My father in law used to sing a similar song:

I'm the owner of a mule The bob tailed southern kind
He had springs in both hind feet And both his eyes were blind

Why dont you hitch him up? Why dont you make him go
But every time i turned around It's whoa mule whoa.

well it's Whoa, mule, whoa. Don't you hear him holler?
Tie a bow-knot in his tail or he'll jump through the collar.

Why don't you take him to the track? Why don't you let him go?
Every time I turn around, it's Whoa, mule, whoa.