Nast cartoon of democratic donkey, from "harper's weekly", january 19th 1870. Rearing donkey labelled "copperhead papers" kicks lion labelled "hon. E. M. Stanton". Caption: "a live jackass kicking a dead lion. And such a lion! and such a jackass!"
there's a possible scriptural allusion to ecclesiastes 9:4 -- "a living dog is better than a dead lion" (kjv). Date: 19 January 1870.