Mastiff puppies are much like teenagers and go through a rebellious phase in their lives when they are still young. I know this because both of my Mastiff puppies went through this rebellious period. For me it seemed like they were actually teenagers because every chance that they would get they would try to test the limits to find out what exactly they could get away with and what they couldn’t get away with. However, here are some ways that you can handle a rebellious Mastiff puppy and correct them back to the way you want them to be.
The first way that you can correct this problem is by standing firm to your rules. If your pet detects that you have any sense of giving up any ground they will take advantage of this and push the envelope to the point that the seal is ready to break and then when it does break you will have even more problems of getting them back to the point that you started off at if you are even able to reach that point.
The second way to help solve this problem is by having them take a first or second obedience course. I know that for some of us this can be expensive, but it is possible to do this because it will help you learn how to correct the behavior quickly and then you will not have to worry about them creating even more trouble for you. So I would highly recommend using an obedience training course as well as hold your ground.