You are in a tough situation. You love your retriever, and you also want to protect your flock. I arrived home from work one day to find that a stray dog had entered my coop and killed half of my hens. He was still in the coop when I opened the door. I could have easily "trapped" him and used lethal methods to exterminate him but I did not. The dog by nature, is a predator. How could I kill a puppy? The chicken, by nature is prey. It could have been a fox, a hawk, or other predator that attacked that day... I shooed him away and dealt with the clean up. I never saw the dog previous to the incident nor have I seen him since. After this incident, I never free ranged my girls again. I realized that it was MY responsibility to protect my girls.
Once your golden has a "taste" for game and knows where she can get more, the problem will continue. There are some easy solutions that could also help. Use welded wire for covering the walls of the run. Chicken wire is useless as dogs can tear it from its attachment points and enter through a hole that they have created. I have ALSO added polycarbonate paneling to the walls to protect the run from wind/rain/snow. The run has a roof as well. Dogs can and will jump over a fence/wall to get at chickens so covering the area is important. Lastly, dig down a foot or so and bur welded wire hardware cloth. Back fill with dense soil/gravel to prevent animals from digging UNDER the run.
An invisible fence surrounding the chicken area may also help but some dogs will endure the shock if they are motivated enough to get what they want. Good Luck.
