This dog breed is massive in size and can weigh up to 130 pounds. A bullmastiff has been known to overwhelm their owner and injure them at times. They have also been known to drool a lot and this translates to a lot of cleaning by the owner. This breed has a strong dislike for some other dogs and this means you cannot keep another dog in his presence. A bullmastiff should not be your choice if you will not have time for training.