia staff we hope to minimise this.