BEHAVIOR & TRAINING

How Do Cats Purr: Unraveling the Mystery of the Vibratory Wonder

kitten lying and purring
Stella Noble
Written by Stella Noble

How do cats purr? This tonal vibrating sound is a mysterious puzzle that many have tried to solve for quite some time. It is unbelievable how such a small animal possesses the ability to produce that magnitude of sound. The mystery can only be unraveled by looking at it from a wide scope.

But why do you need to understand the science behind a cat’s purr? Isn’t it enough to simply delight in the soothing feeling that the purring elicits? While it is easy to assume that cats only purr when they are contented or relaxed, this is just a scratch on the surface of the whole phenomenon. Purring can also be a sign that your cat is sick, or that he is trying to convey something. We have gathered all the available information on what goes on behind this adorable and enchanting feline sound so you can understand your feline friend better.

In this article, we will explain the science of a cat’s purr in detail and outline its importance to both you and your kitty. We will also let you know why excessive purring could signify a serious health issue. Are there cats that don’t purr? You will also find the answer to that question below.

Why Do Cats Purr?

man petting cat who purring

There is a lot more than meets the eye when it comes to a cat’s purr. Getting to know why your cat purrs would be a great step towards predicting his moods, satisfying his needs, and above all, living harmoniously with him. Below are some of the reasons why cats purr.

Reason #1: As a Means of Communication

Cats mainly communicate with their body language, but it doesn’t mean that they can’t communicate verbally. However, unlike humans whose speech has developed over the years, cats have to contend with the few sounds that they can produce—and the purring is one of them.

See Also: How Many Sounds Can a Cat Make

Did you know that cats can produce many different-sounding purrs? For example, if your cat is purring because he is hungry, he produces a purr that’s accompanied by whimpering noises that almost sound like that of a baby. This makes it hard for you to ignore them. The idea is to appeal to the parental instinct in you and draw your attention towards offering him food.

Cats also purr to communicate pain, boredom, illness, and other emotions. These are usually accompanied by other signs and indicators. Knowing how your feline looks and sounds when he is healthy will help you quickly realize when something is amiss.

See Also: How to Tell If Your Cat Is Sick

Reason #2: Bonding between a Mother and Her Kittens

cat communicating with her kittens

A nursing mother is known to purr in order to communicate with her kitties. She uses the purr as a lullaby. It acts as an audio stimulus that makes them settle down. It puts them to sleep the same way rocking or humming does to a human baby.

Kittens start purring a few days after birth. During this time, their auditory and visual faculties are not yet fully functional. They use this as a way of assuring the mother that they are okay. They also use purring to call out to their mother when they feel that she is absent.

Reason #3: A Display of Happiness and Contentment

happy cat purring

A cat purrs when he is happy and contented. This will be occasioned by a full tummy and sound health. He will also purr while eating his treats. Kittens also tend to purr when they are done nursing to show contentment. Tickling and massaging can also make cats purr softly with pleasure.

See Also: How to Massage a Cat

This display of happiness and contentment can make us, their owners, happier as well. Cat purrs fall under a frequency range that can relax our nerves and make us feel more at ease. It is scientifically proven that petting your cat and listening to the constant vibration of his purr has a calming effect on humans. Reduced stress consequently lowers blood pressure levels. This spells out better health for you.

Reason #4: To Ease Pain

cat easing human pain

Think cats only purr when they are happy and healthy? That’s not always the case. You shouldn’t let your guard down when it comes to your cat’s health because purring can also indicate that your cat is in pain. Purring can also indicate that your cat is trying to help ease your pain.

  • Cats tend to purr during labor. The purring triggers her brain into releasing endorphins. This hormone acts as a painkiller and helps her relax. Purring is also a better alternative to pained cries that would otherwise attract predators—especially if the cat is an outdoor or a feral one.
  • Also, cats can produce purrs that contain frequency ranges that can accelerate the healing of fractures and breaks. These frequencies also soothe sore muscles. The reason is that cats are known to be heavy sleepers—sometimes averaging 16 hours a day. These long spells of inactivity reduce their bone density and muscle strength. Cats counter this by purring. It can speed up your healing as well. The frequencies of the purrs have been said to be within the same range as the ones used in ultrasound machines to accelerate the healing of bone fractures in humans.
  • In addition, when you experience difficulties in breathing, try and breathe in sync with your cat’s purrs. They mimic the normal breathing dynamics of a human—thus helping you with a demonstration of what to do.

However, don’t try to mimic your cat’s purr. If you have tried it before, then you must have found it impossible. You probably experienced shortness of breath after the first few seconds of the futile attempt. This begs the question: how do cats do it?

The Science behind a Cat’s Purr

tabby cat lying on steps

Just like human beings, cats have many ways of making their presence known. These include sounds and body language. The sounds may include purrs, screams, caterwauls, hisses, chirps, and chatters among others.

What makes the purr stand out is the fact that it is present through the entire respiratory cycle—both inhalation and exhalation. The facts behind how this is possible are still shrouded in mystery, but several theories have been used to describe the science behind a cat’s purr. Here they are:

Theory #1: The Vibrating Vocal Cords

One theory suggests that the laryngeal muscles—whose work is to open and close the space between the vocal cords (glottis)—are the source of the purr. The muscles receive a repetitive signal from the neural oscillator in the cat’s brain—causing the muscles to tremble at 25 to 150 vibrations per second.

