Treatment of Equine Heart Arrhythmia

Human defibrillators are being used successfully to treat horses with irregular heartbeats (fibrillation). Kim McGurrin, DVM, a graduate student at the University of Guelph's College of Veterinary Medicine, developed a procedure as part of her doctoral research that can cure horses of an irregular heartbeat without the use of medication. The procedure has recently been implemented for the first time in the United States at the University of Florida and Cornell University.

"The most common cause of clinically significant irregular beat is atrial fibrillation," explained McGurrin. "If you visualize the horse and put a window in the side of the (fibrillating) horse, you would actually see the atria (the top chambers of the heart) look like a bowl of jelly vibrating. Once you correct the problem (with the shock from the defibrillator), the heart will contract smoothly."

The first horse treated with this procedure underwent its treatment in August of 2002 at Guelph. To date, 48 horses have been treated with a 98% cure rate, says McGurrin. Drugs have a cure rate of 80-85%.

The entire procedure takes about two hours. The technique involves threading two catheters fit with electrodes through the jugular vein in the horse's neck into the right atrium and pulmonary artery. An ultrasound is used to ensure the correct placement of the catheters.

McGurrin uses the Medtronics Lifepak 12 defibrillator to deliver the shock to the heart. "Paramedics carry the machine with them because it is so resilient," said McGurrin.

Recovery time from the treatment is minimal. "We ask the owner to leave the horse in the hospital for 24 hours, send the horse home with stall rest for 48 hours or small paddock turnout, then a week of light work, and then back to regular work," said McGurrin.

However, the problem can come back after the initial treatment, she said: "About 10-15% of horses will have an experience with the same arrhythmia again. We have treated four more horses again successfully."

McGurrin is planning on hosting a mini-symposium this fall at Guelph to train other veterinarians that might be interested in this procedure.

About the Author

Marcella M. Reca Zipp, MS

Marcella Reca Zipp, M.S., is a former staff writer for The Horse. She is completing her doctorate in Environmental Education and researching adolescent relationships with horses and nature. She lives with her family, senior horse, and flock of chickens on an island in the Chain O'Lakes.

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