The third episode of the first season of Stargate SG-1 featured the episode “Emancipation”. When the team first exists the gate, they hear dogs barking and later see a boy being chased, and later attacked by a series of dogs. The team rescues the boy form his attackers with a few shots of their guns into the air.
These dogs are all Belgian malinois. Malinois are commonly used in police, military, and protection work and a well trained malinois can easily be controlled in an “attack” scene like this. Add on their primal look, intelligence, and ability to look like a killer makes the malinois a great choice for any scene where someone is “attacked” or even as a protector.
It is suspected that some (or all?) of these dogs were also used in the Millenium episode “Beware of the Dogs”.
These dogs were trained by Bonnie and Ryan Judd and Andrew Simpson. I do not have word on who these dogs are but form the pictures they look like American-working lined dogs.