I heard a local shooter mention that using a retriever on dove is bad for their lungs. Something about the down being very fine or some such stuff. Any truth to this rumor? I was going to try my retriever on dove this Sept, but didn't want to do anything bad to her.

YES! Under no circumstances should you ever go near a dove field with a dog.
You also should protect you dog from the dangers of Dihydrogen Monoxide.
http://www.dhmo.org/facts.htmlChuck, some one is seriously pulling your leg! Next they will tell you never use pigeons for training.. Never use raised birds, only wild. My dog is so savvy, it can tell if a bird has been planted and flat refuses to point / retrieve it!
Pete