[TOMT] Children's Fantasy Book with a Chimera

So there's this kid's book that has a girl and a chimera on the cover, and the girl has black hair done up in heidi braids, and I think her name's Bird or Byrd, and she's kind of hugging a chimera (Though I think it doesn't have the goat head) and it starts off with her helping a baby that has "Cat's Fever", and there's an evil King who has something called "The Black Tongue" and her and some other orphans are riding around in a dog sled for a while.