I had to check to see what forum we're in: "Our Pets"
So, yes, My wife and I have brought a cat and a dog to the vet to get euthanized.
The dog, a Golden, was so hard to let go. But he was on his third bout of cancer (shoulder) and had a limp due to an old injury to the carpus of the opposite front leg. It was when I had a dream of him limping on a pulpy mess of a foot that I spoke to my wife about letting him go.
The cat was different. We had him for only about a month when got sick. Hi lungs were filling with fluid. I don't remember the details, but the prognosis was poor, so we agreed to it.
Today we have an old dog and cat. I don't think the dog will get through the summer. He's blind and deaf and had separation anxiety even before we adopted him from the rescue organization. As well, he's weak and sometimes struggles to breathe.
Meanwhile, the cat just seems to be wasting away. He had a seizure many years ago and has been on a med ever since. But now his appetite is so poor, we struggle just to get him to take his med.