We Had a Cat

We had a cat, imagine that! She can fit in a small-sized hat.
Her family loves her. They feed her good food. The cat grows and grows. She grows some more. She grows so big that some people think she might be a pig. Of course, she's not a pig, but she keeps on growing. She likes to chase mice and birds, and she even chases a dog! The cat keeps growing until one day the family notices that she isn't really a cat at all. What will the family do?