1939 UK pet massacre: 750,000 killed amid WWII food shortages. NARPAC's pamphlet advised moving pets to the countryside or using a humane captive bolt pistol for destruction if care wasn't possible.
A source: https://en.wikipedia.org/wiki/British_pet_massacre
Oof. Thinking about needing to put my dog down myself is a heavy thought...
"Destruction" of a pet/animal somehow sounds more violent/less humane than just saying it how it is, which is saying a lot.