the official translators seemed to be confused about it too because they called her “he” in one of the omakes but yeah! Den is a good girl and the best dog. FUN FACT ABOUT HER: she lost her leg saving Ed from getting hit by a train (the info is from an artbook and the screencap is from a game):
Another fun fact, she knew who Al was even after he lost his body and looked after him when he ran away (this is from an side-story that wasn’t officially translated over here):
and she’s top dog. this is the omake where the translators were confused about her gender:
FMA appreciation life 