When Heart Failure Occurs

Its usually progressive, and early signs are easily missed

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Any cat can experience heart failure, something owners may be unaware of until it’s an emergency. The symptoms can remain “hidden” because cats are stoic and can often appear normal, even when they are very ill.

Most cases of heart failure are chronic and progressive, which means the heart failure is an ongoing condition that worsens over time, just as in people. Acute—or sudden onset—episodes of heart failure do, however, happen in cats.

Symptoms of Heart Failure

Signs that point to acute heart failure include “elevated respiratory rate, increased respiratory effort, lethargy, and exercise intolerance,” explains Bruce Kornreich, DVM, PhD, board-certified veterinary cardiologist and Associate Director of the Feline Health Center at the Cornell University College of Veterinary Medicine.

A cat who is having difficulty breathing will often crouch, with her head extended straight out and elevated and elbows held out to the side. You may notice the cat’s sides heaving as she breathes. This is an emergency.

Usually, an affected cat will be lethargic and/or unable to maintain activity. As heart failure progresses, signs of decreased blood flow (cold extremities, pale gums, weak pulses) may be observed.


If your cat is having difficulty breathing, can’t walk or move her hind legs, or you otherwise suspect heart failure, she needs to be seen by a veterinarian immediately.

Once at the hospital, the staff will attempt to stabilize the cat with oxygen, diuretics to help remove excess fluid, and medications to improve the ability of the heart to contract and/or to dilate blood vessels. Once she’s stable, the veterinarian usually will begin diagnostic testing.

“Available diagnostics include echocardiography, electrocardiography, radiography, blood chemistry monitoring, and pulse oximetry to measure the oxygenation of the blood,” says Dr. Kornreich.

Echocardiography uses ultrasound waves to visualize the heart. The veterinarian can see the dimensions of the heart and its chamber walls, as well as how fast and effectively it is contracting. This technology can rule out the presence of blood clots in the heart, which are relatively common with the dilated atrial chambers that are often seen in feline heart disease.

Electrocardiography, or ECG/EKG, measures the electrical activity of the heart and can tell if the heart is beating at an inappropriate rate and if some chambers are contracting out of order (called arrhythmia).

Radiography (x-rays) can show the size of the heart relative to the rest of the body and allows the veterinarian to observe the lungs, blood vessels, and surrounding tissues in the chest cavity.

Bloodwork assesses the function of major organs and may indicate whether infections are present and how much oxygen is being carried in the blood.

These tests are stressful for the cat, especially if she is in respiratory and cardiac distress. In some cases, the cat may be sedated to keep her calm while diagnostic measures are performed, or they may be postponed until the cat is stabilized.

Cardiac Treatment

Not surprisingly, treatment varies with the type and severity of the cat’s heart disease. Medication to address the heart failure and prevent clot formation is most commonly required for the rest of the cat’s life. Heart-specific medications include:

-Diuretics (such as furosemide) to treat fluid retention/congestion

-Angiotensin converting enzyme (ACE) inhibitors, such as enalapril, to dilate blood vessels and address negative physiologic response to heart failure

-Clopidogrel (Plavix) and/or aspirin to prevent clot formation in the heart

-Pimobendan (common off label use; FDA-approved for dogs) to increase cardiac pumping ability and dilate blood vessels

-Beta blockers (less commonly used) to control fast heart rates and minimize excessive oxygen consumption by the heart.

Causes of Heart Failure

Chronic heart failure is often related to issues with the walls of the heart.

Hypertrophic cardiomyopathy, a primary disease of the heart muscle in which the walls of the heart thicken over time, is the most common heart disease in cats. It limits the amount of blood that can enter the ventricles during relaxation, decreasing overall cardiac output and the amount of oxygenated blood that is pumped to the rest of the body.

Restrictive cardiomyopathy refers to a condition in which the walls of the ventricle become inelastic and blood flow into them during ventricular relaxation is restricted. This predisposes the heart to abnormalities of ventricular filling, with resulting poor output and, ultimately, congestive heart failure.

Dilated cardiomyopathy is a condition in which the ventricular walls become thin and less able to contract, resulting in dilation of the heart, poor cardiac output, and ultimately congestive heart failure. It is not nearly as common as it was a few decades ago due to the appropriate addition of the amino acid taurine to cat foods.

Heart Defects

Other structural abnormalities within or outside the heart can impact its ability to transport blood. Problems with valves can either restrict blood flow or allow it to regurgitate in the wrong direction, predisposing to congestion and, in many cases, congestive heart failure.

Congenital heart defects can result in abnormal shunting of blood from the oxygenated part of the system to the side with relatively low oxygen, resulting in decreased oxygen delivery to the body. Excess fluid outside the heart, either in the pericardial sac that surrounds the heart (called pericardial effusion) or in or around the lungs, can also impair cardiac function and result in decreased delivery of oxygenated blood to the body.

Monitoring for Heart Disease

To watch for signs of early heart failure, Dr. Kornreich recommends you:

-Regularly visit the veterinarian (annually until age 10; then twice a year)

-Feed a nutritionally complete and balanced diet

-Maintain healthy weight

Some cat breeds, such as Ragdolls and Maine Coons for hypertrophic cardiomyopathy, can have genetic tests to screen for heritable heart conditions.

The most important thing is to be aware of your cat’s normal status, so that if you notice she no longer plays or seems to have suddenly become finicky, you can get veterinary help immediately.

What You Should Do: Learn the signs of heart failure

Learn the signs of heart failure

Early Symptoms

-Increased respiratory rate (over 40 breaths per minute)


-Exercise intolerance

-Weight loss

-Decreased appetite

Emergency Symptoms

-Severely increased respiratory rate/effort

-Paralysis (most commonly hind limbs) due to a clot

-Open-mouthed breathing

-Weakness, lethargy