OMG, how horrible for all of you. Duke didn't mean to do something awful, instinct just took over. I don't know what sparks prey drive, but I know my husky has plenty of it. Star grew up with ChowChow,my RB kitty, and never raised a paw to him. Rosie, my other dog at the time, was scared to death of the cat. But when we moved, they were in the kennel outside and Chow happened to walk through one night. They both launched off after him. They were so fast, I was just dumbfounded. Fortunately I was close enough to save him, but I couldn't believe how they acted. I never let him outside in the same area as them again. Now, they were all inside together again, and ChowChow was extremely cautious, but they never bothered him inside.
I don't believe you can train prey-drive out of a dog, it's hard-wired into their genes. All we can do is be aware and do what we must to keep everyone safe.
I am so sorry about your kitty boy, I hope your son can understand it wasn't something Duke had much control over either. It just happened.
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