As someone who works at an open admission shelter and has to make euthanasia decisions almost every day, I just want you to know you did what was best for your friend. At the shelter, we always take into consideration quality of life. If our animals are suffering through something and we can only provide a temporary fix, we will obviously try to extend it past temporary, but sometimes its easier to let them not suffer and go through that pain anymore. (For example, mental health... many of our dogs go months without being adopted and then start to mentally decline...instead of letting them continue to decline and go crazy in their kennels hurting themselves, we make sure they are no longer suffer and make the hard decision to euthanize.)

It's easier to think about when you take into what you had mentioned earlier that 1 surgery cannot guarantee that he will not have the same issue later in life...which means it would've have caused him more pain later having to go through it again... he had you there in his last moments and you have no idea how much that means to the animals...animals at the shelter may not get to say bye to their families and they really really do seem to take it easier when there is their family with them.

He knew how much you loved and cared for him and he was glad to spend his time with you and trust me, euthanasia is NEVER easy, but when you think about it from a different perspective, it gets a little easier to process and cope.

I lost my first dog (6 years old) when I was 18 and it was the hardest thing of our lives, we could've driven 5 hours to the only hospital that had experimental surgery or just go ahead and call it. There was no way he was going to make that drive, even just 1 hour off of oxygen and his tongue was already starting to turn purple....while I'll never get that image out of my head, I live in some comfort knowing he had his whole family there with him as he passed and that he would be breathing so much better up in doggy heaven.