Hello, I am the owner of a 13 week old French Mastiff puppy - a male not neutered of course. I have had him since he was 9 weeks old. This is my first dog I have owned and raised on my own so I am new to understanding and learning behaviour. My puppy is not vocal, he occasionally wines and growls during play, other then that he does not bark. He is not mouthy at all and prefers to chew his toys over my hands, so far I have had no issues with this. He is affectionate, he waits for his food, he is learning eye contact and maintains it on walks and he is very responsive to training. I am able to take food from his mouth eg pigs ears and he does not complain or growl. The issue I am having however is his behaviour when he engages in play. He has mounted and humped every dog he has met, and while he does these things he growls and refuses to get off them. I physically restrain him in order to make him stop, and when I do he growls at me and tries to snap at my hands to make me let go. He is now getting bigger and I will not be able to physically grab him that way. He has not shown any aggression to other dogs, he walks past barking dogs fine and does not engage, but he does play incredibly rough and is highly excitable and not able to calm down. My other issue which has formed over the last two weeks is that when he gets into these mental states of play eg ripping up shoes and getting the zoomies, I am unable to control him as like I said if i try to restrain him I am met with a deep growl and snaps. I am unable to differ between play and aggression as he only gets like this when he is playing rough. For example if he plays very rough with a stuffed animal, he must instantly hump it, if I attempt to pick him up or move him during this time he will growl and snap at me. So this is why I am confused as this only occurs when he is in a very rough playful mood. I am desperate for help and am unsure on what to do and am unsure if his growls at me are just him still being in that playful mood. Thankyou.