Understanding Cat Behavior, Cat Behavior

Why do cats purr?

Isabel Hartley

One of the sweetest things about having a cat as a pet is the soothing sound it makes when it purrs. This unique rumble has long interested both scientists and pet owners, and many studies have been done to find out how and why cats have this comfortable habit.

The sound of purring isn’t just a sign of happiness; it can happen when a mother cat is feeding her babies, when a cat is relaxing with its family, or even when the cat is feeling anxious or uncomfortable.

Scientific studies have shown that when a cat purrs, it is really making a series of regular, low-intensity muscular contractions in its voice box. Cats purr for a variety of reasons, some of which remain mysteries.

It is believed that purring serves as a method of communication and a way for cats to soothe themselves; however, it is most usually used as a sign of happiness. Purring may help alleviate pain and promote bone regeneration, according to some specialists who believe the vibrations it produces may even have medicinal qualities.

Each rumble is a gentle glimpse into the complex social and physiological world of cats. It shows an evolutionary adaptation that serves many purposes, such as helping kittens bond with their mother and dealing with stress and healing.

The Science of Purring

A specific pattern of muscle contractions and vocal cord vibrations, which serve as a form of communication and have distinct acoustic properties, are what cause a cat to purr.

Anatomical Mechanisms

Cats produce the characteristic purring sound through a combination of laryngeal and diaphragmatic muscle movements. The neural oscillator sends intermittent signals to the laryngeal muscles, which control the vocal folds, and the diaphragm muscles, which assist in breathing.

These signals result in a burst of muscle discharges that cause the vocal folds to separate when the cat breathes in and out, creating a continuous sound. The process is known as flow-induced self-sustained oscillation. This self-sustaining oscillation can occur during both inhalation and exhalation, which is unique to the purring of cats.

Purring as Communication

Purring is a form of communication that can serve multiple purposes. While often associated with positive emotions, such as contentment, it is also used as a self-soothing mechanism when the cat is stressed or in pain.

The low-frequency vocalizations may promote healing through vibration. In terms of social communication, purrs can signal a friendly intent to other cats or humans, playing a vital role in the bonding between kittens and their mother. Body language often accompanies purring to provide further context to the message being conveyed.

Acoustic Properties

The sound bursts that compose a cat’s purr fall into the range of low-frequency sounds, typically between 25 and 150 Hz. These lower-frequency sounds are not only audible but can also be felt as a deep, comforting vibration.

Purr-like sounds can resonate with fibrous tissues and may have therapeutic effects, according to research under the direction of people like Christian Herbst. The sound’s frequency and intensity can vary depending on each cat’s unique anatomy, including the size of the vocal chords and surrounding connective tissue.

Biological Functions and Benefits

Cats purr for reasons that extend beyond communication, as the act of purring is intertwined with several biological functions and benefits ranging from healing to social interaction.

Healing and Health Benefits

Bone Health:

Purring has been associated with improvements in bone density and the healing of bones. The frequency range of a cat’s purr, between 25 and 150 Hertz, is considered therapeutic and may promote bone growth and healing.

This is particularly significant as these vibrations can help maintain bone density and mitigate bone density loss, an aspect beneficial for both sedentary and active cats.

Healing Properties:

The low-energy vibrations produced by purring not only help in conserving energy but also have potential effects on bone healing. These purring-like sounds found across the animal kingdom may be part of a caretaking behavior that contributes to the overall body composition and body temperature regulation, aiding in recovery and health maintenance.

Behavioral and Social Aspects


Within the myriad of cat-like animals, the act of purring is a nuanced form of communication. Cats may purr when engaging in social behaviors such as grooming or interacting with their owners or other felines.

A cat behavior consultant might note that purring signals contentment, a request for attention, or even a tool to soothe themselves or others in stressful situations.

Caretaking Behavior:

Purring also plays a role in the behavior for cats, especially during nursing. The vibrations can be a comforting signal to kittens as they feed, serving a dual purpose of reinforcing bonds and promoting bone growth and overall well-being from an early age.