******** you say. If an intruder is trying to get into your house they want to do so as quietly and unnoticed as possible. The second that large dog starts barking they have lost the element of stealth and surprise. They also don't know what type of dog they are facing. Unless they have targeted you specifically for a very specific reason chances are very high that the intruder stops and goes elsewhere. No sense risking getting bit, having the cops called or at worst, getting shot because the homeowner has been alerted.
Right!
The overwhelming majority of the time someone breaks into your house it is for some sort of material gain. They do not want to shot you, even if they might if they feel cornered. They certainly don't want to contend with a dog and an alerted homeowner who may have called the police and may be armed. They want to slip in, grab something valuable and get out. If they are completely unnoticed then they did a good job of being a burgler. If they get the stuff and have to high-tail it out then they've only done a mediocre job. If they get noticed before they get the goods they have done a bad job. However, if they get in any sort of shoot-out, which draws a hell of a lot of attention then they have failed. If they get hit by a bullet then they are as good as convicted because you can't get a bullet-wound treated without law enforcement wanting to talk to you. If they know you know they are there and you have a gun then they most likely just want to get the hell outta there. All the talk of stopping power is meaningless. Buglars don't charge you after taking multiple gun-shots. They try to flee to avoid going to prison.