Wardogs are great from breaking pinned enemy infanty especially in the earlier periods. I will set them up behind my from line and once both front lines are fully engaged I will set all the dogs I have on them. This will normally cause them to rout.
That`s just how I do it, too.
Wardogs can pass through your own units easily, so they are perfect reserves. They can`t handle units very well on theit own, but if they attack a allready engaged unit they are devastating.
I keep them behind my lines and unleash them at the most crucial fights.Their added weight almost allway wins me that fight in seconds. While the dogs happily chase the enemys away, my infantery is in a perfect position to flank the fight next to it.
Of course, this works best in fights with lost of infantery on both sides.