Add side-to-side movement to the tail:
1 Make sure Auto Key and Angle Snap are both on.
2 Activate the Top viewport, if it isn’t active already.
3 At frame 1, select the lowest link of the tail, Bip01 Tail.
4 Rotate Bip01 Tail to the dog’s left, – 15 degrees in the local Y axis.
5 Rotate the remaining three tail links in the opposite direction,
to counter the side-to-side motion of the spine.
Animating a Quadruped Walk | 1037