The Achievement is located in the third Mission called "No Mans Land". "To Pounce" an Enemy with the Dog, hit the RT Button as Dog in the near of an Enemy.
Here are the 3 Areas where you control Riley:
- Directly at the beginning of the mission, is your first Dogkill. ( 1 / 10)
- Some time later you come to the Dogtutorial. Follow the Steps and you'll get 3 more kills. ( 4 / 10 )
- Some Minutes later you will cross a Tunnel, after the Tunnel is the last Dogarea. Here are many Enemies. Stay with Riley in the Grass and kill an opponent after another on the Way to the Missionmarker.
It is not really hard, nearly all Enemies stay alone. Just go up to them and hit the RT Button.
Here is my Video with all 3 Areas and the 10 Kills: