We have no idea what could have caused her to be ill either. Nothing has changed. She hasn't gotten into anything at the house (she's never been a forager or a chewer of stuff lying around), her diet hasn't changed, she's been eating the same brand of dog food and treats since birth (Blue Buffalo), she's an inside dog, when we take her outside it's on a leash and she stays in our unfenced yard, she hasn't been around any other animals.... so I have no idea. She's been in excellent health until now.