In my mind, a purring cat means a content cat. I imagine myself in front of a blazing fireplace with my purring cat curled in my lap while I’m reading a good book. However, purring takes place in a variety of circumstances.

Why Do Cats Purr?

In the veterinary clinic, cats staying in the hospital or boarding may purr continuously for one of two reasons. They may purr because they are comfortable laying in the sunshine and happy to be alive. Some cats become so euphoric while purring that they will drool and knead all over their families. Purring also may be a result of self-soothing because they are anxious or in an unfamiliar situation. Mother cats purr to their suckling offspring, and the kittens learn to purr back. Submissive cats purr to their dominant counterparts to lessen the odds of an aggressive confrontation.

How Do Cats Purr?

How cats purr remained a mystery for many years but now is understood to be a collaborative effort between the laryngeal (voicebox) muscles and diaphragm with a regular pattern of electrical stimulation occurring 20 to 30 times a second! Each burst of muscle discharge causes the glottis to close and the development of a pressure that, when dissipated by glottal opening, generates sound. Cats can produce other vocalizations at the same time. Most cats purr at an average of 25 decibels, but Smokey, who’s won a world record for the loudest purr by a domestic cat, weighs in at an astonishing 92 decibels. That’s as loud as a hairdryer or a lawnmower! It is rare, but there are some cats that do not purr. Some of these cats are deaf or were not raised around other cats. For some, the reason is not known.

What Does it Mean if a Cat’s Purr Changes?

Changes in your cat’s purr or meow may mean your cat is ill. Conditions such as inflammation of the epiglottis, tracheal and laryngeal cancer and hyperthyroidism may all change the sound or frequency of your cat’s voice and purr. The sudden development of drooling in a cat who has never drooled before may also indicate illnesses such as liver or kidney failure, oral disease or poisoning. Don’t take a change in purring lightly, and call your veterinarian.