Learn to recognize any signs or symptoms that may indicate heart disease, or worse—congestive heart failure. Proper diagnosis and treatment of heart disease or other heart conditions can help keep your dog’s heart beating for many years to come

By Mindy Valcarcel
August 24, 2020
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That characteristic “lub-dub, lub-dub, lub-dub” of a heartbeat is a fundamental sound of life for all animals—and it’s one we all hope remains strong and steadfast for many years. But just like with us humans, it’s possible for our four-legged friends to fall victim to heart disease. 

The thought of heart disease affecting your dog can terrify any pet owner, but it’s important to keep tabs on your pup's heart health so that you are able to recognize any signs that may indicate heart disease, or worse—congestive heart failure—and get your pup the right kind of treatment for any heart conditions that he may be diagnosed with. Here’s what you need to know about heart disease in dogs, how to recognize the signs, and ways to help prevent heart disease so that your dog can live his best, happiest life for many years to come.  

What is Heart Disease & Heart Failure?

The heart is divided into different parts to pump blood throughout the body. The right side, made up of the right atrium and ventricle, directs blood to the lungs so that the blood cells can pick up oxygen, which is then delivered back to the heart. Then the left side, which contains the left atrium and ventricle, pumps the newly oxygenated blood throughout the rest of the body through the circulatory system.

Just like with heart disease in humans, when heart disease develops in a dog, their heart must adapt or change in order to continue to work efficiently and bring oxygen to the rest of the body. These changes typically occur slowly over time—often years—and cause enlargement of the heart. This timeframe is known as the preclinical form of heart disease, considered as such since dogs show no obvious outward signs of heart disease.

But over time, heart disease can progress to heart failure. This stage of the disease is called the clinical stage, because this is when dogs begin to exhibit signs of heart failure (including weakness or fainting after exercise, coughing or difficulty breathing, or fluid buildup). At the core, heart failure—including congestive heart failure—typically involves a back-up of blood in the lungs or other organs, which makes it difficult for the heart to do its job efficiently.

How Do Dogs Develop Heart Disease?

Although it’s possible for dogs to be born with heart disease, it most frequently develops as dogs get older, according to Sonya Gordon, DVM, DVSc, DACVIM (Cardiology), a professor of cardiology at the College of Veterinary Medicine and Biomedical Sciences at Texas A&M University. “The most common heart disease in dogs, representing 75 percent of all heart disease, is characterized by degeneration of the mitral valve (the valve between the left atrium and left ventricle),” Gordon says. According to Gordon, this degeneration leads to a leaky valve, which causes the dog’s heart chambers to enlarge. “It eventually can lead to heart failure in some dogs. It also causes a heart murmur that can be detected by your vet,” Gordon says. 

Is There a Certain Age When Dog Owners Should Become More Concerned About Heart Disease?

Gordon says that heart disease in general is rare in dogs less than 5 years of age and increases in frequency as dogs age. “But in some cases it can be earlier or even later in life,” she says. And as in so many diseases and conditions, you might wonder if heart disease is more prominent in certain dog breeds. Gordon says that some purebred dogs have higher risks for specific heart diseases, but in general all older dogs have a risk of developing heart disease.

What Are the Signs of Heart Disease in Dogs?

Heart disease in dogs often goes unrecognized for some time—even years. “The most common cause of heart disease is characterized by a long preclinical stage when the dog is asymptomatic,” Gordon says. That means the first stage of heart disease will likely go unnoticed by owners, but may be detected by your veterinarian. 

Gordon says to keep in mind that not all dogs with heart disease will go on to develop heart failure, but that there are many clinical signs of heart failure in dogs to watch out for, including:

  • Fast breathing (more than 30 breaths per minute) when he is at rest or sleeping. Here are Gordon’s tips for evaluating your pet’s breathing rate at home
  • Increased effort associated with breathing
  • Restless sleeping; moving around a lot and changing positions
  • Coughing or gagging
  • Weakness
  • Reduced ability to exercise
  • Collapse or fainting
  • Decreased appetite
  • Weight loss
  • Distended belly
  • Depressed attitude; quiet and not interactive

If your dog exhibits any of these signs, contact your veterinarian for an evaluation.

What Are the Treatment Options for Your Dog’s Heart Condition?

If heart disease or heart failure is diagnosed, your veterinarian will walk you through the therapeutic measures you can take. Gordon’s guidance: “The main treatment options include daily medication or in some cases multiple medications. For dogs with the most common cause of heart disease, in the preclinical stage, once the heart reaches a certain size, starting a medication called pimobendan can prolong the symptom-free stage and overall survival. If and when the clinical stage develops (heart failure), additional medications will be needed.” But again, it’s important to remember that not all dogs who have heart disease will progress to this stage. 

Catching heart disease early on can be life-saving. “If it is diagnosed in the preclinical stage it can be many years before heart failure develops, and in some cases heart failure will never develop,” Gordon says. “Veterinarians—and veterinary cardiologists in particular—can offer more specific information on the specific prognosis for individual pets.”

Is It Possible to Prevent Heart Disease from Affecting Your Dog?

Gordon says that most cases of heart disease in dogs are not preventable, at least not at this time. But knowing what signs to watch for will help you know when you may need to make an appointment with your veterinarian. Faster diagnosis can mean faster application of treatments, and there are medications that can help delay clinical signs of heart disease and make symptoms less severe.