Heart Failure in Cats: Everything You Need to Know

Heart failure is not the same as heart failure. Many people have heart defects without feeling any symptoms. Heart failure occurs when the heart for one reason or another is unable to do its job anymore.

Heart failure can be defined as backward failure when fluid accumulates in various parts of the body or as forward failure when normal blood pressure cannot be maintained.

Backward failure (also called congestive failure) is the more common form and usually leads to fluid in the lungs (pulmonary edema), less often to fluid in the chest cavity, outside the lungs (hydrothorax), fluid in the abdomen (ascites) or fluid in the pericardium (hydropericardium). Cats rarely or never have fluid retention (edema) in the extremities, which people with heart failure often get.


Impaired heart function means that the blood is not pumped away efficiently enough via the veins that go to the heart from the body’s organs. The pressure in the veins then increases and fluid from the blood vessels penetrates into the surrounding tissue (backward failure).

Poor cardiac function can also lead to a sufficient amount of blood not being pumped out of the heart at each contraction, to maintain a normal blood pressure to all parts of the body (forward failure).

The poor heart function can be due to many different types of heart disease, malformations, valve leakage, heart muscle diseases and arrhythmias, but the symptoms of failure are similar regardless of the cause. Read more about heart defects.

Usually it is the left side of the heart that fails, which causes fluid to accumulate in the lungs or chest cavity. If the right side is mainly affected, fluid accumulates mainly in the abdominal cavity and abdominal organs.


The most common symptom of heart failure is fluid in the lungs, so-called pulmonary edema, which makes it difficult for the patient to breathe. To compensate for the reduced oxygen uptake, the cat tries to breathe faster, perhaps with strong abdominal movements or in the worst case with an open mouth, stretched neck and blue tongue (cyanosis). If this condition cannot be lifted quickly, it leads to death by suffocation, which is extremely painful.

Heart failure can also cause fluid retention in other places. If fluid accumulates in a larger amount in the chest cavity, it also causes breathing problems. Fluid retention in the pericardium or abdomen is usually not so pronounced in cats with heart failure that they cause severe symptoms.

Cats can get circulatory shock with severely impaired general condition and low body temperature, often down 34-35 degrees, compared to the normal 38-39 degrees. Impaired heart function can cause fatigue and intolerance to exercise. Severe, chronic heart failure can also lead to weight loss. Sudden cardiac death occurs, probably due to severe disturbance of the heart rhythm (arrhythmia).

Cats usually do not cough from heart failure.

What can you do yourself?

To avoid buying an animal that already has heart disease, you as the buyer should request a certificate that the veterinarian has recently inspected the animal without detecting any signs of heart disease.

Since most heart diseases are not congenital but come later in life, it is good to ask the veterinarian to listen to the heart, preferably once a year, so that you discover if a wheezing sound or an abnormal rhythm has arisen that gives suspicion of heart disease.

If you know that your cat has heart disease, you must always pay attention to signs that may indicate heart failure. If your animal is already on cardiac medication, it is important to follow your veterinarian’s prescription. It is especially important to remember to provide diuretics as otherwise the cat may quickly fall back into failure. Try to avoid being overweight as it leads to increased workload for the heart and impaired breathing capacity.

When should a veterinarian be consulted?

A healthy cat does not breathe faster than 30 breaths / minute at rest. Faster respiratory rate may indicate pulmonary edema. In severe heart failure, marked shortness of breath can occur, which leads to the cat breathing with an open mouth and perhaps in the worst case, a blue-gray tint on the mucous membranes of the mouth.

Heart failure in cats can be more difficult to detect compared to dogs because the cat itself chooses how much it exercises.

A cat with heart failure can become quieter, have decreased appetite, faster breathing and even shortness of breath.

Cats with heart defects can get blood clots that usually settle in the back of the carotid artery (aorta), where it divides into the hind legs.

The plug means that the hind legs do not receive a normal blood supply, which usually causes severe pain, paralysis-like symptoms in the hind legs, cold hind paws and sometimes bluish pads. This condition is not synonymous with heart failure, but the stress caused by the pain often triggers simultaneous heart failure, which further complicates the situation.

Fainting, collapse and fatigue can also indicate heart disease.

If you notice symptoms that you fear indicate heart failure, you should seek medical attention as soon as possible, or at least consult a veterinarian or knowledgeable staff, and do not wait until after the weekend, or overnight.

This is especially important if breathing, consciousness or general condition are affected. The earlier treatment can be initiated, the less suffering for the animal and the greater the chance that one has time to lift the failure before it is too late.


An X-ray is required to safely diagnose pulmonary edema. Fluid in the chest cavity or abdominal cavity can be seen both on X-ray and with ultrasound. Fluid in the pericardium requires ultrasound for a definite diagnosis.

Some animals get extra beats (arrhythmias) in heart disease, and it can contribute to heart failure.

Often, but not always, one can hear an arrhythmia with a stethoscope. If the veterinarian suspects arrhythmia, an ECG is needed to confirm the suspicion and determine the type of arrhythmia present.

In the case of blood clots that obstruct the circulation to the hind legs, blood samples can be taken and an elevated level of lactic acid in the hind legs can be found, but many times the clinical symptoms are sufficient to make a diagnosis.

To assess the function of the heart itself, an ultrasound examination (echocardiography) is required, but this is often not necessary in the most acute stage, but is preferably done after a few days when the breathing has hopefully improved.

To find any diseases that trigger heart problems or impair heart function, further investigations may be necessary.


The treatment takes place mainly in the form of medication and is always adapted individually depending on the type and degree of heart disease that causes the problems.

A patient with heart failure requires continuous monitoring because the condition is life-threatening and can worsen suddenly.

If the problems are mild, treatment at home may suffice, but in the case of significant breathing problems, it is recommended that the cat be registered for care at an animal hospital or clinic.

In acute pulmonary edema, it is important to minimize stress. The cat should be kept quiet. Oxygen is often supplied in an incubator, oxygen cage or via a breathing mask or hose in the nose. A small dose of sedative medication can be helpful in reducing anxiety and stress.

The main purpose of treating pulmonary edema is to drive away fluid that has accumulated in the lungs.

This is done by injections with diuretic medication which for best effect is given intravenously, directly into the bloodstream, either as a drip or intermittently, usually every two hours depending on the results and needs. The effect of the treatment is evaluated continuously and depending on the result, the amount of medicine needed is determined.

If the patient has a severe arrhythmia that contributes to heart failure, it also needs to be treated urgently. Depending on the type and degree, there are different injections or tablets to choose from. Sometimes several different medications have to be tried one after the other or combined depending on the effect.

When the condition has improved and is assessed as stable, which usually takes two to three days, the pet owner may continue treatment with tablets at home. For optimal results, combinations of different medications are often needed and the treatment is almost always lifelong. Topical medications are usually diuretics as well as tablets that prevent blood clots.

Fluid in the abdomen is treated in the same way as pulmonary edema, but the condition is not as acute as it does not carry a risk of suffocation and treatment can often be started at home.

Fluid in the pericardium can in severe cases require that the fluid be drained by puncturing the pericardium.

Follow-up visits usually take place after a few weeks. Then the treatment result is evaluated and possibly the medication is adjusted. Thereafter, visits are usually made once or twice a year, provided that the condition is stable.

Unfortunately, most heart diseases tend to worsen over the years and if you get to a stage when medication can no longer provide a good quality of life, you may have to let the cat fall asleep to avoid suffering.

Once heart failure has occurred, one can usually hope for a good life with the help of medication for a few more years.

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