Looking at a cat who is contentedly and curiously engaged in playing with a toy is undoubtedly a peaceful experience. If you hear some guttural sounds coming out of your transfixed furry pal, however, you're not imagining things. Cats produce a lot of different noises when they're happy or deeply fixated on something.
The Classic Purr
The guttural sound you're hearing courtesy of your cat might actually be a classic purr. These deep, low and husky noises often denote cats who are having the times of their lives. If your cat is reveling in the enjoyment of chasing after his trusty stuffed mouse, he might not be able to help but purr. Purring in most cases signifies a pleased cat. On rarer occasions, it can denote a cat who feels unwell and is trying to calm himself, however.
Extremely deep guttural noises that emanate from the farthest reaches of a cat's throat can also indicate giddiness. If your cat is concentrating so intensely on playing that he's practically unaware of his surroundings, the raspy and throaty guttural sounds might just make a sudden appearance. Cats frequently make these guttural sounds when they're being petted, too. Temporarily hazy eyes sometimes accompany the sounds.
Growling is a deep guttural sound that is common in cats. Growling, in most cases, is a sign of a cat who is irritated and ready to get fierce. That isn't true in all situations, though. Cats sometimes growl when they're in play mode, similarly to canines. If your cat, apart from growling, isn't displaying any other hints of truculent behavior while playing, he could simply be behaving in a normal playful manner. Some common signals of a mad or scared cat include spitting, extended gazing, widened pupils, a rounded back, hissing and a rapidly beating tail. If your cat has a feline play partner sharing the toy, his growling could indeed indicate annoyance rather than playfulness. If that's the case, it's probably a good time for the play session to end.
Grunting and Feline Dilemmas
If your cat has encountered a dilemma in his play session, he might react by making brief guttural grunting sounds. Perhaps he accidentally pushed his toy mouse behind the refrigerator and can't get it out, although he can still see it perfectly. While your cat's trying to figure out his next step, he might grunt a lot.