From the Annals of French History, by Matt Miller

From the Annals of French History:
France, 1400. Greyhound Challenges Man over Murder, Wins Duel
This story begins, as any good story does, with a boy and his dog. Well, a man and his dog. And sentence one is obviously ignoring the film "A Boy and His Dog," for not fitting the criteria of "a good story."
Specifically, it was the greyhound of M. de Montdidier. After his master was murdered (with his dog the only witness), the greyhound repeatedly attacked the Chevalier Maquer. The French king, no doubt troubled (as these monarchs so often were) by a nasty bout of syphilis, decided this constituted an accusation and arranged for a trial by combat. His Majesty disregarded the equally plausible solutions that the greyhound took offense at Maquer’s doublet or that the man regularly bathed in duck grease. Maquer chose a lance. The greyhound, having given careful consideration to his lack of opposable thumbs, opted for teeth.
When the fight commenced, the dog jumped Maquer and latched onto his throat. Maquer (presumably through complicated hand signals, as spoken language had yet to be introduced to France) indicated that he would confess if they pulled off the dog. The court concluded that this proved guilt, strangled Maquer, and (we assume) awarded the dog the man’s horse and arms as compensation.