I really would like to see this as well. It seems that it should be a simple function to implement at a basic level at least. My main reasons for it are to allow for the possibility of a Military Working Dog as AD2001 pointed out, but also for general guard dogs attached to a VIP Target that must be assassinated. Most importantly for what I want to do right now I would really like to be able to group a bunch of goats into a herd led by a shepherd or two for ambiance in a mission. It would even be possible to create a Lone Survivor kind of scenario with this functionality. I guess you can create that dilemma scenario without the actual goat herd, but this would make it much more authentic.