December 15, 2008
Canine open-heart surgery coming to UC Davis
History of veterinary cardiac surgery suggests formidable challenges ahead
By: Edie Lau
For The VIN News Service
A new program in open-heart surgery for dogs starts in January at the University of California, Davis, School of Veterinary Medicine, under the leadership of an enthusiastic and energetic surgeon and cardiologist, Dr. Leigh Griffiths.
If history is a guide, Griffiths will need that enthusiasm, energy and a lot more to reach his goal of making heart bypass surgery routinely available and successful for dogs.
Griffiths and UC Davis are attempting a feat that during the past 30 years has confounded many another institution. High cost, the number of medical staff required for surgery and post-operative care, the time commitment required of staff, the types of conditions in dogs that call for surgery, and differences in how dogs respond to the operation compared with humans — these factors combined to stymie other programs.
“Minnesota, Pennsylvania, Tufts, Ohio State, California, Michigan State, Texas A&M, Colorado ... have all at one time had what they called an open-heart program,” said Dr. George Eyster, professor emeritus of medicine, cardiology, at Michigan State University and a pioneer in canine cardiac surgery. “No one’s doing it today, and that’s the legacy.”
UC Davis veterinary school is part of that legacy. A few open-heart surgeries were performed there in the early 1990s, but the cost — in money and time — spelled its end, according to Dr. Herbert Berkoff, a retired chief of cardiac surgery at UC Davis Medical Center who assisted his veterinary counterparts in the effort.
Griffiths is aware of the obstacles but undeterred. “I was in vet school when total hip replacement was expensive ... and the people doing it were really pioneers and thought of as somewhat crazy,” he said. “And now look at where that is. ... Many, many total hips get done all across the country every day of the week. I don’t see cardiac surgery as fundamentally any different.”
Dr. W. David Wilson, director of the veterinary teaching hospital, said UC Davis felt it could take on the challenge of bypass surgery because it already has a well-developed program in critical-care medicine to support procedures such as renal dialysis and “high-end” operations such as neurosurgery for brain tumors and adrenalectomies for endocrine problems.
“A critical factor here is to have a big enough critical-care ICU (intensive-care unit) support system with nursing staff, and have them sufficiently well-trained and adaptable so they can support cardiac surgery and also other needs,” Wilson said.
He noted that the downturn in the economy may, at the outset, shrink the potential pool of owners seeking cardiac surgery for their pets. On the other hand, the faltering economy has slowed demand for other services, as well, which means the ICU staff is more available.
“They want to be busy,” Wilson said. “Rather than cutting the size of the staff, the other option is to do more things. This is actually a good time to be doing (cardiac surgery), from that perspective.”
In leading the new program, Griffiths is driven by awe over the heart’s tenacity and a desire to offer companion animals the same shot at life that people get. His motivation was born of experiences in his veterinary school days and before.
“Open-heart surgery is such an amazing thing to do. I feel like it’s one of the new seven wonders of the world — the fact that you can stop the heart, and an hour or two later, just let it beat (again). That thing just likes to beat,” he said. “When I saw open-heart surgery in humans, I was like, ‘Wow, this is just amazing,’ That became my goal for my life, basically; to do it for animals.”
Griffiths, who grew up in Great Britain, has long felt that pet owners should be able to obtain the same medical treatments for animals that are available to people. As a teen-aged animal-lover job-shadowing a veterinarian, Griffiths remembers seeing a cat come in after being hit by a car, and hearing the veterinarian tell the owner nothing could be done to save its life.
As an adult, Griffith believes the veterinarian responded appropriately, but he remembers thinking to himself at the time, “If this was a human, we wouldn’t do that.”
“That’s been a driving force for everything I’ve done,” he said. “Not necessarily that everyone should choose open-heart surgery for their dog, but that it should be a choice. I would like the profession as a whole to have as many options as we can. Also, that any care that’s standard for humans should be standard for our clients.”
Getting there is easier said than done.
Two institutions with the most recent experience offering open-heart surgery for pet dogs — Colorado State University and Texas A&M University — recently suspended their programs.
Colorado, where Griffiths was trained, had the longest experience. Between 1991 and the spring of this year, the program performed somewhere between 100 and 200 bypass surgeries, according to its leader, Dr. E. Christopher Orton.
Orton said multiple factors caused him to stop taking most cases (he’ll still consider in-state cases under certain circumstances but won’t take patients outside Colorado). In short, demand for the service outpaced the program’s ability to provide it, he said.
“While the program was open, I’d get three to four e-mails a day from people desperately wanting open-heart surgery,” Orton said. “This university was not able to give us the resources...
“For veterinary schools with limited resources to have that many people devoted to a single patient is very difficult,” he said. “At any given moment, during the surgery, you’re talking about six to 10 people. Immediately afterwards and for the first 48 hours, you may be talking about a different six to eight people. ... It takes close to two weeks to get (the patients) in and out the door. And I have other responsibilities besides surgery.”
This, for an operation for which Orton never quoted better than 80 percent chance of success — and sometimes much less, depending on the case.
The highly uncertain outcome makes it more difficult for owners to justify the expense, which cardiac surgeons said ranges from $10,000 to $18,000. Griffiths estimated the cost at the lower end — $10,000 to $12,000 — while acknowledging that is still a lot of money.
