The "Whoa, Mule, Whoa! posted by Mark Cohen 19 Mar 01, and this fragment in Perrow, seem to be related. They seem unrelated to the 'sleigh' song written by Hays (see link above).

WHOA, MULE!

Whoa, mule! whoa! Can't you hear him holler?
Tie a knot in the end of his tail, Or he'll jump through his collar.*

* "a stock gibe at an underfed animal. Cf. Jour American Folk-Lore, vol. xxiv, p. 371."
Mississippi Negroes, MS of A. B. Pitts. 1909. E. C. Perrow, "Songs and Rhymes from the South," II Songs in Which Animals Figure, 1911, Jour. American Folk-Lore, vol. 25, pp. 137-155.