Pacemaker Recipient Gives Birth

A Thoroughbred/Irish Draught mare received a pacemaker in groundbreaking surgery at Great Britain's Royal Veterinary (UK) College's Sefton Equine Hospital in February. Seven-year-old Xena was weak and collapsing on admission to the equine hospital; she suffered from a rare heart condition known as third-degree heart block, which slowed her heart to a faint rhythm. In essence, her heart had lost its ability to regulate its own rhythm. Since the mare was due to foal in a few months, the decision to attempt the unusual surgery was made.

The surgery was performed under ultrasound guidance, without general anesthesia. A pulse generator was implanted under the skin on the mare's neck, with a lead through the jugular vein to the heart. The pacemaker was set to regulate the heartbeat at 40 beats per minute.

On July 5, Xena gave birth to a healthy bay colt named Vyper. As labor began, the surgeons increased the rate of the pacemaking device to 65 beats per minute to allow the mare to cope with the stress and exertion of foaling, then reduced the rate back to 40.

The foal was reported to be healthy and normal, and he returned with his dam to the owner a few days after foaling.

Most studies of cardiac disorders in horses are conducted in conjunction with the exertion of exercise or competition or on complications of the cardiac apparatus at birth.

"Xena's condition is uncommon and pacemakers have only been used a few times in the U.S., France and Holland," said Celia Marr, an RVC veterinarian, in an interview with Britain's Horse and Hound.

About the Author

Fran Jurga

Fran Jurga is the publisher of Hoofcare & Lameness, The Journal of Equine Foot Science, based in Gloucester, Mass., and Hoofcare Online, an electronic newsletter accessible at Her work also includes promoting lameness-related research and information for practical use by farriers, veterinarians, and horse owners. Jurga authored Understanding The Equine Foot, published by Eclipse Press and available at or by calling 800/582-5604.

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