Sorry to hear you lost one. It happens whether it be your dog, a stray dog, a hawk, raccoon, weasel, etc. It's important that you train your dog & teach it that the chickens are part of the extended family. We have a Schnauzer, they were breed to hunt rodents and mine loves to hunt....we live in the country. When we decided to get chicks we included her in every activity pertaining to the chicks....feeding, handling, observing, changing brooder, etc. (always in arms reach or on a leash) We allowed her to observe them and while observing them kept telling her....babies, nice, friends and a firm NO if she got in attack mode or excitable. When they were able to free range we allowed her to be out on a tie out & sat with her knowing that the chicks would approach her.....again keeping her in arms reach & reinforcing the fact with words...chicks, nice, friends, and sometimes a NO! She goes out with us whenever we go to collect eggs or feed. She gets excited when we ask "You wanna go see the chickens?" for she knows if they are getting a treat she will too!