Why do Cats Purr?

Purring is one of the soft continuous sounds a cat makes, like a gentle hum, but how can you tell why your cat is purring? Cats purr for a number of reasons, including contentment, happiness, and even fear. It is one of the most common sounds that a cat makes and usually means they are in a good mood. However, there is often much more behind it as purring can have healing, communicative and appeasing properties. Most of the time a cat purring is a good thing but sometimes it can be a sign of distress. To help you understand your cat more we explain what purring is, why your cat may or may not purr, and look into the science behind it.

What is Purring?

Purring is the noise made by cats that sounds like a low, continuous vibrational tone while they are breathing. This is a voluntary behaviour a cat does while its mouth is closed as they inhale and exhale. Cats use their diaphragm to create this continuous purring noise. When a cat purrs there are noticeable vibrations within their body.

Why Does My Cat Purr?

Purring is mostly related to happiness and comfort, but it can also be an indication that something is wrong. When a cat purrs, it is a way to communicate and can indicate negative and positive emotions. All animals tell us how they feel through their sounds and body language, so it is just a matter of paying attention to decipher why a cat might purr.

• Cats might purr because they are happy and content: Often cats purr when they are content and feeling happy. When cats purr because they are happy, they will have a relaxed body language and their posture is typically loose. Cats are often happy when they have been fed, sunning themselves by a window, laying in a lap, or in a warm environment.
• Cats might purr when they are asking for something: Sometimes cats might purr to get attention or ask for something like food or to go outside. They use this on occasion to get something without having to use a louder meow. They might also purr to get you to pat or stroke them.
• Cats might purr to calm themselves: An upset or anxious cat might find that purring has a calming effect and can actually lower their stress levels. Just like singing or humming can calm humans down, purring can alleviate tension. The purring releases endorphins which are a natural pain reliever and help reduce anxiety.
• Cats might purr to bond: Kittens and mothers purr to bond with each other. Often mother cats purr when feeding their kittens as it helps stimulate milk production. Mother cats may also use the purring as a kind of lullaby or comforting tool which helps calm both the mother and kitten. Kittens purr to let their mothers know where they are or how they are feeling. In the same way as cats purr to bond with each other, it can also be a way for them to bond with their owner.
• Cats might purr to say hello: Cats may purr as a way of saying hello to a person or other cats. While it is not known exactly why they use this type of greeting, it may be a way of letting another cat know they are friendly and non-threatening.
• Cats might purr to heal themselves: Cats purring can have therapeutic benefits and sometimes cats will purr to heal themselves. Cats may purr when they are injured or in labour because it helps to ease pain and regulate breathing. A cat’s purr has a frequency of between 20 and 150 Hertz which is the rate at which current changes direction per second. The frequency of vibrations is known to assist in inflammation reduction and wound healing which explains why they might purr when sick or in pain.
• Cats might purr because they are stimulated: When cats are stimulated while playing a game or being stroked, they can tend to start purring. This type of purring might be accompanied by licking, drooling or kneading as a sign of happiness and contentment. If the cat becomes overstimulated, the purring may become more intense which is a sign that they may become aggressive. At this point it is a good idea to stop the game and create a calm environment.

Why Doesn’t My Cat Purr?

Most cats tend to purr sometimes, whether to show contentment or anxiety. However, while it is not that common, some cats do not purr. There are a myriad of reasons this may be the case, including:

• Personality and temperament. Each cat has their own personality, and some cats just don’t purr. Like humans, cats have different temperaments and some may be more verbal than others. A cat with a more reserved demeanour may not express themselves through loud purring.
• Lack of exposure to purring. Purring is a learned action which cats consciously and intentionally do. When kittens are born they learn to purr from watching their mother and siblings. If they are not exposed to this from an early age, they may never develop the purring habit.
• Health and medical issues. Some cats may be physically unable to purr due to vocal cord or respiratory system issues which result in them unable to produce a purring sound. If a cat suddenly stops purring, it could be a sign that it is injured or unwell. Cats can sometimes lose their voice similar to humans with laryngitis. Their swollen throat may cause them to temporarily lose their ability to purr or meow. On a more serious note, sometimes cats can develop benign polyps in the back of their mouth, stopping them from being able to purr. If your cat suddenly stops purring, it is a good idea to take it to the vet to find the cause.
• Old age. When cats age, they can sometimes stop purring or purr less frequently. This is usually because of the health conditions associated with old age like arthritis, swollen joints, diabetes and urinary tract problems which affect their mood and may cause chronic pain, inhibiting purring.

The Science Behind a Cat Purr

While there have been studies into the science behind a cat’s purr, there is still not a full understanding about how a cat creates the purring sound. There are some scientific theories though. These include:

• Active muscle contraction: Some scientific studies have suggested that when cats purr, signals are sent to the muscles of the voice box and diaphragm which makes the chest expand when breathing. It is these signals that stimulate the cat’s vocal folds to vibrate, resulting in the purring sound.
• Fibros pads on vocal cords: Recent studies say there are fibrous ‘pads’ on a cat’s vocal cords which add an extra layer of fatty tissue that causes them to vibrate and make the purring sound.

Is Cat Purring a Good Thing?

Most of the time, purring is a good thing. It is an indication of contentment and security felt by your cat. On rare occasions, it can be stress or anxiety related and they use purring to calm themselves down. If purring with bared teeth, or panting, this is stress related panting. Other times, if your cat is injured or in distress, it may be purring to help heal and soothe itself.

Purring Benefits for the Owners

A cat purring can have therapeutic effects for owners as well as felines. The frequency of a cat purring has been proven to help improve general wellbeing and even help with mental health and other ailments. Studies suggest that purring can help lower stress and blood pressure levels in humans, help with recovery time of infection and swelling, and even promote bone and tissue healing. Cat purring is so soothing it can help relieve anxiety and even reduce the chance of a heart attack.

Cats purr for a number of reasons from contentment and happiness to illness and anxiety. When a cat slinks up to you and starts purring, it is usually because they are happy. However it is important to observe other behaviours to identify if there are any health or pain issues associated with the purring. In this article we have explained why cats purr, why some don’t and benefits to cats and their owners of purring.