It's an illness that is unpredictable, her white blood cells are attacking her red cells. She needs constant monitoring and checking at the vet.
She is a little sweetheart, so calm and placid, and always easy to get in at night. I open the door and call her, and she appears.
Heidi was a stray and brought into rescue with four kittens, so her history is unknown. I decided to keep her. She wouldn't have lasted long in the wild. Hopefully we can keep on top of this and she will have a few more years yet.