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  • Jennifer herne

Why do cats purr?


I have often wondered why cats purr, as a vet tech I have seen cats in many different situations, fear, anxiety and contentment. I haven't seen many cats purr when they are in fear or when they are mad, but I have heard sick cats, nursing cats, and content cats purring. It obviously has something to do with their throats but what else is involved? There have been many theories over the years and most experts say the purring begins in the brain.

A purr is defined as a rhythmic neural oscillator sending messages to the laryngeal muscles causing them to twitch at a rate of 25-150 vibrations per second. This causes a sudden separation of the vocal cords, during both inhalation and exhalation. Wow! It is easier to say "purr".

So, now that we know the scientific physiological reason for purring let's talk about the other reasons for purring. As a cat owner, I know that my cats purr because they are happy. Now I am applying human feelings onto my cat by saying they are happy. In the animal world, they do not get happy. They can be content or relaxed orfull, but happy...I don't know about that one. We will leave that discussion for another time.

Cats who purr cannot roar. Evolutionarily speaking scientists believe that the roar is essential for a lion, they use this to protect their pride. The structures surrounding the voice box of lions are not as stiff as the cats who can purr. A mountain lion or bobcat doesn't need to roar, they both have the purring option. Small cats or loners do not have to compete for food or territory as much as lions, so they aren't equipped to roar, but as some of you cat owners know, they have other means to let you know their territory; urine marking. We will also save that discussion for another time.

So, do you still wonder what makes a cat purr? People will smile when they're nervous, when they want something, and when they're happy, so perhaps the purr can also be an appeasing gesture, but this is purely speculation.

Healing powers of the purr. Yes I personally believe that cats have healing powers. This is a personal belief, I know that when I feel stressed and I pet the cat and hear her purring, I become relaxed. Purring is an auditory sound that I attribute to peacefulness and calmness. It could be right and it could be wrong, but it really doesn't matter how or why; we have pets to add enjoyment to our lives.

One last thing for you to contemplate, vibrations are used in medicine as a treatment to help wounds heal faster, these vibrations are used at a rate of 25 Hz frequency, a cat's purr is also 25 Hz frequency. Strange coincidence?

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