Are those Rats purring?

Bruxing in rats is akin to purring in cats. It's their way of showing they are
happy or content (although they can also do it when scared or nervous, like
at the vet).

My boys have quite a repertoire of adorable bruxing sounds. I've studied
their bruxing intently and come to the conclusion that it occurs in a number
of ways and at several levels. It seems to involve the teeth and air in the
mouth in the following ways:

- intermittent teeth grinding/chattering
- interspersed with a break during which the tongue moves around in the mouth
and the mouth opens and closes while the head lifts up (like smacking their lips
after a particularly good treat)
- the fooffing sound with air puffed into their cheeks/nose
- the air pressure becomes so great the upper face puffs up and eye balls bulge
out and vibrate (truly creepy, but adorable)

My rats will happily grind and chatter teeth without much effort, but they often need
extra encouragement to reach the ecstatic heights of bugeyedness. To do this, I
sit at rat level with them and stare straight into their big dark eyes. Then I alternately speak soothingly to them and chatter my teeth at them. When they start to brux back I imitate exactly what they do... the teeth grinding, lip smacking, head raises, and fooffing sounds. Before long it becomes a contest in who can brux the loudest and they usually win by playing their trump card... they KNOW I can't do the eye bulging thing!!! :

...bruxing and bulging...bulging and bruxing