• Congestive heart failure is a condition in which a cat’s heart cannot deliver sufficient blood to the body.
  • Hypertrophic cardiomyopathy (a thickening of the heart walls) is one of the more common causes of this condition in cats.
  • Signs include difficult or rapid breathing, weakness, lethargy (tiredness), and loss of appetite.
  • Diagnostics to determine the underlying cause may include blood tests, radiographs (or x-rays), and echocardiograms.
  • Treatment of the underlying cause may partially or completely reverse the heart problem, but in most cases, the condition cannot be cured.
  • Medications can help improve the cat’s quality of life and prolong survival.

What Is Congestive Heart Failure?

Congestive heart failureis a broad medical term that means that a cat’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 enough blood to the body, so fluid backs up, most often in the lungs, causing congestion.

Congestive heart failure can occur at any time, but it happens most often in middle-aged to older cats. Maine Coon cats 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 cats, one of the most common causes is hypertrophic cardiomyopathy. In this condition, the muscle walls of the heart become thickened, so they are unable to stretch and fill with adequate amounts of blood to pump to the body. As a result, fluid may back up into or surround the lungs, making breathing difficult. Fluid may also back up into the abdomen, but this is less common in cats than in dogs.

Other causes of congestive heart failure in cats include:

  • Hyperthyroidism (an excess of thyroid hormone)
  • High blood pressure
  • Heart valve deficiencies or blockages
  • Defects in the heart walls
  • Fluid in the sac surrounding the heart
  • Blood clots within the heart
  • Heart rhythm abnormalities
  • Heartworm disease (rare)
  • Tumors
  • Anemia (low numbers of red blood cells)
  • Pregnancy

What Are the Signs of This Condition?

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

  • Difficult or rapid breathing
  • Loss of appetite
  • Weakness or lethargy (tiredness)
  • Collapse
  • Sudden death

If your cat shows signs of open-mouth breathing or panting, gray or blue gums or tongue, or leg paralysis (due to blood clots), seek veterinary help immediately.

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 thyroid and 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 hyperthyroidism, 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 cat 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 cat’s quality and length of life.

Cats with severe congestive heart failure may require initial hospitalization and oxygen therapy. If there is fluid surrounding the lungs or in the sac surrounding the heart, it may need to be removed to improve breathing and help the heart pump more efficiently.

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 prevent fluid accumulation.

Most cats 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.