Purring. It’s a comforting sound that every cat owner loves to hear their kitty make. Best described as a low rumble, one can often hear a cat purring as its fur is gently stroked or the back of its ears are lovingly scratched.
One might think cats purr to show that they are happy and, indeed, cats do purr to show contentment. But purring has more than one function.
Cats also purr when they are in pain, be it from injuries or when giving birth, and even when they are dying.
Purring is one of the many sounds a cat makes, apart from the usual meowing, hissing, growling and yowling.
Not all members of the Felidae family can purr – as a general rule, big cats roar, small cats purr.
Bobcats, cheetahs, lynxes and of course, domestic cats, are capable of purring while tigers and lions cannot.
Cats purr by throbbing their larynx and diaphragm muscles, which creates a rhythm of vibrations.
Scientists have multiple theories on how a cat starts to purr.
Some say that it is started voluntarily by a cat’s nervous system, meaning they can control when they purr.
Others suggest that purrs are caused by endorphin release, which occurs when they are feeling pleased or pained. Cats purr when they are giving birth, perhaps as a means of comforting themselves.
Kittens purr when they are nursing to let their mother know they are in good health. It also has been noted that friendly cats purr when meeting new cats to show their lack of hostility.
Interestingly, purring might not be meant for communication as much as a means to self-medicate.
Veterinarians have noted that cats tend to recover from injuries faster than dogs, particularly bone injuries. This is particularly observable in the number of cats that have survived falling from great heights.
According to some studies, these cats may have a 90% survival rate in spite of their injuries.
In a 1990’s study at New York State University, scientists found that bone density increases when bones are exposed to low-level frequencies. A cat’s purr falls right in that category, at 25 Hertz to 150 Hertz.
Hence, it is likely that purring is part of a cat’s way of keeping healthy and to recover from injury. Healthy cats also purr when they are around injured cats, likely in an attempt to help with the healing.
It is possible this knowledge can be used to help humans too.
As an experiment, rats and turkeys were attached to plates that vibrated at the frequency of a cat’s purr. It was found afterwards that their bone strength had noticeably increased.
This discovery has led scientists to look into how this technology could be used for astronauts who risk bone density loss while living in space.
So, the next time a purring cat saunters up to you, just give them a good long cuddle and enjoy their affection.