I've got to adult shepards mixes who never touch or bother the chickens.
I've had ferrets and a dove that climbed on the dogs and were essentially my training aids...so when I got chickens...they knew they better "be nice." And I've been fortunate enough to never have a problem.
When my old shepard female passes and I decide to get a puppy...well, I can see where thorough training will have to be had...because I can see where a playful puppy might think it fun to chase...but with training, I expect a good dog like the ones I've got.