Why do cats purr: a curious sound of obscure origin

It is usually taken for granted that purring is a sound associated with animal satisfaction, but the truth is that cats can also purr out of pain and for other reasons. Thus, the meaning of the purr is not obvious without context. As for the physical mechanism that allows a cat to purr, all we have at the moment are theories.

What is really clear is that the purring of cats gives us great pleasure. So much so that purring has been credited with therapeutic effects and various health benefits. We will tell you why cats purr, according to the most common hypotheses, and many other curious details about this very peculiar sound.

Main theories

To understand why cats purr, we first need to talk about how this curious sound is made.

The difficulty in explaining the physical mechanism of purring is that there is nothing in the anatomy of a cat that resembles a “purring organ,” if you can call it that.

It is not entirely clear how cats make a purring sound. There is not a single part of the cat's body that is clearly intended for purring.

The most common hypotheses about where and how cats purr occurs are two:

• Cats can purr using their laryngeal muscles. With very fast movements of these muscles (20 to 30 times per second), the feline expands and contracts the glottis, which, combined with the inhalation and exhalation of air, creates a constant vibration. This is the most widely accepted hypothesis.

• The second theory indicates that the purr originates in the posterior vena cava, at the level of the diaphragm. At this point, the muscles compress the bloodstream, causing continuous vibrations that are transmitted through the bronchi.

The purr of a domestic cat has a frequency of 25 to 40 Hz and is highly variable. The sound varies depending on the breed, age and weight of the cat, so we can say that no two purring sounds are the same. The cat always purrs with its mouth closed, and the sound can be heard at a distance of no more than 3 meters.

Cats can purr as early as a few days old and soon learn to modulate the sound depending on what they want to convey or what their mood is.

Do tigers and lions purr?

Purring is characteristic of felines, but not only of cats: lynxes, cougars, cheetahs and ocelots also purr.

In the case of large cats such as tigers and lions, there is little evidence, and researchers disagree: some say they make short purring sounds from time to time, while others argue that, in general, cats capable of roaring, purr can not.

In any case, the main difference between cats and the rest of the feline family is that our furry friends can purr on both inhale and exhale, while others can only purr on exhale.

By the way, although purring is very often associated with cats, it is not unique to them. There are other animals that purr: raccoons, rabbits, squirrels, etc.

Why cats purr: 6 most common reasons

As we mentioned at the beginning, we usually take it for granted that cats purr in pleasure to show that they are happy. And while cats certainly often purr when they feel satisfied, the truth is that they also purr when they are having a hard time (due to injury or stress) and when they want something.

Thus, it is believed that purring is a form of communication with one instinctive, and with the other, a voluntary part. Its meaning is complex and depends on the context.

Of course, cats purr with pleasure, but it is believed that they do it for many other reasons: from pain, anxiety, discomfort.

There are no definite answers to the question why a cat purrs. However, 6 of the most common reasons why they purr are usually suggested:

• The cat is relaxed and happy. The first reason is perhaps the most obvious and the first that usually comes to mind for all of us: in fact, cats purr when they feel at ease and relaxed. If your cat purrs when lying in the sun or when you pet him, this is a good sign, and you can interpret it as a mixture of “I feel good” and “keep doing this, please.”

• She is hungry (or wants something). Domestic cats also purr very often when they are hungry and think it's time to eat. Usually this purr is combined with an insistent meow, resulting in a sound reminiscent of a baby's cry. A cat may also purr, in this case very vigorously, to get attention or when it wants something else.

• She is stressed and trying to relax. Cats usually purr when they are stressed, even if they are alone. It is believed that this is a way to regulate their own anxiety, like when children suck their thumbs.

• Appeasement. Sometimes cats purr to each other after a fight and even purr to their owner after being scolded. This may be the cat's way of relaxing, showing that she is not a threat and does not want conflict.

• Discomfort. Cats purr in a low, monotone tone when they are uncomfortable in a situation. For example, perhaps we stare into the eyes of a cat or hold it in a way that she does not like. This purr is easily distinguished from that which is a product of pleasure, it is much louder and with an irregular rhythm.

• Taking care of yourself. Finally, cats usually purr when they are in pain. As we said, this can be a way to calm down, but some studies claim that the low frequencies of this type of purr have certain therapeutic effects: they can soothe pain and promote healing in the animal.

Cat Purring: 4 Human Health Benefits

Animals prolong our lives...literally.

Caring for, petting, and spending time with your dog or cat reduces stress, reduces the production of negative hormones in the body, helps you sleep, and even lowers your risk of a heart attack.

Animals in general provide clear benefits on both a physical and emotional level. Cat purring is even used in therapy to combat anxiety and depression.

And the purring of cats, in particular, brings important benefits on both a physical and emotional level. When we hear our cat's purr, we always feel great, mesmerized and at peace with ourselves. And it's not our imagination.

• Reduces anxiety. The basis of the benefits that cats purr gives us is a very effective relaxing agent. So much so that cats and their purrs are used in many therapies to combat stress and anxiety.

• Reduces muscle tension. Reducing anxiety entails reducing muscle tension, which can cause problems such as headaches, back pain, neck pain, and many other complications. A cat's purr can be just as effective as a good muscle relaxant.

• Reduces the risk of depression (and helps fight it if you feel it). With that being said, living with a cat, taking care of it, and often "listening" to its purr can be very helpful if you're depressed or have risk factors.

• It strengthens your bones. By far the most impressive of the benefits of purring cats. Did you know that the frequency with which cats purr is similar to the frequency of the waves of machines used to regenerate bones? Based on this, there are studies suggesting that purring cats can help improve bone health and joint mobility.