So sorry to read about your chickens. That had to be horrible
We spent over $400 on a used chain link kennel for our dogs after one of them killed 3 of the neighbor's chickens. I have chickens obviously and the dog never harmed any of mine. But one night we were outside working on the new chicken run, and the dog was laying right there with us the whole time, and then he was gone. Just disapeared! We called and called him, we walked the property, we look everywhere. We could NOT find that dog.
Then all of a sudden someone drove in the driveway with the dog running beside his car. He was furious and said the dog killed 3 of his chickens, ripped into his duck pen, and was going after his Golden Retriever puppy. He said that if he had gotten hold of the puppy, he would have killed it. He said he actually didn't care about the chickens, they're just pains in the @ss anyway, and his wife lets them free range with no coop or no run. But it was his puppy he was terrified for.
The next day I spent hours on Craigslist looking for a suitable run. It is 11x17 feet, and all 3 dogs can stay in it every minute that they're not on a cable, or in the house. NONE of them get any freedom to hang out with us at the barn any more.
I feel so horrible that it happened, but I wouldn't call myself irresponsible. The dog did something very unexpected, and uncharacteristic. He is part Lab and he's just a big dumb teddy bear that loves to hang out with me while I do stuff around the farm. He is (was!) constantly by my side, and was the perfect companion dog. But he did that and now he's locked up. PERIOD.
When we have animals, things just happen. Particularly with dogs who are natural born predators. They have a prey drive and they are roamers and migrators by nature. I learned to never trust ANY dog, regardless of how well trained and gentle they are. ALL animals are unpredictable, and especially predators are.