He is confident the program nevertheless will attract takers. “We have people for whom these are, in effect, their child,” Griffiths said. “They chose not to have children and got a dog instead. ... There’s a whole range of reasons people do this.”
And not all are rich, he added. “I've operated on dogs where the person is unbelievably wealthy. I’ve equally operated on a dog where the person had no money and literally set up a website where they solicited donations for the dog,” he said. “We have people who put the surgery on a credit card. Obviously, it’s great when the patient is insured.”
The history of bypass surgery on dogs reaches back decades to the early days of bypass surgery in people. Eyster at Michigan State, who in the 1960s became the first surgeon to perform a heart valve replacement in a dog, said his team learned by working on human cases. At the same time, the team used research dogs to work out techniques for humans.
In those days, open-heart surgery was cheap and primitive. “I could do it for less than $200 (in) equipment,” Eyster said, recalling the use of bubble oxygenators that crudely brought oxygen to the patient’s blood using an inexpensive device that could be sterilized and reused.
When medical science came up with membrane oxygenators that better mimic the action of lungs and treated the blood cells more delicately, patient survival greatly increased, but so did the cost of surgery, Eyster said.
Then AIDS came along, and one-time-use, disposable equipment became the norm, pushing up costs further. (Although acquired immune deficiency syndrome in people isn’t a risk for dogs, no one makes equipment just for dogs, so veterinary surgeons must use human equipment, Eyster noted.)
Meanwhile, the rising success rate of bypass surgery in people has not translated directly to dogs. Differences in their physiology make dogs respond differently. Their red and white blood cells are more sensitive to insult, for example, and their vascular tissues don’t hold sutures as well as human tissues, surgeons said.
Then there’s the simple fact that veterinarians can’t communicate with their patients as human doctors do. “The dog doesn't understand,” said Berkoff, the retired human cardiac surgeon. “It can’t take deep breaths and stuff as the human can when told to, which is so important for recovery.”
Furthermore, dogs tend to need heart surgery for reasons different from people. The most common problem in dogs is mitral valve disease, in which one of the four valves of the heart that control blood flow fails to close tightly, becoming leaky. It’s a condition that develops with age. Eyster said one in 12 dogs over age 5 has mitral valve disease. It’s seen more often in small dogs, which happen to be harder to operate on. It also tends to occur in older dogs — around age 10 — making the expense that much harder to justify.
Mitral valves degenerate in people, too, but far greater in humans is the incidence of coronary artery disease, Berkoff said. Around 300,000 bypass surgeries a year in the United States are done for clogged or hardened arteries, compared with about 60,000 a year for valve problems, he said.
“When you’re on the pump doing coronary bypass, you’re not inside the heart (as with valve surgery) — you’re on the surface and adding more blood to the heart,” which should bring immediate improvement to the heart condition, Berkoff said. “With valvular stuff, the recovery is usually a little harder and a little more complicated.”
While veterinary medicine struggles to make heart bypass a standard of care for dogs, human cardiac medicine is moving away from invasive chest-opening surgery in favor of operating with catheters, which require only small incisions. But common use of catheters is years off, Berkoff said.
Meanwhile, common wisdom in human cardiac bypass surgery says that the more cases an institution (or given surgical team) performs, the better its success rate. With that in mind, the UC Davis team is aiming for 100 cases a year — all clinical, none research. That’s a medium-term goal that probably will take five to 10 years to reach, Griffiths said. For the first year, he hopes to do 10 to 15 cases.
The lower number is more in keeping with what has been accomplished elsewhere. Orton said the most surgeries his team performed in a year was about 20.
But Japan, which veterinary cardiac experts say is the best in the world at this game, is proving that higher numbers are possible to pull off. Dr. Masami Uechi at Nihon University reported doing about 80 cases over the past four years, almost all mitral valves, and 62 of those cases in 2007 alone.
Uechi said in an e-mail response to questions that his patients are small dogs weighing between three and 30 pounds. He’s also operated on four cats. Of the dogs, he said that 92 percent have made it at least one month past surgery, their symptoms resolved and needing almost no medication. “Owners were happy,” he said.
Dr. John Rush, a veterinary cardiologist at Tufts University recently visited the team at Nihon. He called their performance impressive. “Certainly their results provide me with some optimism that a durable result (one year or greater) can be achieved in a reasonable proportion of cases,” Rush said in an e-mail.
(Tufts began offering bypass surgery in 2001 but has since stopped doing mitral-valve cases and is taking only some congenital defects, Rush said; it has done no operations in nearly two years.)
In addition to UC Davis, Michigan State University is will be offering open-heart surgery once again. Lead by Dr. Augusta Pelosi, who trained under Eyster, that program will involve a mix of research and clinical cases. Pelosi said she hopes to begin taking patients next fall at the rate of one or two per month, while working on an equal number of research animals. (She said the research cases are terminal and therefore do not require post-operative critical care.)
In sum, open-heart surgery in dogs is doable, but difficult: “Can it be done?” said Eyster. “There’s no question about it. Is it feasible? Certainly. (But) it’s a lot more work than anyone would ever think.”
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