We had to have our oldest cat put down yesterday. Very sad in the Davis house at the moment. We got Peggy from the RSPCA in 1992 shortly after we moved into our first house, she was 18 months old when we got her so she had had a good life when she was put down. She was around 15 years old which is very old for a cat.
Apparently she was suffering from kidney failure that may have been cancer but we didn't feel it was fair to put her through lots of tests.
The girls took it quite badly and were very upset when they were told but we thought it was only fair to be honest with them and tell them the truth and then just help them to deal with it.