yo you guys are all word up retards reserch a breed before you talk abunch of bullshit about it fucking americans lol , American mastiff were breed from the english mastiff and anatolian mastiff , because they creator wanted a dog the look exactly like the english mastiff but did not drool has a long life span an very little hip related problems , my dog marley witch is an american mastiff she is an very alert dog , has a good sense when a threat is near,will protect if needed but is also a great family good, but when they are young introduce to other dogs alot or they will not get along with other dogs when there older. but if your looking for an good gaurd dog check into a rotti or a doberman insted or bullmasitff , but all four of these breeds require a experinced master