Cardiovascular System 
e.g. abnormal heart function such as abnormal heart rhythm or
poor performance
Echocardiography
Ultrasound of the heart provides a lot of vital information about heart function and structure. Ultrasound can be used to look at how well a heart is contracting and how well valves are functioning. A special Doppler colour mode function enables us to look at the direction of blood flow throughout the heart and determine the source of a murmur, whether this is due to blood turbulence or a problem with a heart valve.
ECG
Electrocardiogram (or ECG) detects electrical currents in the heart. The ECG is used in horses to assess heart rhythm. Abnormal heart rhythm can affect a horse’s ability to exercise and perform. The treatment used depends on the type of arrhythmia and the findings on echocardiography.
Telemetry
Sometimes horses may only have abnormal heart rhythm in association with exercise, or it is unclear if an arrhythmia detected at rest is significant during exercise. Telemetric electrocardiography during exercise facilitates investigation of heart arrhythmias. This technology is similar to that used with modern heart rate monitors. A radio signal is transmitted from electrodes placed on the horse’s chest and is collected by a device that the converts the signal to an ECG. These signals can be recorded and directly observed while a horse is exercising, either on our high-speed treadmillor by lunging or riding the horse.
Holter monitor
The Holter monitor is a 24-hour continuous recording of a horse’s ECG. It permits recognition of any rhythm problem of the heart that may occur periodically throughout the day. Special leads are placed on the horse’s chest and attached to a small tape recorder that is hooked to a special girth. While wearing the Holter monitor, the horse is observed closely so that any unusual behaviour is recorded for later comparison to the findings of the Holter monitor.
After the monitor has been worn for 24 hours, it is taken off and sent to a hospital for analysis. The taped ECG is scanned electronically to see if there are any abnormal heartbeats.
