The Bloon Dog is a special agent in the next Bloons Tower Defense game, and costs $100. After being placed, it runs up to a bloon, grabs it, and buries it at its spot. It does this over and over again throughout the game, and buried bloons count as having been destroyed. It doesn't take very long for it to get a bloon and bury it, but the amount of time depends on the type of bloon. It can't do anything to MOAB-class bloons or bosses. After you use the Bloon Dog in 50 games, it becomes the Bloon Dog Pro. The Bloon Dog Pro is faster than the Bloon Dog.