How Do Cats Purr?

Purring is a fascinating and very common behaviour in cats. Everyone has a different theory about how and why cats purr. Until recently, however, no one knew exactly how the sound was produced.

For many years, scientists tried to figure out this mystery. There have been many theories developed but none were proven to be true. One leading theory was that purring is caused by the vibration and movement of blood in the major blood vessels in the chest cavity.

Recent studies now show that the purr is caused by very regular, rapid, alternating activation of the muscles of the larynx (the muscle and cartilage at the upper end of the trachea, containing the vocal cords) and the diaphragm (the partition of muscles and tendons between the chest cavity and the abdominal cavity). The brain controls this activation.

Purring doesn’t just occur in domestic cats. Many wild cats as well such as cheetahs, pumas, ocelots and tigers also have been known to purr.

Despite our new knowledge of how cats purr, people still don’t completely understand why they do it. Usually cats purr when they seem to be happy and contented. Cats often purr when their humans are nearby although we might not always be able to hear the sound. Domestic cats purr most often when humans approach, pet or speak to them. However, some cats continue to purr even while they are sick.

Although a content and purring cat is a wonderful joy, purring can cause some problems at times. For example, if a cat is purring when his veterinarian is trying to listen to his heart and lungs during an examination, the purr may drown out any other chest sounds. As a result, your veterinarian may have to do some unusual things when examining your cat, such as turning on the water faucet. In reality, he or she may simply be trying to distract your cat’s attention in an attempt to stop its purring.

The next time you sit and snuggle with your cat, enjoy the wonderful sounds of her purr and think about how and why she is making this relaxing sound.

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