The poem is a bit longer than what is usually read on the show, but the portion often shared is:
Ode to a Dead Dog
by Garrison Keillor
Oh, my dog, my dog, where have you gone?
You were the best dog I ever had,
You followed me everywhere I went,
And you never complained about the bad.
You never said, "It's too cold for this,"
Or, "You're taking me to the vet again?"
You never complained about the fleas,
Or, "This food is just plain rotten!"
You slept at the foot of the bed
And you wagged your tail when I came home,
You brought me my slippers in the morning,
And never once did you ask for a bone.
You were the best dog I ever had.
Now you're gone, and I miss you so,
But I'll see you again, my faithful friend,
When I go to heaven, I'm sure you'll know.
This is just a snippet. You can find the full text of "Ode to a Dead Dog" online or in Garrison Keillor's collections of poetry.