Meatball is my unneutered cross, he's about 10 months old...he's been fine, raised amongst the other 5.  Since I've been home, he's taken to growling at Spock and snapping at him.  There is no apparent reason although I'm sure there's a doggie reason in there somewhere.  Spock can be standing still, sitting down, sleeping, doesn't matter.  Meatball will approach him, curl his lip, growl and lunge.  Any ideas?