I couldn't agree more with Mehul that a large man with a knife could very easily get through any dog. It might be a little difficult if you have a 'schutzhund' trained dog - (those unfamilar with the term- schutz is german for protection- for more there is always google:)
Having said that, I would also would like to point out that any human being has a 'primal' fear of a large animal.
As we always see at our house, whenever a friend comes in, even when the dog is being friendly and just sniffing..they are put into the shock mode..they just freeze..I would do the same if a large dog sniffs me:)
The only advantage with an animal is when he gets into a fight mode...and you can't put him into flee mode(by a unexpected sound or something)..he is gonna come after you till his last breadth, knife or not..
And with humans with superior intelligence, we have fight, wait(caution- he's got a knife) and flee mode..Dogs don't have that, its fight or flee..
And about Indian breeds, as Mehul points out- There is the famous Modhul Hound and in south Rajapalayam..both are sight hounds..You get to see them quite often at the Bangalore Dog show..its in Jan every year..
I have still a long way to go to learn about pack behaviour and training dogs..my father is much better at that..I'll pick up soon..
But all said and done, our dog is for company and just telling us that the post has arrived..I don't expect him to keep burglars away..
And yeah he is a great company..always good to come home to a very happy dog with a ball waiting for someone to paly with him:)
pls..excuse the longish post