1/2 Of me would be SO ******.
The other half of me owns dogs and knows that they are indeed dogs. I tell my wife all the time "stop yelling at the dogs for being dogs".
Glad he was hospitable about it!
So the 1/2 of me that would be ****** would also tell you to call animal control - but im not sure that the dog did anything wrong - I know if the dog attacked another dog or a human - there would be some definite consequences. Attacking chickens? Unless the owner knew that his dog did not do well with chickens, and knew that you had chickens that were not well protected, and still let his dog out to possibly kill your chickens - im not sure that anything will be done even if animal control comes out.
The other 1/2 of me that owns dogs and knows that even putting 100% of my energy into training my dogs 'right vs wrong', and keeping them in my own yard, and yelling if they run away but they run away at least once every couple months no matter what I do - I would tell you not to knock on his door next time his dog kills something in your yard - now it's your job to either build a better coop, put up a fence, or both.
Not sure how much land the two of you have, and not sure how interested either of you are in putting up a fence - but you could ask him to contribute 1/2 to the cost of a fence. If he refuses, tell him to be ready to keep buying you chickens, and pay you for "emotional loss", and to buy you eggs while you're waiting on new chickens to grow up, and for coop repairs any time this happens...