We had to have our cat put to sleep !!!

Cindy	What's the matter, you look as if you've been crying ?
Betsy	I have, I've just come from the vet's.
Cindy	What happened ?
Betsy	We had to have our cat put to sleep. She had a tumor which was incurable.
Cindy	Oh dear ! I'm really sorry to hear that. How old was she ?
Betsy	She was 15, which is quite old for a cat. But she really was like one of the family. That's why we're all so upset.

Explanation :

If a sick or injured animal is put to sleep, it is painlessly killed by a vet.

Example :  I'm going take the dog down to the vet's and have her put to sleep.