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Professor of Cardiology and Cardiothoracic Surgery Developing Treatment for Mitral Valve Disease in Dogs

 

The greatest gift that Dr. Christopher Orton can give to a student of veterinary cardiology is confidence. It’s very difficult to detect the first symptom of the most common cause of heart disease in dogs: a heart murmur. When the student puts her stethoscope to a dog’s chest and tries to detect the whooshing or rasping sounds of turbulent blood, she may struggle to hear anything other than the heartbeat. It takes time, experience, and confidence to identify the first telltale sign of mitral valve disease.

Mitral valve disease is the most common cause of heart disease in dogs, affecting 2.5 million to 5 million dogs in the United States. It also affects 2 percent of the human population. The canine heart is very similar to the human heart, with four chambers connected by valves that prevent blood from flowing backwards. When the heart contracts, all of the blood in the left ventricle should flow out into the body, but if a dog or a person has a faulty mitral valve, a small amount of blood will fl ow backward from the left ventricle into the left atrium, resulting in a heart murmur.

As the disease progresses, the patient will develop other symptoms, including a cough, lethargy, high blood pressure, fainting, and eventually heart failure. There’s no cure for mitral valve disease. Veterinarians use medications to manage the heart failure and improve the dog’s quality of life for as long as possible. But dogs and their families will soon have a life-saving choice.

Orton, professor of cardiology and cardiothoracic surgery, has spent six years developing a minimally invasive treatment for mitral valve disease. Transcatheter mitral valve implantation, or TAMVI, uses a catheter to deliver an artificial valve through the apex of the heart.

An X-ray of an artificial mitral valve implanted via catheter through the apex of a canine heart
An X-ray of an artificial mitral valve implanted via catheter through the apex of a canine heart

 

“We have performed the procedure on a few dogs with short-term success,” said Orton. “This year, we are testing the second-generation valve and delivery device. If this works, it will offer a reliable treatment for a condition that is uniformly fatal in dogs.”

Orton is also working on a new drug therapy that will make it possible to prevent or slow mitral valve disease. His research group was the first to show that mitral valves produce serotonin locally, and that serotonin levels are elevated in dogs with mitral valve disease, indicating a potential drug therapy. By working on both drug therapy and valve replacement, his group is aiming both to prevent the disease and to help dogs with advanced heart disease that, until recently, faced certain death.

Originally Appeared In: Impact 2016, Sarah Ryan, 03-04-2016