Congestive Heart Failure in Dogs

Congestive heart failure is a broad medical term meaning that a dog’s heart cannot deliver sufficient blood to its body. This condition can be caused by a failure of the left side, the right side, or both sides of the heart.

When the heart starts to fail, the body can compensate to ensure that tissues receive the blood and oxygen they need. As the heart disease increases in severity, these compensatory mechanisms become overwhelmed. The heart is then unable to pump adequate quantities of blood, so fluid backs up in the body, causing congestion. With left-sided heart failure, fluid is retained in the lungs. With right-sided heart failure, fluid accumulates in the abdomen.

Congestive heart failure can occur at any time, but it happens most often in middle-aged to older dogs. Boxers, Doberman Pinschers, and Cocker spaniels may be genetically predisposed to certain types of heart failure.

What Causes Congestive Heart Failure?

While many conditions can lead to congestive heart failure in dogs, one of the most common causes is dilated cardiomyopathy. In this condition, the chambers of the heart become enlarged, which weakens the muscle walls so that they are unable to pump adequate amounts of blood to the body. As a result, fluid may back up into the lungs, making breathing difficult, or into the abdomen, giving the dog a pot-bellied appearance.

Other causes of congestive heart failure in dogs include:

• Heart valve deficiencies
• Defects in the heart walls
• Fluid in the sac surrounding the heart
• Heart rhythm abnormalities
• Heartworm disease
• Increased blood pressure
• Endocarditis (an infection of the heart valves)
• Tumours
• Pregnancy

What Are the Signs of Congestive Heart Failure?

In the early stages of congestive heart failure, your dog may show no signs at all. As the disease progresses, signs may include:

• Coughing
• Difficult or rapid breathing
• Difficulty exercising
• Weakness or lethargy (tiredness)
• Fainting episodes
• Gray or blue gums
• Abdominal distention
• Collapse
• Sudden death

What Diagnostic Tests May Be Needed?

To determine the cause of congestive heart failure, your veterinarian may recommend a number of tests, such as:

• Blood tests, including heartworm tests
• Chest radiographs (or x-rays) to assess the heart, blood vessels, and lungs
• An electrocardiogram (ECG)
• An echocardiogram (an ultrasound exam to evaluate heart structure and function)
• Blood pressure tests

How Is Congestive Heart Failure Treated?

In some cases, such as congestive heart failure that is caused by heartworm disease, treatment of the underlying condition may resolve some or all of the heart problems. If the problem is caused by a congenital condition (a heart defect that the dog has had since birth), surgical repair may be an option. In most cases, however, the problem cannot be cured, but treatment can help improve the dog’s quality and length of life.

Dogs with severe congestive heart failure may require initial hospitalization and oxygen therapy. If there is fluid in the abdomen, it may need to be removed to make your pet more comfortable.

There are many medications that your veterinarian may recommend to help reduce fluid buildup, improve heart function, and/or normalize heart rhythms. Your veterinarian will discuss each medication and its potential side effects with you. A low-sodium diet may also be recommended to help minimize fluid accumulation.

Most dogs with congestive heart failure require medications for the remainder of their lives. Periodic blood tests, radiographs, and echocardiograms are often needed to monitor treatment success and disease progression.