One of the terms I was raised up with was when an animal's life ended (usually by my dad's 22) he would use the term "put down" meaning for their death. There for a while, I also used that term, but not anymore, and for this reason.
I have two sons, and when they were younger this was a term they also associated with the death of an animal. Then one day one of the cats jumped up on the table, and I told my youngest to put the cat down. He looked at me with the most horrified expression. No mom, I don't want the cat killed. It took me a moment to get what he was thinking, and I had to clarify, "Not put the cat down but put the cat down on the floor." lol