Put to sleep
We saw a greyhound today and Mike explained to us that many of the greyhounds you see as pets are rescue dogs. He said "when the dogs are done racing they kill them. I guess I should say they 'put them to sleep'".
I corrected him. Say "killed them" that's what it is. Saying "put to sleep" is just a way to soften it and make it so people can deal with it. I mean... it's not like that give them a martini and an Ambien.