Tigger, if you read all of my posts, you would know that I worked as a vet tech for 12 years. I have also fostered a LOT of animals I brought home from work. I've even volunteered for a horse rescue for a couple of years. I'm well aware that castrating will not eradicate aggressiveness in all cases--but in many cases, it DOES. So I was doing everything I could to at least try to reduce his aggressiveness.
I did plenty of homework on this breed, but even though I've dealt with many very aggressive dogs over the years, this one, as I said, is by far the worst I've ever seen.
Taking in an older aggressive dog? No. I've had this dog since he was 8 weeks old, spent thousands of dollars to save him when he had Parvo, and never had chickens before. I've wanted chickens for at least twenty years now, but never got any because I've always had dogs. This is why I'm seeking help on this forum. I want to keep them safe from the dog when I do get them! I have no way to keep the dog out of sight of the chickens. We live on 2 1/3 acres, fully fenced. The dog runs free within the fence, and keeps undesirables away effectively. He's completely changed. I don't know what happened, but he hasn't attacked anything in years. But like I said, because of what has happened in the past, I want to be sure the chickens will be secure.
And yes, we are planning on staking the heck out of the run, making it go through the hardware cloth and using a hardware cloth skirt all the way around.
I've heard about hog rings, Capricorn. The guy who wanted to charge us $1000-1400 to build a run mentioned them. We couldn't afford that, and on top of that, we are getting up in age and have no building skills, which is why I keep asking so many questions on this forum.