He's an English Mastiff if anyone's wondering.
My friend had one that would carry 3-4 tennis balls in his mouth. You couldnt tell there was anything in there though, with those floppy lips...
He is the heaviest dog in the world, occupying a place in the Guiness Book, because of an English individual who weighed 155,48kg,(300 pounds)
The English Mastiff is indeed a giant, with a massive and long body, well defined muscles, a massive head and a powerful neck that impresses anyone that looks at him.
An ancient breed, over 4 thousand years, it was used in wars, combats and arena spectacles, where he had to fight bears and lions, and distingueshed himself for his ferociousness. Its temperament has been tamed since it stopped participating in these activities, and today may be considered a good family dog.
Even with his acute guarding insting, allied to his real and apparent physical strength, which make his an implacable attack in threatening situations, the Mastiff, when accustomed to strangers from an early age, does not have to be chained in the presence of visitors, because he may be docile and friendly towards them. He lays at their feet, rubs his head on their legs, raises his paws imploring for caresses, and then sleeps quietly next to them, with loud and deep snores, worthy of an animal whose average weight may be something like 200 pounds
after that he can hunt and eat by itself . lol 
