I had a goofy, playful halfbreed... he was goofy and playful right up to the time that the hunt switch was flipped, then it was all instinct, then it was goofy and playful again. God help anything that was considered prey for the play!
If you want to see a contrast, watch an Irish Wolfhound wandering around the backyard... and then it notices a roo... a very dopey, affectionate, adorable, social, highly efficient killing machine capable of bringing down even the biggest of men.
You haven’t seen a bluey natural instincts until you have seen its eyes red and popped out of its head while its jaw locked onto something. Our bluey is a sook towards humans but what ever other animals it sees as prey and those instincts kick in.
I had an staghound cross blueheeler cross pitbull cross bullterrier for about a year and a half.He was a pup and was due to be put down so i thought i would give him a chance.He was friendly obiediant,goofy and playfull...untill he saw another animal.Nothing could get through to him, full kill mode 
This dog brought down a small roo at 6 months old
From then on he would want to kill everything he saw and did several times,assorted animals.
At a year and a half he wieghed in at 75kg's.
One day he bashed two pallings out of the fence and grabbed the next door neighbours full size staffy.Had him by the top of the head in a death shake The thing that brought my attention to the fight was the staffys owner screaming.Sounded like a child....i'll never forget that feeling..thinking he was attacking a child
.
That was the last day of the dogs life.I really loved that dog, he was my mate.But i coudn't trust him and coudn't call him off a kill.So its all i could do.
It was the right thing.
