Why does my cat (almost) constantly purr while he's awake?
I've heard cats purr to show contentment (though humans who want that to be true may be imagining it). WebMD suggests they purr (1) to get our attention ("feed me!"); (2) when content ("petting time"); (3) when anxious ("oh no, the vet!"); and (4) for healing. These reasons seem to be somewhat acute; I would expect a cat to purr when in those situations, but not all the time.
My adult (~7 yo) male, indoor cat, adopted from a shelter about a year ago (and already neutered when he arrived), quietly purrs nearly non-stop when he's awake, enough that the shelter's medical-exam notes included a comment about being unable to hear his heart clearly due to the purring. He doesn't just do it when interacting with humans; sometimes he'll be across the room doing his own thing, yet if I listen closely, I can hear him purring.
Is my cat just very happy all the time or is there something else going on?
I don't consider this to be a "problem to be solved", as I enjoy the purring, but none of my other cats have done this so I'm wondering if there is any cause for concern.
He arrived at the shelter already neutered. We don't know when that happened. My guess would be not recently; his previous owners had him for four years and he was already an adult when they adopted him, so you'd think that either *they* got him that way or they would have done it fairly soon after adopting. But obviously we're guessing.
I have a shaded silver female persian and she never stops purring. Seriously. She purrs 24/7 and has since I brought her home when she was 10 weeks old. I find it soothing but also wondered if this was unusual. I have always had male cats so I thought the constant purring might be a female thing at first. My vet says she is extra happy. Who knows?
The language of purring
Cats also purr if they're injured, while giving birth - even when dying. British zoologist Desmond Morris has observed that purring is "a sign of friendship - either when the cat is contented with a friend or when it is in need of friendship - as with a cat in trouble. (1)
A cat's purr is a type of language, as is the meow. The meow tends to be a more intense expression than a purr. Although purring can also have emotion effect on cat owners. Purring doesn't always indicate a cat is content, it can mean a variety of things. (2) At the very least it is a way of displaying submissive as opposed to aggressive intention.
German ethologist and cat behaviourist Paul Leyhausen interpreted the purr as a signal that the animal is not posing a threat. (3)
Purring and attachment
Even if you're across the room, your cat is still communicating with you, and being affected by your presence, which is probably reassuring for him. An interesting test would be to film him while you're out of the house. It could be his way of maintaining a connection with you. It is theorized that kittens and mother cats use purring as a way of bonding and that this may be a form of communication used throughout a cat's life to facilitate bonding.
Kittens are able to purr from a few days after birth. They can purr while suckling from their mother which may communicate contentment or maintain contact with her. ... Mother cats may also purr while nursing kittens, perhaps >to maintain contact with their offspring. Or maybe it’s all down to the hypothalamus detecting a pleasurable sensation and helping to trigger purring. (3)
Possible emotional damage of rescue pets
Contrary to the prevailing view, there is evidence that emotional pain may induce greater suffering than physical pain. Studies have shown that emotional factors weigh more strongly in animals’ behavioral choices than physical pain. (4)
Although it has yet to be determined what the long term effects of psychological or emotional suffering can be; it is becoming more apparent that a history of emotional abuse or neglect may well have lasting effects on a pet's psychology.
Given you got him from the shelter, it might be a huge relief for your cat to have found you, and this could result in him being extra purry. He may well have an underlying insecurity, without knowing his history, he may have been happy with another owner and then suddenly removed, this is conjecture, but the fact he ended up homeless, means he's been uprooted. It would be hard to provide a definitive explanation as to why your cat purrs so much.
What we know for sure is that animals do suffer psychological and not just physical pain, and that emotional abuse and maltreatment may be far more widespread and pernicious than physical abuse. (5)
The many articles I've linked discuss the variable nature of purring. If your cat is in good physical health and as settled as he sounds, it doesn't sound like something to be concerned about.
As for something else going on in terms of physical health, there is some discussion about possible physical health issues that can cause (perceived) excessive purring. How much purring is too much purring?
(1) Myths Debunked: Cats Purr Whenever They're Happy THE FELINE BEHAVIOR SERIES Paul D. Pion DVM, DipACVIM (Cardiology) and Gina Spadafori VeterinaryPartner.com
(2) University of Sussex News Research reveals how cats purrfect the art of exploitation
CAT COMMUNICATION - BODY LANGUAGE 2002-2009, Sarah Hartwell
CAT COMMUNICATION - VOCAL LANGUAGE (CAT CHAT) Copyright 1995 - 2012 Sarah Hartwell
(3) CAT COMMUNICATION - THE ENIGMATIC PURR 2008-2013, Sarah Hartwell
humanesociety.org Cat Chat: Understanding Feline Language
(4) A world of hurts—is pain special? Franklin D. McMillan, DVM, DACVIM PDF
(5) Emotional Pain in Animals: An Invisible World of Hurt Recognizing the psychological effects of animal abuse by Jessica Pierce, Ph.D. in All Dogs Go to Heaven
(a) What is Feline Infectious Peritonitis (FIP)? dr-addie.com
(b) Understanding Feline Infectious Peritonitis Niels C. Pedersen, DVM, PhD PDF
Hmmm. That agrees with my interpretation, which was that a purr means "I welcome your company."
The FIP connection is interesting in retrospect. At the time I asked this question we didn't know, but a few years later the cat died of FIP, only showing symptoms in the last few months. (They also think he was a lot older than the shelter thought he was.)
@MonicaCellio that's so sad to hear. I know I tend to associate purring as a positive thing.