This is an incredible video of a Mal who is a wee bit tight in his dog to dog intros. It’s at 1/10th speed, but just watch it unfold and look at the other dog’s reaction!
The small brown dog knows what’s going to happen.
Too bad the humans are clueless.
Both handlers failed to register the escalating tension between the dogs. They failed to seize opportunities to turn the dogs away, or step between them. Handler error preceding the tightened lease is the real reason.