Understanding Heart Disease: Do Pets and Humans Have Anything in Common?

As cardiovascular disease becomes increasingly common, the American Heart Association and other health organizations are ramping up their efforts to educate and motivate the public about the importance of heart-healthy foods, exercise and other ways to combat heart disease.

But what about our animal companions? Can parallels be drawn between human heart disease and feline and canine heart disease?

Veterinarians at Tufts University recently looked at this very issue while developing the new Cats’ Assessment Tool for Cardiac Health (CATCH) survey for veterinarians to use when seeing feline patients. The questionnaire prompts owners of cats with heart disease to assess a pet’s quality of life — and it was inspired by a similar quiz used with human heart-disease patients.

Vetstreet sat down with Dr. John D. Bonagura, DVM, DACVIM, a professor of veterinary clinical sciences at Ohio State University College of Veterinary Medicine and head of the cardiology and interventional medicine service at the university’s veterinary medical center, to look at just how similar — and how very different — heart disease is in human, feline and canine patients.

How Prevalent Is Heart Disease?

Humans: Heart disease is the No. 1 cause of death for Americans. The AHA’s 2012 update on heart disease reported that, in 2008, cardiovascular disease caused more than 30 percent of deaths in the United States.

Dogs and Cats: Although reliable mortality statistics are not available for adult felines or canines, heart disease is not the leading cause of death in either species. That said, cardiovascular problems are relatively common — at least 10 percent of dogs develop valvular heart disease, a percentage that doubles for dogs who are over the age of 9. When it comes to cats, tracking heart disease is tricky, since felines often show no symptoms of the disease.

What’s the Most Common Form of Acquired Heart Disease?

Humans: Coronary artery disease is the most prevalent kind of heart disease found in adults. The main type of CAD involves plaque buildup in the arteries (atherosclerosis) that are responsible for bringing blood to the heart. As the layers of plaque grow and harden, less blood flows to the heart.

Dogs and Cats: Coronary artery disease is not a concern for dogs and cats. “This is probably the greatest difference between humans and their pets,” says Dr. Bonagura, a founding member of the Cardiac Education Group, an organization that offers resources and recommendations for heart disease in cats and dogs.

Mitral valve disease and dilated cardiomyopathy (DCM) are the most common canine heart diseases. Mitral valve disease affects a valve on the left side of the heart. As the valve’s flap gets thicker, it doesn’t close properly, causing blood to back up into the left atrium instead of exiting the left ventricle. Older, small-breed dogs are more likely to develop mitral valve disease, with male dogs having slightly higher odds than females.

DCM, meanwhile, weakens the heart muscle, so that it pumps less strongly and regularly. This condition is more common in large-breed dogs, like Great Danes, and some Spaniel breeds.

Pericardial effusion, when fluid collects in the sac around the heart, is another common canine heart condition that most often afflicts elderly dogs.

Eventually, DCM, mitral valve disease and pericardial effusion can all lead to congestive heart failure, causing fluid to leak out into the lungs.

Cats, on the other hand, are prone to hypertrophic cardiomyopathy (HCM). The walls of the heart thicken, the muscle becomes less flexible and the heart pumps less blood. HCM is a genetic disease that affects both mixed-breed cats and such purebreeds as Maine Coons.

What Are the Symptoms of Heart Disease?

Humans: Symptoms vary depending on the disease, but patients with atherosclerosis often have chest pain and shallow breathing. And, of course, there’s the big wakeup call of a heart attack.

Dogs and Cats: Dogs typically show signs of lagging energy, trouble breathing or getting comfortable and a chronic cough, which may be low-pitched. They can also collapse or faint.

Cats may also get lethargic, sleeping more than usual. And if a blood clot is swept from the heart and travels down through the aorta, felines can suffer a painful, sudden paralysis in their hind legs.

For both species, you should pay attention to how hard or fast your dog or cat breathes while asleep, so that breathing patterns aren’t influenced by panting or purring.

How Do You Test for Heart Disease?

Humans: Doctors can choose from a variety of diagnostic testing, including blood tests, electrocardiograms and imaging tests, such as CT scans.

Dogs and Cats: The first line of defense is a common tool: the stethoscope. For dogs, Dr. Bonagura notes, “a stethoscope screening is the most effective way to identify congenital heart defects and acquired heart valve disease.” But it’s harder to detect heart muscle diseases with a stethoscope, so Dr. Bonagura says that an echocardiogram may be necessary.

Kitties present a tougher diagnosis. “In healthy cats, the stethoscope is still useful but less so because many cats have innocent heart murmurs,” Dr. Bonagura explains. “More importantly, some cats have cardiomyopathy but no murmur or heart sound abnormality.” In some situations, a blood test may help a vet decide whether to pursue an echocardiogram or another diagnostic exam.

Which Medications Effectively Treat Heart Disease?

Humans: Depending on the type of heart disease, doctors may prescribe a blood-pressure medication, a blood thinner or a cholesterol-lowering drug, among other choices. Patients often use beta blockers to induce the heart to beat more slowly, and angiotensin-converting enzyme (ACE) inhibitors to relax blood vessels.

Dogs and Cats: “Many of the drugs used in animals are ‘extra-label’ uses of human drugs,” Dr. Bonagura says. Treatments vary according to the animal and type of heart disease — but research on their effectiveness is still thin in some cases. Evidence indicates, however, that dogs with congestive heart failure respond well to a drug cocktail that includes a diuretic, an ACE inhibitor and a drug to improve heart muscle contractions.

Research on feline heart disease treatments is even scarcer. From his own survey of specialist cardiologists, Dr. Bonagura found that most of them prescribe a beta blocker for otherwise healthy cats with obstructive HCM. Cats with congestive heart failure usually take a diuretic and an ACE inhibitor. Since cats with heart disease have a high risk for blood clots, they may also be prescribed an anti-platelet drug.

Can a Healthy Diet Help Prevent Heart Disease?

Humans: Diet can have a big impact on heart health. Eating foods laden with saturated and trans fats can raise cholesterol and contribute to plaque buildup in the arteries, while whole grains can act to lower cholesterol and help prevent heart disease.

Dogs and Cats: A healthy diet does not significantly help dogs and cats avoid heart disease. But Dr. Bonagura stresses that you should always discuss your pet’s diet with your veterinarian if your dog or cat begins to take heart medication. A dog with congestive heart failure, for example, should eat reduced-sodium meals and treats.

Does Exercise Help Combat Heart Disease?

Humans: Definitely!

Dogs and Cats: The kinds of heart disease commonly found in cats and dogs can’t be avoided through exercise. But, as with people, regular exercise will improve overall health and help prevent obesity in pets.

Dr. Bonagura points out one tandem benefit, too: “Dogs help us in this regard because many people get more exercise simply because they care for a dog!”