Professor Jaak Panksepp says that animals other than humans exhibit play sounds that resemble human laughs.
These include the panting sounds made by chimps and dogs when they play and chirping sounds observed in rats.
Totally. Mingus is very vocal when we play. Not only does he "play pant", he also "monkey talks" and throws head-fakes like a running back. Then he smiles.
He also sighs at me when he's bored or frustrated. I think I saw him roll his eyes at me once, too.
My dog freaks me out sometimes...