CANINE TRAGEDIAN. "I, myself," says Plutarch, "saw a dog at Rome, whose master had taught him many pretty tricks, and amongst others the following. He soaked a piece of bread in a certain drug, which was indeed somniferous, but which he would have had us believe was a deadly potion. The dog, as soon as he had swallowed it, affected to quake, tremble, and stagger, as if quite stupified. At length it fell down, seemed to breathe its'last, and became stretched out in all the stiffness of death, suffering any person to pull it about or turn it over, without indicating the least symptom of life. The master was now lavish in his endeavours to restore the poor creature to life; and after a short time, when it understood by a secret hint that its time for recovery was come, it began by little and little to revive, as if awaked from a dead sleep, slowly lifted up its head, and opening its eyes, gazed with a wild vacant stare on all around. In a few minutes it got upon its feet, shook itself as it were free from its enthralment, and recognizing its master, ran merrily up to him. The whole of this scene was performed so naturally, that all who were present (among whom was the Emperor Vespasian), were exceedingly delighted."
It goes without saying that you can't try this at home! But you may find this story in Sholto and Reuben Percy, The Percy Anecdotes: Original and Select. Vol. 9. London: J. Cumberland, 1826, pp. 14-15