Impulse is equal to the change in momentum of an object. The momentum of an object is equal to its mass times its velocity.
The initial momentum of the dog is 80kg * 2m/s = 160kg*m/s.
The final momentum of the dog is 80kg * 3m/s = 240kg*m/s.
The change in momentum of the dog is 240kgm/s - 160kgm/s = 80kg*m/s.
Therefore, the impulse on the dog is 80kg*m/s.