How about "Old Faithful"?

Old Faithful, we rode the range together
Old Faithful, in every kind of weather
When your roundup days are over
There'll be pastures white with clover
For you, old faithful pal of mine.

Hurry up old fellow, for the moon is yellow tonight
Hurry up old fellow, for the moon is mellow and bright,
There's a coyote howling at the moon above
So carry me back to the one I love
Hurry up old fellow, 'cause we gotta get home tonight.

Check out these two video links. The first one is called "My Old Pal, Pal O' Mine" by Bob Nolan, and is better heard than read because of the way the solo and chorus parts overlap.

http://www.bobnolan-sop.net/Video/My%20Old%20Pal/index.html

And this one, "Bronco Pal." Note that Nolan's voice is dubbed.

http://www.bobnolan-sop.net/Video/Bronco%20Pal/index.html

And if you want a humorous one, check out "This Old White Mule of Mine."