The Chechen's Rottweilers were a pack of vicious attack-dogs, owned by The Chechen.
During his meeting with The Scarecrow regarding one of one of his drugs ruining one of his customers, because the mob boss anticipated the inevitable arrival of Batman due to seeing the batsignal, the Chechen brought along his Rottweilers for extra protection. Because of this, a Rottweiler attacked Batman upon his arrival and fighting off the Batmen, resulting in a hideous scar and more protective gear.
Towards the end, the Joker had The Chechen taken away, threatening to have him cut up into pieces and fed to his dogs to see how "loyal" they are.
In their final battle at the Prewitt Building, the Joker used the dogs to attack Batman, injuring him further and allowing Joker to gain the upper hand. However, Batman managed to knock them off a ledge and killing the Rottweilers instantly.
- In the screenplay for the movie, the Chechen, upon his arrival, explains that he brought his rottweilers for the meet with Scarecrow specifically because he knew Batman would likely come, and also knew that the Rottweiler's powerful sense of smell can allow them to sense human meat even in complete darkness, thus acting as a deterrent against Batman's use of darkness to cow the criminal element. This explanation was ultimately cut from the film, although it was nonetheless implied.