It is a gut wrenching decision to make, but if the dog is suffering and no longer has a quality life it is the right deicision. I had to have two put down at the same time, one we raised from a puppy, he had been with us for over 15 years, the other one we acquired when he was about three years old, we had him about 11 years. It was almost like loosing one of the kids, but they were both old and sick, the vet helped by providing support and agreeing that it was the right decision. That helped, but it didn't make it any easier. We took it hard, said we would never have another dog, but acquired another puppy after about six months, and picked up a "pound hound" to keep him company. I sure hate the thought of the day I have to put them down, but at my age, I worry more about how they will be cared for should something happen to me.