I had a pure saluki that killed pariah , (wild), dogs , but I’ve never seen a 12 week old pup of any breed kill a grown dog.
Milk teeth could give you a scratch that gets infected, rabies or such like, and you die of rabies, but c’mon, you’re talking to grown men, who mostly have had working dogs all their lives and you expect us to believe a 12 week old pup killed a grown dog ?
Your mate is having you on ! LOL !
Cheers.