Hmmm. Ideally you need to start when the dog is a puppy and smaller than the chickens so he/she is intimidated by them. Once pecked on the nose your dog is very unlikely to chase chickens.
If the dog is older you must not let it get away with chasing the hens even once. Put it on a lead...
Thanks, Lydia - very re-assuring. I've just been away for a week and these problems manifested themselves on my return. The hens were looked after by a very knowledgeable young man who keeps chickens himself so I know they were well cared for. Maybe they just missed me!
One of my three Bluebells, all now three years old, has started to lay some very strange eggs indeed. To begin with they were tiny and hard shelled, like small pebbles, Now they are like long, pale snakes, thin shelled, watery and yolk-less. Another is laying thin shelled eggs which break as...