Yes, but look through the gallery and you'll see what the artist thinks of that name. Personally, I think "dracony" sounds weird, and "draconequus" is already occupied as you said, so perhaps we should go with something like "hippodrakon"? (Come to think of it, that has a weird ring of "hippopotamus" to it..."dracohippos"?)
Rarity has put on a lot of baby fat, which gives her a somewhat filly-like appearance. She'll probably look like her old self about six months after the baby is born. Chasing a little kirin around is going to burn the calories faster than any workout program.