Rapid dilation and constriction of the glottis then cause a detachment of the vocal cords. The air exchanged during the inhalation and exhalation vibrates—resulting in the purr. This is the leading theory in explaining the phenomenon. It gets credence from the fact that cats with laryngeal paralysis cannot purr.

Theory #2: The Soft Palate

cat showing her palate

Another theory suggests that purring originates at the back of the throat. This area contains an elongated soft palate which houses skeletal muscle fibers. This theory proposes that cats can voluntarily vibrate their soft palate to make the purring sounds.

Theory #3: The Turbulent Blood

This theory suggests that purring is a sound made by the swirling of blood. The fluttering sound results from increased blood flow in the main artery (inferior vena cava). This artery has a constriction in the area near the cat’s diaphragm. The movement of blood through this constriction results in a rhythmic noise that is amplified by the diaphragm.

This sound is carried through the cat’s trachea and into the hollow cavities of the skull—resulting in purring. The hairs on a cheetah’s chest have been found to vibrate as it purrs—giving credibility to this theory. However, it loses traction when it comes to domestic cats whose chest hairs do not vibrate when they purr.

Theory #4: The Hyoid

gray cat purring

The hyoid apparatus is a series of small bones that support the larynx and holds the tongue in place. This theory suggests that purring occurs when the hyoid apparatus vibrates.

Theory #5: The False Vocal Cords

This theory sees purring as vibrations made when air moves over the false vocal folds. These are mucous membranes that are located in the voice box behind the true vocal cords.

Do All Cats Purr?

bobcat on the tree

Not all cats have the ability to purr. Cats that purr can’t roar while the ones that roar don’t purr. The difference is attributed to a bone called the hyoid found in the larynx. The hyoid is flexible and elastic in roaring cats. It stretches to increase the pitch of the cat’s roar.

You might wonder: does the same rule applies to big cats? Big cats roar, so is it safe to assume that they can’t purr?

The shape of a big cat’s vocal cords is different from that of a domestic cat. In big cats, they are flat and rectangular rather than the normal triangular shape. This reduces the lung pressure and allows the cats to produce very loud roars.

There is a reason for this kind of evolution; purring comes in handy for domestic cats that need constant communication with their kind and humans and hardly need to scare away competitors during feeding. Big cats, on the other hand, need the roar to keep competition at bay and mark their territory.

Surprisingly, however, some large cats like bobcats and cheetahs can purr. Nonetheless, despite having a flexible hyoid, the snow leopard cannot truly roar or purr. Instead, it produces a sound that is commonly referred to as “chuffing.”

Did you know that purring is not a sound that’s strictly limited to cats? Their relatives—such as mongooses and genets—also purr. Did you know that hyenas and guinea pigs do it too? Moreover, did you know that there’s actually something that’s known as “The Purring Disease?”

F.I.P: “The Purring Disease”

white and orange cat purring

As the name suggests, Feline Infectious Peritonitis (F.I.P) is an infectious disease that manifests itself by causing an inflammation of the stomach lining. The disease occurs when the cat’s immune system is unable to fight off the feline coronavirus infection.

The name ‘purring disease’ stems from the excessive purring made by infected felines. The ailment mostly affects young felines that aren’t one year old yet, as well as senior cats.

The intense form of F.I.P causes severe damages to blood vessels. They rupture and deposit fluids into the abdomen and the chest cavities. This is known as the Wet F.I.P. The abdomen swells up due to the accumulation of the fluids. The infected cat will also exhibit difficulty in breathing due to fluid buildup in the lungs.

Dry F.I.P is the most persistent form of this disease. It has no outward defined symptoms or signs. The infected feline experiences loss of appetite, has a dull coat, and yellow eyelids (jaundice).

An effective form of treatment for F.I.P. has yet to be found. In spite of this, it is essential that you take your cat to the vet if he shows any of the above signs or symptoms. This is because they could also signify other treatable health conditions.

Wrap Up

man petting orange cat

A cat’s purr is an amazing phenomenon. Apart from helping the cat in relaxation, its other functions include communication, bonding between a mother and her kittens, and healing.

Your feline friend’s purrs are great for you as well. They improve your overall health by reducing your stress and blood pressure levels, improving your breathing, healing your fractures, and soothing your muscles. Knowing that your cat benefits from his own purrs is definitely something but benefiting from them as well is purely amazing.

While scientists haven’t come to a unified conclusion yet about how cats purr, the theory that cat purrs are produced when the vocal cords expand and constrict rhythmically after receiving repetitive messages from neural tissues in the brain seems to make more sense than several others that don’t hold much water.

While it is normal for cats to purr, not all of them have this ability. Cats that roar don’t purr and vice versa. Generally, big cats roar while small ones purr. Some big cats that roar are bobcats and cheetahs while a snow leopard can neither purr nor roar.

Too much purring can be a sign of a health issue like the F.I.P—more commonly known as ‘the purring disease’—but it could also mean other things. F.I.P comes with other signs and symptoms. A visit to the pet can help put your mind at ease.

As usual, we delight in your feedback. Let us know how you feel about your cat’s ability to purr by leaving your comments below. Want to know more about how special of a creature your little friend is? Check this article out to learn how cats see the world.

About the author
Stella Noble
Stella Noble

Stella Noble lives in Warren, Michigan with her family and three cats. She is a Certified Cat Trainer and a member of the International Association of Animal Behavior Consultants.

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