Dont know if its been put up here yet (9 pages in 2 days? seriously?) but here is a bit on info on blue heelers, often used as cattle dogs here in australia
http://en.wikipedia.org/wiki/Australian_Cattle_Dog, In my experience they arent a big dog, (bout knee height on a human), can be fairly vocal if someone they dont know is on the property but will do the good guard dog thing and stand off and bark rather than getting in the intruders face, they can be smart as hell and ive only seen them 'have a go' if they are really being treated harshly. Frankly they are nothing a full grown adult should be seriously worried about, if you laid a boot into one you could get it airborn.
I find it almost impossible to have any sympathy for the cop, he was either shitscared in which case he should never have picked up the badge and gun in the first place, or a fairly twisted/powertripping individual (again, shouldnt have access to a gun and badge).
<10 seconds of calm speech without waving a gun around could have prevented the whole thing and if it was the house with the domestic, 10 seconds isnt going to make any difference to someone inside if there is no yelling or screaming.
Better than the usual caper when they are shooting humans though I suppose