I have a Boston Terrier, he's 6 now, he's always just been around the birds while in thier runs. We made no real efforts to train him other than to tell him no when he seemed too interested in thier food or activities. They past few years it has only been quail, but this year we got chickens again. The youngest (12 weeks) just started getting to roam the backyard freely, normally when I let the dog out I put up the chickens first. Well the inevitable happened and my husband let the dog out without checking for the birds and thankfully everyone was fine. So I put the dog on a leash and took him out with me the next time to see how they were reacting to one another. Complete indifference! So I think like many animals, familiarity makes the biggest difference. Obviously no birding breeds or anything with a huge prey drive like rat terriers, and there's always the temperament of the individual dog, but I think applying the same see no touch kind of scenario we do with introducing chickens to one another is very helpful. If you want to adopt you could always consider taking a chicken in with you to see the dogs reactions
most rescues allow you to bring current pets as long as they're up to date on a vaccinations and I don't think that applies to chickens 

