Who was Bumper, and what happened to him when Pete was admitted into the hospital?

Bumper was Pete's favorite pet cat that he had nursed back to health after finding it as a sick kitten years before. When Pete was admitted into the hospital after his stroke, Charlie accidentally ran Bumper over with her car while driving home from the hospital. When she heard the news, Mary immediately ran Bumper to the veterinarian and paid for a very expensive, experimental surgery. Miraculously, Bumper survived.