I have only had one dog besides my current one and we had him (a lab humane society mutt) for 13 wonderful years. We made the decision and the appointment and on the scheduled day, he was having a "good day". It was the hardest thing we have ever, ever done. My husband wanted to turn around and go back home since Homer was having a good day, but we knew if we did, Homer would be the one to suffer. He was in severe pain all the time from his arthritis and had gone off his food. He was covered in tumors, which we never had biopsied because of his age and condition, we knew he wouldnt have been a surgical candidate and if it was cancer, we didnt want to spread it any faster. Anyway, he trotted into the vet all happy and started towards the kennel. We were afraid we were making a terrible mistake, but this 100lb dog was down to 65lbs and we knew we had to do it. This was almost 10 years ago and I am crying again, but I know it was the right decision. Did I want to keep him around longer? Hell yeah, I wish he was still here. Is he is a better place? You better believe it. You will know when it is right. You may second guess yourself and continue to miss him for the rest of your life, but you do recover. 5 years later, we got our little Huey and cant imagine how we went 5 years without a dog due to the fear of losing another one.