The lyrics to the song "My Buddy" could easily be tweaked slightly for a tribute to a 4-legged pal. Here's a rough approximation of the song's lyrics:

Nights are long since you went away.
I think about you all night and day,
My Buddy, My Buddy,
Nobody quite like you.

Miss your voice, the touch of your hand.
I long to know that you understand,
My Buddy, My Buddy,
Your buddy misses you.