A high-grade tracking-offensive ninjutsu where one calls upon ninken with a summoning, so they can tail the target from underground and assault it simultaneously with their fangs.
After the user marks an opponent with his or her blood, they roll out a scroll and smear their blood across it. Afterwards they place it between their hands and make the seals before slamming the scroll into the ground. The ninken are summoned there and travel through the ground following the scent of the blood. When the target is found, they erupt from the ground and hold down the opponent with their mouths.
In the English version, Kakashi mentioned the dogs can tear an opponent apart when Zabuza asked him if he planned to talk Zabuza to death and Kakashi replied he could do it "in a way" by giving the hounds the order. In the original, Kakashi simply told Zabuza to stop acting tough as they both knew he can't do anything while pinned down by the hounds.