A shepherd had a special favorite among the dogs who guarded his sheep. This dog, however, would snatch lambs to eat, and even the occasional sheep.
The shepherd eventually discovered this dog was the culprit, so he seized the dog and planned to execute him.
"But wolves do far more damage than I," the dog whined. "The wolves are your worst enemies. Why punish me? "
"It's the business of wolves to kill the sheep, but you are supposed to be their guardian," he replied. "A wolf is a predator, but you, wretched dog, are worse, for you are a traitor!"
Inspired by: Fables of Aesop and Other Eminent Mythologists by Roger L'Estrange, 330.
Notes: This fable is not part of the classical Aesop tradition; find out more here.
Here is an illustration from a 19th-century Aesop: