We had to put Douglas to sleep. It turned out he didn't have Addison's, his very first X-Ray showed body parts in entirely the wrong locations. He wasn't in pain, but it was just a matter of time. The vet gave us the option of keeping him there over the weekend, doing exploratory surgery, and if it was inoperable just not bringing him out of it. We decided not to have the dog spend a weekend in the vet's office on an IV and then die in surgery, since it seemed really clear something was pushing his organs into the wrong spots. We made a mistake with our first dog Fred and kept him alive way too long while we kept hope alive.
So, it is sad. But it reminds me of a story: Dog Death With Dignity