An old adage says owners start to look like their dogs after they spend a long time together. However true that may be, human and canine hearts have a lot in common when it comes to the way they work.

They differ in certain physical ways, of course. The vena cava, the largest vein in the body and the one that brings blood back to the heart to pick up fresh oxygen, lines up differently in dogs than in humans. Dogs also usually have more pulmonary veins, up to twice as many as our four, which carry blood from the lungs to the heart.

While our pulse rates stay steadier, usually between 60 resting and 100 when we’re active, a dog’s pulse can vary from 40 beats per minute when resting to 180 when excited, especially in small breeds. And like people, they can get “white-coat syndrome,” the nervousness most of us feel in a doctor’s office.

Congenital Diseases: Human and Canine Hearts

We share the same basic cardiac construction with dogs, cats and most mammals: Two atria that act as receiving chambers for blood from the veins, and two ventricles that pump blood out into the arteries. So, when hearts malfunction, they often break down in the same way.

When we are born with diseases, they are called congenital diseases. Both puppies and babies can have congenital heart diseases. For instance, the artery on the right side can crimp, restricting blood flow and building up pressure; a doctor will perform a balloon valvuloplasty, inserting and inflating a balloon in the artery opening up the crimp and getting more blood to the lungs. In a case of patent ductus arteriosus, part of the baby or puppy’s blood flow system in the womb fails to close after birth. Surgeons can insert an occluder with a plug on both sides to shut that opening between major blood vessels.

Dogs and people may both be born with atrial and ventricular septal defects, where the wall between the chambers of the heart doesn’t completely close. Surgeons fix those defects in people but do so less often in animals because dogs and cats often live normal lives in spite of that “hole in the heart.”

Acquired Diseases: Human and Canine Hearts

Doctors see mitral valve disease in both human and canine hearts. In humans, it’s called a mitral valve prolapse. In both cases, the valve doesn’t close properly with each heartbeat, allowing blood to leak back into the left atrium. (Middle-aged women get it most frequently among humans.)

In people, surgery can repair the valve; for dogs, surgery is not widely available, though hopefully it will be someday. In both dogs and people, initial treatment is with medications. The medication most effective in dogs, pimobendan, doesn’t have seem to have the same effect for people. Beta-blockers, so effective in treating heart disease in people, don’t seem to have the same benefits for dogs. Even when diseases are similar between species, medication solutions may not be.

Pets and people can also be prone to cardiomyopathy, a disease of the heart muscle that can lead to heart failure. It manifests itself as dilated cardiomyopathy in dogs and hypertrophic cardiomyopathy in cats, though humans get both types.

Where Pets Have Us Beat

Hypertension, which is a leading cause of heart disease in humans, is rarely seen in dogs and cats unless they have kidney disease or other systemic disease. Hypertension isn’t the heart’s fault, anyway: The problem is actually your vessels, which are so constricted that the heart has to work too hard.

And here’s the kicker for those of us who love donuts: We get hardening of the arteries, but dogs rarely do. The fattest dog you ever saw likely didn’t have atherosclerosis, because their bodies deal with cholesterol differently from ours: No matter what or how much they eat, they don’t build up plaque.

Charlotte Animal Referral and Emergency is the pet version of a human medical center, and it’s open 24 hours a day, 365 days a year. CARE offers every type of treatment, from emergency care to board-certified specialty work after a referral from your primary veterinarian. You can take a visual tour of the practice at

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