hi all, 
l'm new to the forum, and have recently been given a staffy x bullmastiff (who we think is 9weeks old). Boof is much more dominant in the looks department of a staffy. 
In the last couple of days, he has been a bit more nippy and biting with me rather than my partner. I know he's only a puppy and when he does growl/bark/nip/bite/chew, he does usually have a wagging tail.... but l am concerned it can be an underlining problem that could turn more serious in the future. 
We've had him for just over a week now and are trying to toilet train him.  
any suggestions? 
Thank you, 
Szandor