Unfortunately, the Rottweiler Bullmastiff mix doesn’t do well with other dogs as these canines like having the entire house for themselves. Furthermore, this pooch has a high prey drive, which is why it is probably not a good idea to have a small pet next to your Bull Mastweiler. These are the traits inherited from Rottie puppies mostly, as Rottweilers can display occasional aggression. Still, properly-socialized puppies have a good chance of becoming friends with other dogs, especially if you socialize them from an early age.