Like the last poster said dogs will be dogs. If you own chickens long enough eventually you will have to deal with coccidiosis and it can hit dogs hard, but its as easy to deal with in dogs as it is in chickens. You just have to catch it. They will get as sick as if they have parvo. You treat them with sulfa right along with your chickens. Hopefully you won't have to deal with this anytime soon though, its just something to keep in mind for you and anyone who owns both dogs and chickens. Of course, dogs are succeptable to coccidiosis from wild birds as well, so even if you keep them away from your chicken area that doesn't make them safe. I wouldn't bother trying to keep him away, I don't with mine. I want them as close to my chickens as I can get 'em to keep them safer from predators.