[Scythian]

That's because dogs are more sensitive to demonic spirits than men and will bark at them.

Is that sarcasm or are you serious?

[Centurion2000]

Is that sarcasm or are you serious?

Seriously, dogs have always been thought of as more sensitive to the supernatural.

I think one reason that the "dogs are to be killed" in the Koran is that it is satanically inspired. So, kill the watchdogs against supernatural influence, namely dogs.