OREGON STATE UNIVERSITY

Pooch pacemakers? Canine cardiology gets a boost at OSU…

03/15/2010

CORVALLIS, Ore. – Older dogs with slowing hearts – and young dogs with congenital heart defects – are getting a new lease on life at Oregon State University, where advanced technology and new treatment protocols have created an emerging cardiology program in the College of Veterinary Medicine.

During the past five years, OSU has developed a growing reputation for its cardiology program, which college leaders say is now in the “upper echelon” of programs nationally. On any given week, it isn’t unusual to see an older Labrador retriever being fitted with a pacemaker, or a young spaniel treated for a heart defect it has carried since birth.

What makes the OSU program unique is instrumentation that is, perhaps, the best of any university in the country, says David Sisson, a professor of veterinary medicine who runs the cardiology program.

“The 64-slice CT (computed tomography) scanner we have is frankly better than those in most human hospitals and the fastest scanner in use by any veterinary medicine facility in the United States,” Sisson said. “We can scan a dog’s entire heart in 15 seconds and see every blood vessel.

“Seeing the problem,” he added, “is 90 percent of the solution.”

Because of the technology and faculty expertise, procedures that used to be complicated are now becoming routine. Defects that used to require surgery are being treated through minimally invasive techniques that are not only easier on the pets – they frequently are less expensive. And the OSU College of Veterinarian is taking more and more referrals from veterinarians around the Northwest to treat difficult cases.

Take Piper, for example.

The eight-month-old Sheltie, owned by John and Denise MacDonald of Abbottsford, B.C., went in for the standard “puppy checkup” at their local veterinarian, who discovered he had a heart murmur. By the age of six months, Piper’s murmur had worsened, so the MacDonalds took him to a canine cardiology specialist in Vancouver, B.C., where he was diagnosed with “patent ductus arteriosus,” or PDA, a congenital heart defect in which a blood vessel in the heart that is supposed to contract after birth instead remains intact and must be closed. If the case is severe, the heart can become overworked and the dog can develop heart failure and die.

When a surgeon began working on Piper, however, the Sheltie began hemorrhaging and the operation was aborted.

“It took him three weeks to recover from the procedure and he still wasn’t fixed,” said Denise MacDonald. “He was pretty out of it for most of that time; I guess getting your chest cut open will do that to you. The anesthesiologist there knew of Dr. Sisson and his work with dogs with bad hearts, and worked as a liaison to set up an appointment.”

Sisson said a second surgery would have been complicated because scar tissue in the area would have increased the chances for a fatal rupture of the blood vessel. But Sisson and his colleagues have gained a reputation for alternative minimally invasive procedures – including for PDA.

After getting a variety of images using the college’s CT scanner, color flow Dopper echocardiograph, and fluoroscopy unit, Sisson performed a procedure in which he used a small cable inserted through an artery in Piper’s hind leg to plant an expandable nickel-titanium mesh screen called an “Amplatzer duct occluder” to block the artery and essentially close it. The entire procedure took less than 90 minutes and Piper was bounding out the door the next morning to greet the MacDonalds.

No surgical cutting. No long recovery.

“Twenty-five years ago,” Sisson said, “this would have been a difficult case to treat. Ten years ago, we probably would have tried surgery, too. Now we do minimally invasive procedures whenever possible, which is a win-win situation for the pets and their owners.”

About one or two dogs in every 1,000 will have PDA, Sisson said, so the procedure is becoming more common. OSU’s College of Veterinary Medicine also inserts pacemakers into older dogs with heart conduction disturbances and treats other cardiac abnormalities that occur most often in dogs that are specially bred.

The veterinary clinicians also treat cats with heart problems. “Hypertension is a significant problem in adult cats, and often requires treatment,” Sisson said.

Inserting a pacemaker into a family pet may seem like an expensive proposition, but it is less than one might think. The reason?  A program called the Companion Animal Pacemaker Registry and Repository, which Sisson began 20 years ago, gets the pacemakers for about 10 cents on the dollar.

“The pacemakers we use in animals are the same ones used in humans, which cost about $3,000,” Sisson said. “But under U.S. laws, the pacemakers can’t be used on humans if they sit on the shelf too long because the longevity for batteries is about eight to 12 years. However, that’s plenty long enough for dogs. So we approached the manufacturer and initiated a donor program.”

Not only is the OSU College of Veterinary Medicine building a reputation for cardiac care, it is training a new generation of students these minimally invasive techniques.

However, Sisson adds, there is a limit to what the OSU veterinary doctors will do.

“We don’t do open-heart surgeries,” he said. “It would require assembling eight-person teams and cost a minimum of $20,000 and at that point we have to say that directing those kinds of resources toward (the pets of) just a few people who can afford it isn’t what our college is about. Heart transplants for dogs cross the limits of what we want to do.”