None of us want to think about our dogs having heart trouble. After all, they need healthy hearts to wag their tails, right?

But dogs can develop heart problems that lead to heart failure. While dogs don’t tend to have heart attacks like people do, other heart conditions which can lead to heart failure are relatively common in dogs.

Heart failure in dogs rarely just happens out of nowhere. Your dog may have signs of heart disease ahead of actual heart failure. Paying attention to those signs and taking good care of your dog’s heart health — with regular checkups and measures to promote cardiovascular function — play an important role in managing the risk factors. Here’s what pet parents need to know about heart disease and heart failure in dogs to help protect their health.

What Is Heart Failure in Dogs?

To better understand signs of heart failure in a dog, let’s take a moment to learn the difference between heart disease and heart failure.

“Heart disease encompasses many types of impaired heart function,” says Dr. Hanie Elfenbein, a veterinarian based in Chattanooga, Tennessee. “It may be diagnosed as a heart murmur during a routine physical exam or may be diagnosed because of a change in behavior such as exercise intolerance, lethargy, or collapse.” 

If unchecked, heart disease symptoms in dogs can lead to congestive heart failure, or CHF. 

“Congestive heart failure is when the muscles of the heart can no longer circulate blood adequately,” says Dr. Elfenbein. “Fluid (congestion) then builds up either in the lungs (left-sided heart failure) or in the abdomen (right-sided heart failure).”

The symptoms of congestive heart failure in dogs are more obvious than signs associated with heart disease. Labored or rapid breathing is the main outward sign of heart failure in dogs.

“CHF is diagnosed when a dog has trouble breathing,” explains Dr. Elfenbein. “It often requires a visit to an emergency veterinarian because it can happen suddenly and a dog’s distress can be severe.”

4 General Signs of Heart Problems in Dogs

It’s critical to keep in mind that “heart failure is the end stage of heart disease” in dogs, says Dr. Weihow Hseuh, assistant professor of cardiology at the Cornell University College of Veterinary Medicine. So learning to spot the signs of heart disease in dogs and getting them in for regular veterinary exams goes a long way toward slowing the progression from heart disease to heart failure.

Here are possible signs of heart problems in dogs to watch for:

Heart Murmur

Not all heart murmurs in dogs are equal. Many puppies have an “innocent” heart murmur, which is a very quiet murmur that goes away as the puppy matures. These murmurs aren’t related to actual heart disease. However, murmurs which are associated with a heart disease are called “pathologic” heart murmurs.

But other murmurs can signal trouble. Mitral valve disease (MVD) is a heart condition which commonly causes a pathologic heart murmur in dogs. MVD is often genetic. Dr. Hseuh says small breeds — especially King Charles Spaniels — tend to be more prone to MVD. Toy Poodles, Cocker Spaniels, Pomeranians, and Yorkshire Terriers are also susceptible, although MVD-related murmurs can show up in large breeds too.

Veterinarians are trained to detect heart murmurs during their routine physical exams, which is why Dr. Hseuh says regular veterinary checkups are vital.

Lethargy or Malaise

These are two of the easiest-to-miss symptoms, especially as dogs age, says Dr. Michael Aherne, a clinical professor of cardiology at the University of Florida College of Veterinary Medicine.

“These can be tough to see with some animals,” Dr. Aherne says. “We might think it’s just an old dog.”

But lethargy, malaise, or exercise intolerance can be a sign of canine dilated cardiomyopathy, or DCM. DCM is a condition in which the muscles of the heart become abnormally thin, and the chambers of the heart enlarge. A heart affected by DCM isn’t effective at pumping blood through the body.

While a little laziness isn’t necessarily a sign of trouble, Dr. Aherne says, an obvious disinterest in playing, walking, or a marked decrease in energy is a good reason to see the vet.

Coughing

Another symptom of developing heart trouble that can be easy to misinterpret is coughing. Dogs may cough when they have respiratory illnesses, like kennel cough, or because of irritation from pollen or dust.

