My sister had to recently put her favorite cat to sleep. It had bone cancer and its bones kept breaking in its legs. The vet didn't see that its bones where degrading till its last visit, that time he saw several holes in the bones and said it would cost way to much to try and save its life. First we all including the vet thought it had jumped from a spot way to high because its front legs where fractured and it couldnt walk. But time went on and it didn't get better, we kept giving him pain meds like baby asprin to help... Was cute at first because he would sit up straight and hold his front legs up like he was begging... But yea... He just got to the point where he couldn't even get up.