Blowing sounds are due to vortices in the blood inside the heart or in the large blood vessels that exit the heart. The vortices give rise to a hissing or hissing car sound that can be perceived with a stethoscope.


Blowing sounds are detected when listening to the heart with a stethoscope. Blowing sounds can be different loud and are usually divided into 6 different degrees, where 1 is the lightest and 6 the loudest. Blowing sounds can be heard more clearly over certain areas of the chest, depending on where in the heart the blowing sound occurs, and also at different periods in the heart’s contraction cycle. 

So-called systolic wheezing sounds are most common, they are heard when the heart contracts and pushes the blood out of the carotid artery (aorta) and large pulmonary artery (pulmonary artery). So-called diastolic wheezing sounds are less common, they are heard when both chambers of the heart relax to replenish blood from the atria. 

Where on the chest and when in the heart cycle the wheezing sound can be heard can provide clues as to what is causing the wheezing sound, but a definite diagnosis can rarely be made without examining the heart with ultrasound.


Blowing sounds are most often due to some form of heart disease and should therefore be investigated further. They can be congenital and due to malformations of the heart or large vessels. They can also be acquired, ie they have arisen later in life.

Blowing sounds can be temporary (intermittent). Many wheezing sounds are heard more clearly when the heart beats faster and may be impossible to perceive when the heart rate drops.

There are a few individuals, usually young and / or well-trained, who have wheezing without being able to detect anything abnormal with ultrasound. Even pregnant cats can get temporary wheezing that disappears when the body has recovered from pregnancy. 

If ultrasound has ruled out heart disease, these wheezing sounds are called physiological, because the heart is normal and they are probably due to the heart pumping so powerfully that vortex formation occurs in the blood.

Other conditions, such as anemia, fever and elevated thyroid levels (hyperthyroidism) can cause temporary wheezing that is not due to primary heart failure. In these cases, the wheezing sound should disappear when the underlying disease is under control.

Not all heart disease gives rise to wheezing, so heart disease cannot be ruled out by listening with a stethoscope alone. Read more about heart defects .


Both animals and humans can have wheezing and heart defects without feeling sick, as the heart is still able to do its job. Blowing sounds in themselves do not give any symptoms, but are usually signs of a more or less serious heart disease which in turn can give symptoms.

If the heart disease worsens over time, heart failure can occur. This is because the diseased heart is no longer able to maintain a satisfactory blood circulation.

Heart defects can cause more or less serious arrhythmias (ie arrhythmias), ie electrical disturbances that cause extra beats and irregular heartbeat. If they are mild, nothing is noticed on the cat, but if they are severe, they can lead to weakness, collapse, fainting and sudden cardiac death.

Cats with an enlarged left atrium are at increased risk of developing blood clots that form in the enlarged atrium and are then passed on to the aorta where they clog blood vessels and obstruct the blood supply. The most common location for these clots is at the back of the aorta, which means that the blood does not get out into the hind legs. The hind paws become cold, the pads can become bluish, the cat finds it difficult to use its hind legs and usually has a lot of pain.

What can you do yourself?

Breeders should, of course, strive to use only healthy animals for breeding and to inspect kittens for sale. As a prospective buyer, you should make sure that the cat you intend to buy is inspected by a veterinarian, which includes that a veterinarian has listened to the heart with a stethoscope, and that you receive a certificate of the result of the inspection.

If you are going to buy a purebred cat, you should inform the relevant breed club about possible control programs for the heart disease hypertrophic cardiomyopathy (HCM), and how widespread the disease is in the breed, and check any test results for parent animals and their relatives. Results of such examinations are shown in the protocol given by the examining veterinarian to the owner of the examined cat.

Ask your veterinarian to listen to your cat’s heart at regular intervals to find out if a new wheezing sound has occurred.

Cats fed food that lacks the sufficient amino acid taurine are at increased risk of developing DCM. This disease is rare nowadays, after feed manufacturers started adding taurine to cat food.

You do not get heart defects from being overweight, but if the cat has heart defects, it is important to keep it slim because obesity entails extra work for the heart and results in poorer lung function.

When Should A Veterinarian Be Consulted?

Kittens or adult animals to be sold should be inspected by a veterinarian before sale. If a wheezing sound is detected, it should be further investigated with ultrasound to try to assess whether the wheezing sound is due to disease and if so, if it risks affecting quality of life and longevity.

Breed cats that are to be bred should be tested by specially approved veterinarians according to the ongoing control program regarding HCM according to recommendations from the current breed club.

Since most heart diseases are not congenital, but occur over time and then often cause wheezing, it is wise to have a veterinarian listen to the cat’s heart even if you do not suspect that your cat is heart sick. If wheezing is detected when listening to the heart, further investigation by a specialist is recommended. Based on the results of the investigation, the veterinarian will give advice and instructions.

If you know that your cat has a heart defect, you should see a veterinarian immediately if you notice signs that may indicate heart failure, such as difficulty breathing, fainting, bloating, pain and paralysis symptoms from the cat’s hind legs. It can be difficult to see that a cat has fluid in the lungs (pulmonary edema) because they often adjust their limited oxygen uptake by being more quiet. They also tend to have poorer appetites.


When investigating suspected heart defects, the veterinarian can, in addition to listening with a stethoscope (auscultate), also perform an ultrasound examination, ECG examination, X-ray and blood tests depending on the symptoms and type of disease.


Depending on the type and degree of illness and symptoms, treatment and return visits are prescribed for follow-up by a veterinarian. However, many animals with heart defects do not need to be treated if they are asymptomatic and the changes are mild.

Unfortunately, the disease often worsens over time, and medication then becomes relevant. If heart failure with pulmonary edema occurs, enrollment in an animal hospital for intensive care may be necessary. In intensive care, treatment can be given with, for example, oxygen, repeated doses of diuretic medication, treatment of arrhythmias and continuous evaluation of treatment results. Such care often lasts two to three days before the patient can go home. In severe cases, the expected results of treatment may not be forthcoming and you may have to kill the cat to avoid suffering.

When the initial treatment has had the intended effect, it is usually followed by lifelong treatment at home, often with several different medications. With the help of medication, many animals can have a good quality of life for a few more years, although heart disease can rarely be cured. For optimal results, it is very important that you as an animal owner carefully follow the veterinarian’s instructions on medication, care and return visits.


Molli Ze

Molli's mission is to help cat parents care for their fur babies, in the easiest way possible. To do this, we share a plethora of guides and unbiased reviews to help you get what you need. She hopes that through our site, she can make life a little easier, and perhaps more affordable, for cat parents by helping you dodge expensive mistakes and mishaps.

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