When I was caring for my MIL last year she had a stroke during the night. My little Bree(yorkie) kept growling, which she never, did trying to get me to go to grandmas room. Then she and Willow laid with my MIL on the bed during her last day of life. They would get up on her lap when she was up but never on her bed. They always followed me around. But not that day.
There was a "House" episode based on this article. It was a really good one where the girl exhibited no outward symptoms of being ill, but the cat had curled up on her lap so she knew she was going to die. Maybe last season or the one before?
I read a story about this in Reader's Digest. The cat was living in a dementia ward of a nursing home, so the patients involved didn't really comprehend what the cat's presence might have meant. A lot of the loved ones said they felt very comforted. I think it's a sweet story