Last week saw tragedy at the World Equestrian Games in France when a British team horse collapsed and died after completing a clear cross-country round in the three day event. A post-mortem will be held to determine the cause of death, but the horse’s rider reported that ‘Wild Lone’ was still full of running as he finished the course and did not feel at all tired.
But what could have caused a fit, healthy equine athlete to die so suddenly in such tragic circumstances? There is speculation that a heart defect could be to blame. How do you recognize a heart defect in your horse, how serious could it be, and will you still be able to ride him safely? Read on to find out more.
Many horses have a heart murmur. It’s an abnormal sound originating from one of the heart’s valves that your vet can hear through a stethoscope.
Are all murmurs the same?
The majority of heart murmurs are thankfully not due to any significant abnormality and are just caused by the normal flow of blood through the heart. Some murmurs however do indicate a problem with blood flow or heart function such as: a leaking valve, a thickened or narrowed large blood vessel or heart valve or an abnormal hole between two chambers of the heart.
How can I find out if a murmur is due to a significant problem?
Most heart murmurs are found during routine examination by a vet. In almost all cases, the animal has not shown any clinical signs of disease or problems with its heart.
Signs of heart problems, if they are present, can include: reduced tolerance of exercise, thickening of limbs and lower neck and chest, and enlargement of the blood vessels causing a visible pulse in the jugular vein.
Your vet will carry out careful auscultation (listening to your horse’s heart with a stethoscope) and this together with any presenting clinical signs of heart disease will enable him to localize the murmur. This will give some indication of whether the murmur is due to a serious problem.
In some cases, it’s necessary to carry out further investigations to determine whether the murmur will get worse or if it presents a performance-limiting problem.
Blood tests can reveal if there has been damage to the heart muscle.
Heart abnormalities of size and rhythm can be detected using an electrocardiogram.
The most informative procedure available is an ultrasound examination of the horse’s heart. Your vet will be able to study images of the heart whilst it is beating enabling measurement of the chamber size and movement, and observation of the valves opening and closing.
In problem cases, the valves may not function correctly or may be abnormally thick, or the heart chambers might not pump efficiently. Ultrasounds would be recommended if a murmur was detected during a vetting for purchase, particularly if the horse was intended to be used in strenuous disciplines such as racing or eventing.
It will often be necessary to repeat examinations at intervals to monitor any changes in the structure and performance of the heart and to give an idea of whether the condition is likely to worsen over time. Very often, in the case of young horses and foals, a heart murmur detected can disappear over the course of a year or so as the organ develops and the horse reaches maturity.
What is the outlook for my horse if he has a murmur?
Most horses with heart murmurs are fit and healthy and remain unaffected in their performance; my very first horse had a heart murmur which didn’t stop him hunting, eventing, and enjoying beach rides and hunter trials. In some cases however, the abnormality may worsen over time.
Sometimes, a murmur may be a temporary side-effect following a viral infection. This is not common and usually rectifies itself after time off for rest during which the cardiac muscles repair themselves.
Heart murmurs in horses cannot be treated surgically or medically. Sometimes, it may be necessary to reduce the level at which the horse is expected to work or compete, and in some cases where cardiac abnormality is severe, it might not be safe to ride the horse and he should be retired.
If your horse exhibits any of the signs of possible heart problems, always get him checked by your vet, and don’t be tempted to continue riding him until he has been given the all-clear.
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