I read ya post at work was about to answer on face value alone, but decided to leave it.
No pup is born stock proof and no dog dies stock proof.... Told to me many years ago by a top heading dog trainer.
Took me a few years to work out what the hell he was going on about.... But basically the temptation is always there.
As stated put ya dog away in a kennel when ya can't supervise it, teach it to ignore any stock but always be mindful the worse can and does happen.
Your dog killed a chook because of your fuck up, get a good kennel and run and some more chooks.
The upside is if ya can control her around chooks sheep and goats will be a walk in the park.
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