I am really sorry to hear that your dog Duke killed your kitty.. My dog Tikeya, killed my RB Rabbit Angel, and my brothers kitten too.. She just chased them and they had heart attacks... but its killing none the less.. Somtimes a dogs prey drive is just too much for them to keep pent up.. I would seperate your other kitty and Duke from now on.. Again, try not to be too mad at Duke, dogs will always be hunters... (((hugs)))