UF College of Veterinary Medicine
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Florida veterinarians become first in U.S. to perform electric shock treatment to correct horse's heart arrhythmia

by SARAH CAREY

      The horse who received the March 29 procedure, is a 2-year-old Standardbred owned by the UF veterinary college. The horse had been treated medically for irregular heartbeat in the past, but the arrhythmia kept returning.

     Within the past month, the UF team had been trained in the procedure by the veterinarian who developed it. University of Guelph veterinarian Kim McGurrin, DVM., visited Gainesville to provide the procedure to a horse from Ocala . Just weeks later, UF's equine medicine veterinarians and veterinary cardiologists collaborated to put into practice what

they learned.

     McGurrin developed the cutting-edge technique over the last four years along with her mentor, Peter Physick-Sheard, B.V.Sc., at the University of Guelph .

     “We developed this procedure to offer new treatment options for atrial fibrillation, and it is excellent that UF is now cabable of performing this procedure,” McGurrin said. “We have applied this technique over 50 times, including 44 client-owned horses, several of which were referred from the States. Most horses have returned to performance and we now consider this procedure routine.”  

      Amara Estrada, D.V.M., an assistant professor of veterinary cardiology at UF's College of Veterinary Medicine , and her colleague, Darcy Adin, D.V.M., were both involved in the recent UF procedure. Estrada described the cardiac abnormality for which the procedure is used as “an important arrhythmia for many reasons.”

     “Probably it is most important to horse owners and trainers of race horses because it causes poor performance and poor racing,” Estrada said. “But certainly pet horses develop the condition as well.”

      She said irregular or fast heart beat, also known as atrial fibrillation, causes a decrease in cardiac output, negatively impacting a horse's performance.The disease is said to be frustrating to both horse owners and veterinarians because medical therapy frequently has to be administered many times and often has serious side effects.

     “Typical medical treatment has consisted of antiarrythmic drugs given orally or intravenously, but the drugs can have fairly significant side effects, including toxicity,”said Steeve Giguère, an associate professor of equine medicine at UF.

     The UF veterinarians had heard of McGurrin and the fact that intracardiac electrical conversion technology was now being performed in horses at the University of Guelph routinely with “great success,” Giguère said.

      The procedure, which takes about two hours, involves surgically placing two catheters through veins in the horse's neck into specific chambers within the heart -- the right atrium and the pulmonary artery. During the catheter placement, echocardiography, or ultrasound technology, is used to determine the exact placement of the catheters.

     “Once the catheters are in the correct location, a short shock is delivered to ‘reset' the atria and terminate the fibrillation, thus establishing a normal rhythm,” Estrada said.

     The equipment used to administer the shock is a biphasic defribrillator, the same technology used in human emergency medicine to treat cardiac arrhythmias.

     “Atrial fibrillation is the most common arrhythmia of horses, occurring in 1 to 2 percent of all horses,” Giguère said. “Most horses with atrial fibrillation do not have underlying heart disease, however, so if you can restore their normal sinus rhythm, they usually return to their previous level of performance.”       

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