But a persistent cough, or especially one that follows exercise or a period of excited activity, might be a sign of heart disease. Dogs with heart disease sometimes cough excessively at night, as well.

“We tend to see a cardiac cough with large breeds,” says Dr. Aherne. “Coughing is their tell.” He adds that a “soft, insidious cough,” more than a hacking cough, is more likely a sign of heart trouble than a sign of something else.

Fainting

Dr. Elfenbein explains that fainting (also known as syncope) can be a symptom of some types of heart disease in dogs. “This type of fainting happens if the heart skips enough beats that not enough blood reaches the brain. The heart starts beating again on its own and usually the dog recovers within a few seconds and acts like nothing happened,” she says. “Dogs with fainting should be seen by a veterinarian immediately and started on medications to regulate their heart beat. Some dogs with syncope require a pacemaker.”

4 Signs of Congestive Heart Failure in Dogs

Symptoms of congestive heart failure in dogs include those listed above, but there are also symptoms that signal that heart disease has likely progressed to CHF. They include:

Rapid Breathing 

As previously mentioned, the most obvious sign of heart failure in dogs is rapid breathing. “Seeing how fast they’re breathing when they’re at rest,” says Dr. Aherne, “is the most sensitive indicator we have.”

He says a dog should be breathing less than 35 or 40 times per minute at rest and might only be drawing 15 to 20 breaths per minute while sleeping. If your dog can’t seem to catch their breath after they’ve been inactive for several minutes, it’s time to call a vet.

​​Moist Cough

The cough of a dog with heart disease is usually soft and dry. If the dog has progressed to heart failure, they usually have fluid build-up within the lungs. You may notice that their cough now sounds moist. In some cases, they may cough up foamy fluid. Keep in mind that other conditions, like kennel cough, can sometimes cause a productive cough, as well.

Swollen Belly or Swelling in the Legs

Because CHF occurs when a dog’s heart can’t pump enough blood to the body, fluid might collect in a dog’s belly, causing it to swell. “This is known as ascites,” says Dr. Elfenbein. 

If you see a bloated belly in addition to more obvious signs like labored breathing, it’s important to have your dog evaluated by a veterinarian as soon as possible. You may also notice swelling (edema) in the dog’s legs, especially their hind legs.

Collapse and Fainting

We’ve established that dogs with certain heart conditions faint due to changes in how often their heart beats, such as skipped beats. However, dogs in heart failure usually faint and/or collapse because their heart, despite its best efforts, isn’t effective at pumping blood. As a result, the dog isn’t getting enough oxygenated blood to their brain. A dog collapsing or fainting due to heart failure will often have a bluish tint to their gums and tongue.

Dog Heart Failure Symptoms: Next Steps

The good news about heart disease in dogs is that with regular veterinary checkups, usually easy to spot before it progresses to heart failure. 

And while emergencies happen, they almost always happen when pet parents are not paying attention to the warning signs of heart disease and impending heart failure. 

“It’s pretty rare to be surprised by heart failure,” Dr. Hseuh says. “[It mostly happens] if you don’t go to the vet regularly.”

The surest signs of heart failure in dogs are labored, rapid breathing and edema in the limbs (especially the rear limbs) or belly. Ignoring these warning signs is dangerous. 

If you spot any of the signs mentioned above, call a vet immediately. Depending on the condition, your dog might get a prescription for medication, such as Vetmedin (pimobendam), which can help manage the symptom of congestive heart failure in dogs Your veterinarian may also recommend an ultrasound of the heart (echocardiogram) and/or a Holter monitor to keep track of the heart’s rhythm.

If your dog is diagnosed with heart disease or heart failure, regular veterinary follow ups will be important for maintaining your dog’s health and quality of life. But promoting your dog’s heart health isn’t something you need to wait for a diagnosis to do, especially if you have a breed of dog that is predisposed to cardiovascular stress. Ask your vet if your dog could benefit from a nutritional supplement designed to support their heart function. These come in a wide array of options, including chews, capsules, and liquids, so they’re easy to add to your dog’s daily diet, depending on their needs and preferences.