Veterinarian, pediatrician team up to correct TOF in a canine

COLLEGE STATION, TEXAS—Veterinarians at Texas A&M College of Veterinary Medicine teamed up with a pediatric cardiothoracic surgeon in what is believed to be the first collaboration of its kind to repair a heart defect in Liz, a 10-month-old Labrador.

Drs. Theresa Fossum (front right) Kenneth Fox (back right) Sonya Gordon (front left) and David Nelson (center left) prepare to make the first incision on Liz to repair her TOF.

The procedure to correct the dog's defect, called Tetralogy of Fallot (TOF), took place Sept. 1 at the university and was conducted by Dr. Theresa Fossum, DVM, PhD, professor at Texas A&M, and Dr. Kenneth A. Fox, a pediatric cardiothoracic surgeon with Cardiothoracic and Vascular Association of Austin.

"We felt very good with the repair," Fossum says. "The heart looked beautiful after the repairs."

The team approached the surgery using a new technique and went to greater lengths to protect the heart while it was stopped.

Dr. David Nelson gives Liz a post-surgical examination while technicians Caleb Coursey (far left) and Galen Pahl look on.

"Dogs' hearts are more sensitive than humans', so we used a cardio polygenic solution to protect it for the 50 minutes it took to make the repairs," Fossum explains.

The four defects that are found in TOF are pulmonic stenosis, ventricular septal defect, overriding aorta and right ventricular hypertrophy secondary to the pulmonic stenosis.

Evidence suggests that these defects are the result of varying degrees of abnormality in a single developmental process—the growth and fusion of the conotruncal septum. It is possible that pulmonic stenosis or a ventricular septal defect, both of which occur independently, might be less severe manifestations of the same genetic defect.

Liz stayed on a ventilator for about 24 hours after the surgery but was eating independently the following day.

Dogs suffering from TOF will have a bluish color depending on the severity of their defect, Fossum says. Liz didn't have the bluish color, but she was less active than a dog her age is expected to be.

A severe murmur was discovered when Liz's owner took her to get routine vaccinations in August, and the veterinarian recommended further tests.

Despite the intensive care given to Liz, she died Sept. 21.

"She had an infection in her lungs and was being monitored by Dr. David Nelson at the university and his wife, Kate Nelson, a clinical perfusionist and professor," Fossum says. "By the time they reached the hospital, she had arrested," she adds. "The specific cause of death was a blood clot that entered her pulmonary artery."

Liz was the second dog to undergo TOF surgery for her own benefit.

Much was learned from Liz's procedure, Fossum says.

"Just like anything else, the more surgeries we do, the more we'll discover and understand about repairing the defect," she adds.

The university is expecting to perform another TOF surgery on a dog shortly, Fossum says.

The relationship between veterinarians and human doctors will continue to benefit animals, Fossum says.

"Pediatricians want to give back to the animals they were trained on," she adds.