Credit: Provided

Veterinarians from three countries joined forces with Cornell University Hospital for Animals (CUHA) to save a young German shepherd’s life after a bundle of tissue in his heart turned deadly.

At six months old in 2017, Rex was by far the calmest dog the Silverman family of New York City had ever owned. Their other German shepherds all bounced off the walls at that age, so at first they attributed Rex’s docile behavior to temperament.

“He was very low energy compared to the others,” said owner Karen Silverman. “I just thought he was lazy, that he liked to cuddle all the time instead.”

Nothing in his regular check-ups indicated a problem, but when Rex became violently ill in December 2017, the Silvermans noticed the dog’s heart was racing – and knew it was something far more serious.

Gretchen Singletary, a veterinary cardiologist in New York City, stabilized him and performed a series of tests, including an electrocardiogram that confirmed the presence of an arrhythmia, a condition that causes the heart to beat abnormally.

The culprit: a small bundle of muscle running inside the wall of his heart, a defect Rex was born with and likely caused his low energy. Singletary told Silverman that Rex was a candidate for a procedure that can cure some arrhythmias in dogs: radiofrequency catheter ablation, where small areas of the heart muscle are heated through the tip of a catheter to destroy abnormal tissue. It’s simple on paper, but not in practice. The complicated, precise procedure requires a high level of skill. Only two places in the United States offer it routinely – a private practice in Ohio and CUHA.

Once Silverman knew Rex had a chance at Cornell, she brought him to Ithaca that night. “I was going to do whatever it took,” she said.

Collaborations in cardiology

When Rex arrived at the College of Veterinary Medicine, the cardiology team quickly controlled his skyrocketing heart rate and assessed the situation. They agreed – he needed the ablation, and only the right mix of medicine would keep his heart rate at normal levels until they could do the procedure.

“We knew the tachycardia would come back quickly if he didn’t have those medications,” said Romain Pariaut, associate professor in the Department of Clinical Sciences and section chief of cardiology at the hospital. Pariaut, a native of France, did his residency at Cornell and joined the faculty in 2015.

Pariaut provided a detailed explanation of the procedure for Silverman’s 7-year-old son, who knew him as "Dr. France," said Silverman.

Soon they would add a "Dr. Italy" to the mix. Italian cardiologist and adjunct professor Roberto Santilli is one of the few veterinarians in the world who can perform the catheterization component of the ablation, which guides the catheters through the jugular and femoral veins and delivers the heat blasts to their target in the heart. Although Santilli was in Italy when Rex fell ill, he rushed to Ithaca five days after Rex arrived. With Pariaut, members of the Cardiology Section and a lineup of CUHA residents and students, this international dream team prepped the puppy for the procedure.

Precision procedure

While they knew what caused the arrhythmia, finding the exact location of the abnormal muscle bundle in Rex’s body was challenging. “It was difficult to spot the bundle, which is also known as [an] accessory pathway,” said Pariaut, “and we were coming closer and closer to the atrioventricular (AV) node, which we didn’t want to damage.”

Damaging the AV node would be a serious complication that could affect Rex’s long-term quality of life and require a pacemaker, which have grim success rates for dogs his age. The Cornell team found that the bundle of tissue rested just next to this sensitive area. When Pariaut informed Silverman of the danger, she insisted they proceed.

With Santilli guiding the catheters and Pariaut signaling timed blasts to break up the accessory pathway, the doctors managed to burn the problematic area without damaging the nearby AV node. “I knew they could do it,” said Silverman. “We had the greatest team. Everyone came together and made a miracle happen.”

Credit: Provided

Silverman was enthusiastic about the success of the procedure. “Six hours later he came running down the hall, and the next day he came home with me,” she said. “It was the most amazing thing.” Within one month he was up to a healthy weight.

Now that a few months have passed, the risk of the tissue recreating the arrhythmia diminishes each day. Since then, the cardiologists at the hospital have re-examined his heart to confirm that it is beating normally. Rex’s heart is much stronger, according to Pariaut.

Rex, still not even a year old, can now enjoy puppy life to the fullest. In honor of his successful recovery and the surgeons who made it possible, the Silvermans partnered with the cardiology team to create the Henry and Karen Silverman Initiative to Advance Treatment of Canine Arrhythmias, housed within CUHA. Their intention is to further the study, diagnosis and treatment of arrhythmias in dogs, as well as to educate pet owners and veterinarians about these treatments for heart rhythm disorders. To learn more about this initiative, contact Amy Robinson at 607-253-3742.

“Now all he does is run,” said Silverman. “He finally has the energy to play.”

Melanie Greaver Cordova is a staff writer at the College of Veterinary Medicine.