Equine Guelph has announced a new video series detailing research results and now available on its new YouTube Channel.
The first in the series of informative monthly releases deals with Heart Disturbances in Horses:
Normal heart rhythm and sounds in a horse are difficult to define because of the array of strange sounds and rhythms which can be found in apparently healthy animals and which change with exercise. Also, even when sounds or rhythms do reflect heart problems, most horsepeople will not notice signs until the horse shows an unusual tendency to tire.
One aspect Guelph researchers Dr. Peter Physick-Sheard and Dr. Kim McGurrin look at is atrial fibrillation, the most common clinically significant rhythm disturbance in horses. An “arrhythmia” is technically defined as an abnormal heart rhythm. Irregular heart rhythm, however, is commonplace in horses and defining “normal” is apparently a complex process. In fact, even a completely steady rhythm can be considered abnormal.
A general physical examination is always made before any diagnosis of heart problems. An Electrocardiogram will assess the heart’s rhythm and then an Ultrasound to see how efficiently muscles and valves work may follow. Diagnosticians are looking for enlargement or any abnormal structure in the heart and checking for normal blood flow around the valves.
Dr. Physick-Sheard describes two types of rhythm disturbance that can be found:
1. Benign variations on normal (mostly involving the top part of the heart).
2. Ventricular rhythm disturbances, which can be serious and even life threatening.
When irregularities are found, first they check for problems outside the heart: dehydration, electrolyte and acid base imbalance. Under these circumstances secondary arrhythmias are often detected. Situations where cardiac problems are primary are rare, but can be serious.
McGurrin and Physick-Sheard have had enormous success treating arrhythmia with transvenous electrical cardioversion. While the horse is anaesthetized, electrodes are placed into the heart to deliver an electric shock to convert the rhythm to normal. The response rate with this s method of treatment has been an incredible 100 percent.
Dr. McGurrin and Dr. Physick-Sheard developed this technique before their first Standardbred track study, where they collected heart rhythm data during racing using an electrocardiogram.
Dr. Physick-Sheard has developed specialized equipment and software for the current intensive Thoroughbred study which he is hoping will give more insight into causes of sudden death.
Research funding on the subject of heart irregularities has been provided by Equine Guelph, Grayson Jockey Club Foundation and Ontario Ministry of Agriculture and Rural Affairs.
(With Files from Equine Guelph)