This troper knows a woman who breeds German Shepherds. She told a story of when she bred one of her males to another person's female and put the two dogs in a pen to "do their thing", IfYouKnowWhatIMean. As she was leaving the pen, she accidentally stepped on a squeaky toy, which apparently upset the female, as she lunged at the breeder's face. The male, however, did a body-check on the female, knocking her to the ground before she could bite his owner and then standing between them while the woman left the pen. Once his owner was safe, he then started acting
the way you'd expect a male dog to when around a female in heat. The wisdom of breeding such a reactive female is questionable (I mean, she attacked because someone ''stepped on a squeaky toy''), but the male dog certainly counts.