I feel your pain, losing a dog is unbelievably hard to deal with as the bond is so strong.
I went through this with my ex's dog a few years ago, the vet had him overnight & told us next day to enjoy the weekend with him as he didn't expect him to last more than that, when we saw this vet two weeks later he said that he instantly changed his diagnosis when the dog saw us but didn't tell us as he didn't want to get our hopes up, one minute he had an old dog who would barely walk & when we walked in he transformed into a puppy.
He was a great vet for not giving us false hope because we treasured those last two weeks more than anything, we used all of our remaining holiday time to spend those last days with him & my employer even gave me extra days off for compassionate leave.
Having to have him take the long sleep broke our hearts.
I said that i'd never have another dog but a week or two later I met my Poopie (in my avatar picture), at first he wouldn't let me near him but I took him for a walk & he wouldn't leave my side from then on.
Two weeks later my brother let me have him & we've been inseperable for about 5 yrs.
I never say never, never is too long but when Poopie does go i'll probably not have another dog until I retire & have the time to devote to him/her.
My heart goes out to you wrapped in a big hug
