Tests confirmed the lethargic 8-month-old golden retriever had subaortic stenosis. Only a few years ago, treatment consisted of medical management or surgery to remove scarring in the narrowed aortic valve.
More recently, specialists have used balloon valvuloplasty to break up the obstructions. All three treatments show varying degrees of effectiveness.
Last year at the College of Veterinary Medicine at the University of Florida, doctors used a new device, a balloon fitted with blades. The case was remarkable for more than its success in restoring the patient to high-spirited good health.
It combined the skills of a veterinary cardiologist and a pediatric cardiologist: Amara Estrada, DVM, chief of the cardiology section at the school, and Joseph A. Paolillo, MD, a colleague from Shands HealthCare and director of the congenital catheterization program at the sprawling UF-affiliated hospital complex a brisk 10-minute walk away.
Courtesy of the University of Florida
Dr. Amara Estrada, left, and former University of Florida internal medicine resident Dr. Nikki Hackendahl hold the barbecue skewers that were removed surgically from Yankee's heart in a collaborative procedure involving UF veterinarians and cardiologists and cardiologists from Shands Hospital in Gainesville, Fla.
Their continuing collaboration is part of a new discipline called translational medicine.
“These collaborations are huge right now—the wave of the future,” says Meg M. Sleeper, VMD, section chief of cardiology at the University of Pennsylvania School of Veterinary Medicine, renowned as the birthplace of veterinary cardiology.
While breakthroughs in imaging, pharmacology and interventional surgeries using coils and catheters have improved the lives of dogs and cats with heart disease, advocates of translational medicine predict it will have even greater impact, enhancing the health of both people and animals.
“The ability to interact with our human pediatric colleagues to use veterinary patients as a model for disease in people benefits both tremendously,” Dr. Estrada says. Interaction between UF medical and veterinary schools occurs almost daily.
Though TM has various interpretations, including “one medicine,” veterinarians often use the term to describe their growing partnership with scientists and medical doctors. Together, they translate research into clinical application.
“It takes a team for science to move from the cell to the cage side,” says N. Sydney Moise, DVM, MS, chief of the cardiology section at Cornell University and co-editor in chief of the “Journal of Veterinary Cardiology.” Cornell’s cardiology section has emphasized translational science in its research program for more than 20 years.
“The emphasis has not only enhanced the research but resulted in all finishing cardiology residents pursuing academic positions and raising the standard for clinical practice,” Dr. Moise says.
But she and Robert Hamlin, DVM, Ph.D., at Ohio State—both internationally known cardiologists—believe TM raises some questions. More research is needed overall, particularly on heart disease in cats, Moise says, but she views the trend of higher-paying corporations buying centralized specialty practices as a potential problem in linking basic scientists and clinical cardiologists.
“Close proximity to each other is needed for the interaction of persons driven to research, but if the number of young cardiologists interested in collaborative research with the fundamental scientist decreases as they go to exclusive practices,” she says. “Such situations may draw away the young cardiologists from academia. Who’s going to be the next generation with the enthusiasm to pursue research?”
Dr. Hamlin also has concerns about TM.
“The challenge will be to deliver evidence that its findings translate into clinical improvements,” he says. “We should practice it only when it translates into longer life or a better quality of life.”
Answers to both concerns aren’t immediately forthcoming, of course. Meanwhile, the College of Veterinary Medicine at North Carolina State has more than 100 researchers from its teaching hospital and five North Carolina colleges participating in work at its Center for Comparative Medicine and Translational Research.
Its cardiology research focuses on developing clinical trial methods and tools to answer questions about dogs and cats with spontaneous heart disease, says Bruce Keene, DVM.
“Drs. Clarke Atkins, Teresa DeFrancesco and I, in addition to others at NCSU and several other centers in the U.S., collaborate in this work,” Dr. Keene says.
At Virginia-Maryland Regional College of Veterinary Medicine, plans are proceeding for a $70 million building devoted to translational medicine, and TM studies are under way around the country. At the University of Florida, researchers are exploring stem-cell therapy for heart disease.
“This started with a rat model, now pigs and soon veterinary patients, with funding coming largely because of the hope it will help children and adults, but both sides will benefit,” Estrada says.
Along with their counterparts at the University of Pennsylvania School of Medicine, researchers at the veterinary school are studying gene therapy for dogs with heart disease and will eventually study cats, Dr. Sleeper says.
“We’re stuck now treating heart failure medically to try to maintain a plateau of function, while the goal with gene therapy is to transfer a gene which will produce a protein product that addresses the underlying metabolic basis,” she says.
But there’s no denying the impact of new drugs, she says. “Changes in recent years that allow us to better treat heart disease are mind-boggling.”
As do colleagues, Hamlin cites a new medication as the most significant advancement in cardiology: “Clearly, it’s the novel-acting drug pimobendan [Vetmedin]. It’s been shown to lengthen life and decrease symptoms.”
The FDA last year approved the drug for dogs with mild, moderate or severe atrioventricular valvular insufficiency and dilated cardiomyopathy. Furosemide is the only FDA-approved drug for cats with heart disease (it’s also used in dogs). Veterinarians use a host of drugs for cardiac disease off-label, including sildenafil, billed as “Viagra for dogs.”
Cardiologists also hail the development of diagnostic tools as an important advance. Penn boasts an array of equipment, including electro- and phonocardiography, Holter-monitoring and a pacemaker interrogator unit. In 2004, it became the first veterinary school to acquire a Philips Sonos 7500 imaging system to provide real time 3D echocardiography.
While such high-end tools aren’t necessary in general practice, Sleeper urges practitioners to stay current about new developments in cardiology.
“This is such a rapidly evolving field. For a lot of people, it’s surprising what we can do,” she says, adding that practitioners shouldn’t hesitate to call cardiologists at universities or referral centers for advice.
An aphorism from Louis Pasteur, via Dr. Moise, applies: “Fortune favors the prepared mind.”
Nutritional intervention—particularly the use of supplements—can play an important role in managing feline and canine heart disease. N-3 fatty acids, also known as omega-3 fatty acids, have been proven to decrease inflammatory cytokins, which contribute to physical wasting in dogs with congestive heart failure, says nutritionist Sally C. Perea, DVM, MS, a consultant with Davis (Calif.) Veterinary Medical Consulting.
“By incorporating long-chain polyunsaturated n-3 fatty acids into the diet, we may be able to reduce the negative effects of inflammatory cytokines,” she says.
Research on dogs with early chronic valvular disease has shown the benefits of restricting sodium and feeding a diet enriched in antioxidants, n-3 fatty acids, taurine, the amino acid arginine and L-carnitine.
No controlled studies have proven the efficacy of the supplement L-carnitine, though some anecdotal reports on dogs with dilated cardiomyopathy have been positive.
Because it helps convert fatty acid into energy and the heart relies on fat metabolism to generate most of its energy, L-carnitine is needed for healthy myocardial function, Dr. Perea says.
Dogs and cats can synthesize L-carnitine, so it’s not an essential nutrient.
“In some cases, however, a carnitine deficiency has been associated with familial myocardial disease in boxers,” Perea says. She recommends L-carnitine and taurine supplementation for dogs with dilated cardiomyopathy. Both offer potential benefits without negative side effects.
Because of the health risks associated with cachexia, Perea also urges practitioners to ensure that pets with congestive heart failure receive adequate calorie and protein intake as part of their nutritional therapy.
Betty Liddick, a writer in Venice, Fla., also edits Your Dog, a monthly newsletter from Cummings School of Veterinary Medicine at Tufts University.