It's probably Moose. He's transgender, meaning if you're a male and mate with him he'll have kits. If not, no idea :]
Viewing post in West Woods: Over Borders comments
there seem to be a lot of bugs regarding mating with moose. if you pay attention to his dialogue it sounds like he went through the cat version of surgery or something to become biologically male, but that makes no sense with the mating responses. frankly it makes no sense either way, since I've mated with him as a female and he's the one who has the kits, meaning whichever gender you are you will be able to have kits with him and he will be the one to get pregnant. maybe there's something I'm missing, or maybe mossy just hasn't tested mating with moose much.
I mean, there is a surgery (at least with humans) that could make him biologically male, but are you saying he hasn't gotten it? Either way, the kitting mechanics, specifically dialogue, are very out of whack. To be fair, I've had kits with Nightlight as a female and she also says that she's pregnant, so assuming Moose hasn't had surgery, it may just be a bug with that sort of relationship (excluding Breezestar).