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Heart Failure in Dogs


When it comes to heart disease, early or mild forms might not cause significant changes to your dog’s overall energy and quality of life. However, as heart disease progresses, it can cause clinical signs that are severe which may warrant a trip to the emergency room. 

For dogs with acute respiratory distress, heart failure is one of the most common diagnoses. In this article we discuss what it means if your dog is in heart failure. We also look at  some of the clinical signs, and what can you do to help keep your pup comfortable.  

What is heart failure in dogs? 

The heart is a muscle that is continuously pumping blood throughout the body. Freshly oxygenated blood is pumped from the left side of the heart and moves to all parts of the body, delivering this oxygen. Then, blood moves back out of circulation and into the right side of the heart. Oxygen from the lungs is put back into blood, and the blood moves back to the left side of the heart, starting the process over again. 

Congestive heart failure refers to inadequate pumping of the heart, and it can affect one or both sides of the heart itself. Due to factors like muscle wall thickening, muscle wall weakness, arrhythmias, and leaking heart valves, the heart is not able to efficiently pump blood. 

Left sided congestive heart failure

Left-sided congestive heart failure (LS-CHF) is the most common type, and 80% of these cases are due to mitral valve insufficiency. This is the valve between the two chambers on the left side of the heart: the left atrium and the left ventricle. When the mitral valve wears down and becomes leaky, blood will back flow into the pulmonary blood vessels that oxygenate blood. As a result, fluid can build up in the lung tissue, causing pulmonary edema

Right sided congestive heart failure

Dogs with right-sided congestive heart failure (RS-CHF) might have heartworm disease or have a problem with their tricuspid valve, the valve that separates the right atrium from the right ventricle. Blood ends up flowing backward into systemic circulation, resulting in problems like ascites (fluid in the abdominal cavity) and peripheral edema (swelling of the limbs).

Dilated cardiomyopathy

Dilated cardiomyopathy (DCM) is another type of heart disease that can lead to heart failure. It involves enlargement of the heart and dilated chambers, resulting in insufficient pressures to pump blood to the rest of the body. According to veterinary cardiologists, there is an increase in the number of cases of DCM reported and a possible link between DCM and the use of grain-free diets. This possible link is currently under investigation by various veterinary cardiologists and the Food and Drug Administration.  

Signs and symptoms of heart failure in dogs 

  • Lethargy
  • Frequent coughing 
  • Trouble exercising/ may collapse after physical exertion 
  • Gasping for air  
  • Pale of blue coloured gums

symptoms of heart failure

Dogs with heart failure may seem more tired or lethargic than normal dogs. They tend to cough frequently, especially at nighttime, and they are less likely to enjoy regular exercise. Even with mild exertion, dogs with heart failure can collapse. Severe cases can present with signs of acute respiratory distress such as gasping for air and having pale or blue-colored gums. 

These signs should be especially concerning if your veterinarian has ever detected a heart murmur in your dog. A heart murmur is a “whooshing” sound that can be heard when the heart pumps. Instead of a nice crisp “lub dub” kind of sound, there will be a vibration afterward. With high grade heart murmurs, you may be able to feel the vibration simply by placing your hand on your dog’s chest. 

Diagnosing heart failure in dogs 

A thorough physical exam can reveal other changes besides a heart murmur. 

Right sided vs left sided congestive heart failure

Patients who suffer from right-sided CHF may have ascites, and so these dogs typically have round firm bellies. Patients with left-sided CHF may have pulmonary edema, and so your vet might hear abnormal lung sounds when listening through their stethoscope. 

Further testing  

Blood work is important to make sure that the internal organs are functioning well because their supply of well-oxygenated blood is compromised. Heartworm testing is key, especially when right-sided CHF is suspected. 

Blood pressure should be checked, and your vet may also recommend an electrocardiogram (ECG or EKG) to look for a heart arrhythmia. 

Imaging is also important when heart failure is suspected. X-rays can show the shape and size of the heart, and they can also reveal pulmonary edema. In some cases, the heart can be large enough to push on the trachea (the windpipe) and cause further breathing problems. For more detail inside of the heart’s chambers, an echocardiogram is necessary and can help determine if your dog is truly in heart failure.

Treatment for dogs with heart failure 

There is no cure for heart failure. The effects of heart failure are typically managed with a combination of medications. 


Pimobendan is one of the most common meds prescribed because it can dilate blood vessels, helping high blood pressure, and it can decrease the force of your dog’s heart contractions. 

Diuretics like furosemide can remove extra fluid in the body, and ACE inhibitors like enalapril and benazepril are prescribed to help relax the blood vessels so blood pressure decreases.

For dogs who are still coughing a lot, some veterinarians prescribe bronchodilator medications or cough suppressants. 


Lower sodium diets are best for canine heart failure patients, though this rule is not as strict as it is with human heart failure patients. There are also long term benefits to supplementing omega-3 fatty acids for heart health. 

Avoid steroids 

Steroids should be avoided in patients with heart failure because they can increase blood pressure and increase the risk of edema. 

Heart failure can be a gradual but serious illness in dogs

For some dogs, heart failure may not be diagnosed until they are in acute respiratory distress and needing to go to an emergency hospital. With immediate treatment, many of our furry friends can make it safely home, and have their condition managed with a combination of oral medications. 

happy dog

Early detection of heart failure via routine examinations with your veterinarian can significantly improve life expectancy and quality of life for your canine companion!

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