Yeah, it's not pleasant. Years ago, we had two ShihTzus. When the time came for the first one to go, we took it to the vet to be put down. An old dog doesn't go quickly & it's very distraughtful to watch the process, the whole time you're apologizing to him. When the second time came it was in January. I was anticipating the imminent coming so at least I had a hole already dug. We already knew we'd never take another dog to the vet for this, & my wife just wanted them to die at home.... at lot cheaper TOO. I had been working midnights & when I came home in the morning, the dog was having another seizure & just laying out in the middle of the kitchen floor. I've already been begging her to let me put him down, but she held off. It's a terrible decision. She gave in this time & she said her good byes.
On another note, someone I know put down his lab who was quite old. He already dug the hole & when the time came, the dog got in the hole on it's own, laid down & covered its head with his paws. Now THAT's distraughtful !