Atrial fibrillation (AF) is the most common irregularity of the heart rhythm that will affect a horse’s performance. If the affected horse is not an athlete, it may be able to cope with this sort of cardiac irregularity, since the horse’s heart is a strong and efficient pump, so it can still push enough blood around for a horse to do light work, even if this pump is not working correctly.
AF is usually detected when a vet listens to a horse’s heart and detects an an irregular rhythm. The diagnosis can be confirmed with an ECG (electrocardiogram) where the electrical trace of the heart is measured. It is also possible to perform a cardiac ultrasound scan to identify any underlying heart disease. If there is anything else wrong as well, it all makes the prognosis worse for successful treatment.
Many cases do not need treatment as they return to normal heart rhythm on their own and hopefully never have further problems. The longer this irregular rhythm lasts, the more difficult it will be to revert to normal, so it makes sense to have your horse’s heart checked out if you have any concerns.
This article was first published in the 22 May issue of Horse & Hound magazine