Retired vet. Whenever someone brought in a perfectly healthy animal to be put to sleep, I always encouraged it to be done privately in their absence. If they agreed, I secretly sent the animal to some friends who run a rehoming centre. Still charged for the "euthanasia".
I finally understand that story of the dog who led his new owner to a shallow grave, causing the previous owner to be sent up for murder one.
Ironically, it was Texas, and the guy was in fact...euthanized.