I have looked and none of them are the same as the one my dad taught me but they are pretty close.

I once had a horse whose name was Napoleon, named on account of his bony parts,
Bought him from an old Bostonian,very well known in all these parts.
He was so thin you could see right through him. He had hair as fine as silk.
Hitched him to an old milk wagon. Taught him to stop when I hollered "Milk!"
Along came a dude in the finest livery, said that he would run me a race.
Sure as a sinner, I was comin' in the winner when the dude cried,"Milk!" and I lost that race!