Very tough to look a pet in the eye and do that. I put one in a large paper feed bag once and took care of it in that manner, but it was no picnic. I only did it that way because we were dirt poor and couldn’t afford an alternative.
setter, PL2 had a bad experience going to a vet. I did not want anyone but me put our dog down. I took him out to the country, to a pretty place, my wife stayed home. I was careful, my dog never saw my gun, it was over quickly (and his head did not move, you were concerned about that), and I was relieved and glad it was me with him in the end.