The Horse With a Heart a Few Sizes Too Big…

Clydesdale’s Big Heart Skips More Than a Beat

By: Louisa Shepard/PennVet

Leading the team of majestic Clydesdales is Windsor, a special member of the eight-horse team that pulls a historic wagon for the Hallamore Corporation. So when he wasn’t himself, not pulling his weight, backing out of the harness, farm manager Ned Niemiec worried about Windsor’s heart.

Two other horses in the team had shown these signs in recent years, he said, and the diagnosis was atrial fibrillation causing an irregular heart rhythm. So when their primary vet suspected the same condition, Niemiec loaded up Windsor for the seven-hour drive from Lakeville, Massachusetts, to New Bolton Center.

“We’ve enjoyed a strong relationship with New Bolton for many years,” said Niemiec, who manages all aspects of the Hallamore Clydesdales. “We believe in the top, top reputation, especially in the cardiac area.”

Dr. Virginia Reef, Director of Large Animal Cardiology and Diagnostic Ultrasonography at New Bolton Center, is an expert in equine atrial fibrillation, known as a-fib for short.

“When a horse has a big heart, atrial fibrillation is more likely,” said Reef, who is also Chief of the Section of Sports Medicine and Imaging.

A Horse with Heart

Windsor, foaled in England, is a 12-year-old gelding that weighs more than 2,200 pounds and stands more than 18 hands high. “He’s huge,” Reef said.

Distinctive, with a large white blaze on his face, Windsor is one of 17 Clydesdales that live on the 40-acre farm of Dennis Barry, who for nearly 45 years has indulged his passion for the breed with his eight-horse hitch.

Barry owns Hallamore, a heavy-hauling transportation and equipment company that started in 1895 hauling loads with horses. To promote the company and foster positive public relations, a team of eight Clydesdales pulls an orange wagon, built in 1899, in parades and at local fairs.

“Windsor is one of the stars of our operation here,” Niemiec said. “He’s a wonderful horse. He’s one of the favorites in the barn. He’s not only handsome, he works well, too, and he has a great personality. Willing and attentive, alert and easy, he wants to do his job.”

There was no question that the Hallamore team would do everything they could to get Windsor the care he needed.

Cardiac Care at New Bolton Center

The electrocardiogram (EKG) confirmed the diagnosis of atrial fibrillation, Reef said. Windsor’s heartbeat was more than 80 beats per minute and didn’t settle down, compared with a usual rate of 50 beats per minute. Reef treated him with sotalol, an anti-arrhythmic drug with beta-blocking properties. “We wanted to slow the heart rate,” she said.

Reef and her team, including Dr. Fe ter Woort, a Fellow in Equine Cardiology and Ultrasound, also performed an echocardiogram (an ultrasound exam of the heart) and confirmed that Windsor did not have obvious structural heart disease, such as a leaking heart valve.

One of the ways to “convert” atrial fibrillation is to give the horse intravenous doses of quinidine gluconate, Reef said. This drug can be successful if the atrial fibrillation is new, and the horse does not have structural heart disease, like Windsor.

“We gave him small doses for a good part of the day, and the a-fib resolved,” Reef said.

The treatment worked, but the veterinarians had to watch for “premature” heartbeats, extra beats just before the regular beats. Windsor was on a continuous electrocardiogram around the clock.

“He did have a few atrial premature heartbeats,” Reef said. “And when he was on the trailer getting ready to go home, we heard a number of them.”

Windsor was sent home on the drug sotalol to try to suppress the atrial premature heartbeats. Reef also gave him benazepril, a drug that has been proven to help prevent re-occurrence of atrial fibrillation in humans.

In addition, she recommended potassium chloride supplements because the level of potassium excreted by Windsor’s kidneys was low. A potassium deficiency can cause the premature beats, and those premature beats can trigger atrial fibrillation, Reef said. “If the body is depleted of potassium, this can make it more likely for a-fib to occur,” she said.

Heading Home With a Heart Monitor

Niemiec went home with a 24-hour EKG to monitor Windsor’s heart. He did the recordings two weeks later, both standing in the stall, and while exercising, and sent the results to Reef.

Ultimately, they weaned him off the drugs and his heart rhythm stayed steady.

“He’s right as rain,” Niemiec said. “He seems to tolerate the work, whatever we ask him to do.”

Windsor’s heart has made it past the critical four-month period, which is when most relapses occur, Reef said.

“He’s past the first marker, which is good,