I'm sorry for your loss. They say that a reason a dog's life is so short is because he lives it fully and gives all of his love and devotion to man. I know how difficult it is to lose such a dear friend.
In addition to the other references, like Rainbow Bridge, you may find this a touching sentiment as well:
http://popmodal.com/video/955/Carson--J ... s-Dog-Poem
"Beau"
by Jimmy Stewart
He never came to me when I would call
Unless I had a tennis ball,
Or he felt like it,
But mostly he didn't come at all.
When he was young
He never learned to heel
Or sit or stay,
He did things his way.
Discipline was not his bag
But when you were with him things sure didn't drag.
He'd dig up a rosebush just to spite me,
And when I'd grab him, he'd turn and bite me.
He bit lots of folks from day to day,
The delivery boy was his favorite prey.
The gas man wouldn't read our meter,
He said we owned a real man-eater.
He set the house on fire
But the story's long to tell.
Suffice it to say that he survived
And the house survived as well.
On the evening walks, and Gloria took him,
He was always first out the door.
The Old One and I brought up the rear
Because our bones were sore.
He would charge up the street with Mom hanging on,
What a beautiful pair they were!
And if it was still light and the tourists were out,
They created a bit of a stir.
But every once in a while, he would stop in his tracks
And with a frown on his face look around.
It was just to make sure that the Old One was there
And would follow him where he was bound.
We are early-to-bedders at our house--
I guess I'm the first to retire.
And as I'd leave the room he'd look at me
And get up from his place by the fire.
He knew where the tennis balls were upstairs,
And I'd give him one for a while.
He would push it under the bed with his nose
And I'd fish it out with a smile.
And before very long
He'd tire of the ball
And be asleep in his corner
In no time at all.
And there were nights when I'd feel him
Climb upon our bed
And lie between us,
And I'd pat his head.
And there were nights when I'd feel this stare
And I'd wake up and he'd be sitting there
And I reach out my hand and stroke his hair.
And sometimes I'd feel him sigh
and I think I know the reason why.
He would wake up at night
And he would have this fear
Of the dark, of life, of lots of things,
And he'd be glad to have me near.
And now he's dead.
And there are nights when I think I feel him
Climb upon our bed and lie between us,
And I pat his head.
And there are nights when I think
I feel that stare
And I reach out my hand to stroke his hair,
But he's not there.
Oh, how I wish that wasn't so,
I'll always love a dog named Beau.
But I never held that against her! 
