Remember how certain people were saying that the exploding pigs weren't a "real" unit in RTW.
They shouldn't be eliminated at all from anyones' RTW game at all.
A book called "Greek Fire, Poison Arrows, and Scorpion Bombs" by author Adrienne Mayor actually mentions the pigs as being covered in pitch, set on fire and let loose against elephants.
Keep them in the game folks.
There was never any arguement as to whether they were ever used. The fact was that the pigs were used only a handful of times and were never that effective. To say that they played a minor role in ancient warfare would be giving them way too much credit.
Except that the point of an interactive game is to shape history, not relive it, which could be done better by watching the History channel or reading a book. So pigs and dogs were used, in a small scale. But now you're the leader, not some ancient dude who thought animals were not worth it. Maybe you want to create an entire army of dogs and pigs and found that the hilarity is worth the coin. That's your choice.