I once read an account from colonial India (possibly by Kipling, as I recall) where the family residence of a British administrator was entered by a tiger in the middle of the night, and found itself in the bedroom of the children. The family dog, a progenitor of today's 'pit bull' breeds, gave it's life in defense of the children, but held the tiger at bay long enough that the father had time to respond to the commotion and to properly dispatch the cat.
Good dog ;~D
My dogs are afraid of small cats, let alone 800 pound ones.