Why Do Cats Purr?

Anyone who has spent any time around cats has felt and heard the distinctive purring sound that most people associate with a happy and content feline. However, there's much more to this cat characteristic. It can signal that a cat is happy, be used as a self-calming mechanism and even have benefits to the owner. Find out the science behind this mysterious sound and learn what it means when your cat purrs.

Why Do Cats Purr?

Purring is something that only happens with domestic cats and some wild cats, and even then, not all cats will purr. Some cats may purr more than others or have different situations that cause them to purr. So what does it mean when a cat purrs? The answer is, it depends.

You're probably already familiar with cats purring when they are happy and content, and this is one of the most common times for a cat to purr. They may make this noise when you're petting them, when they are laying on you or when they are excited to see you after you come home from work.

However, research has shown that cats don't only purr when they are happy. Purring can also be a defense mechanism and a way for them to stay calm in stressful situations. For example, a cat may purr during an examination when they are at the vet. This doesn't necessarily mean that they are happy about this visit. Instead, the cat may be purring as a way to calm themselves down and ease their fears over the exam.

Purring can also help relieve pain as well as stress. Cats often purr during labour to maintain a relaxed state and help ease discomfort, and the purring sound also helps the kittens find their way to the mother cat after birth so they can nurse. Kittens are born without a sense of sight or hearing, but they can feel the vibrations from their mother's purring and use that to find her. Kittens will mimic these vibrations as a way to communicate with the mother and the other kittens as well. There has also been some evidence that the low frequency vibration of the purring can make it easier for cats to breathe and help them heal from injuries.

Yet another reason for a cat to purr is to get attention. Similar to how a baby cries when it is hungry or cold, cats may purr to signal to their owners that they need food or something else. The louder the cat purrs, the more noticeable it is to the owner and the more likely the cat will get what it wants more quickly.

If you find yourself wondering, "Why is my cat purring?" you may need to look at other behaviour and context clues to discern whether your cat is happy, stressed or in need of aid.

How Does a Cat Purr?

Now that you understand some of the reasons behind this feline behaviour, you may be wondering how cats actually make this sound. It's actually the cat's vocal cords that are responsible for purring. As your cat breathes, the air moves over the vocal cords and the purring sound happens. Researchers believe that the purring sound actually creates something akin to a muscle twitch, which is what causes the whole-body vibration associated with purring.

A feline purr vibrates at around 25 to 150 Hz and can vary by cat. An interesting fact is that if a cat can roar (such as tigers or lions) they can't purr, but a cat that can purr (like your domestic cat) can't roar. This is due to a bone that is inside the vocal cords. In bigger cats that roar, this bone is flexible, which allows for a deeper sound, but in domestic cats, the bone is hard, which means there can only be air vibrations instead of the full roar.

What Are the Benefits to Humans?

You already know that there are plenty of benefits to owning a cat, such as lower stress levels, but did you know that your cat's purring can actually help you as well? Feeling and hearing your cat purr can be comforting and help relieve stress and anxiety. The low frequency of the vibration is also associated with healing effects, including increasing bone density, which may carry over into humans.

Cat owners have also been shown to have a 40% lower risk of heart attack and lower blood pressure than non-cat owners after they have heard their cats purr and interacted with them.

There has also been some evidence that cats may be able to help "heal by association." This is the ability to calm, soothe and sympathetically heal illnesses in people just by being nearby, and many people have said they can ease their migraines just by lying down with their purring cat next to them.

Living and interacting with cats brings many benefits, from getting a laugh from their many antics to reaping the health-related perks of being a pet owner. Return the favour by doing everything you can to keep your cat in peak condition and health. For more tips on cat ownership, behaviour and care, check out our cat care archives.