Ears

Starting from the legs and working our way up, we've finally made our way to the ears. To make our lives easier we need only to animate the right ear and then copy the frames onto the left ear.  

So lets start with selecting the "rt_earlow_CTRL" and at Frame 3 when the horse is completely hovering in the air, Rotate X the ears so they're almost vertical. This will depend on the angle of your horse's head.

And at Frame 12, when the horse has landed and the head is at it's lowest near to the ground, rotate the ear back even further to about 70. As the horse is travelling fast, the wind pushes the ears back. 

In the graph editor shift Frame 12 up a little to around 60, as we don't want the ears to be too exaggerated. Then smooth out Frame 3 so it creates a pointed curve as shown. This means the ears will be pulled back for longer and flick forward quickly.

After we've finished animating the right ear, select all of it's keys in the graph editor and copy them. Now select the "lf_earLow_CTRL" and in it's Rotate X right click and open up the "Paste Keys Option" menu. Make sure your settings are the same as shown above, specifically the "Paste Method" set at "Replace" and "Replace Region" at "Entire Curve". Check the "Connect" box too. 

Delete the left ear's last Frame 16 and paste the right ear's cuve onto the left ear. It should automatically connect to the first frame and be similar to the above.

Now we've completed animating the horse's upper body and here's a play blast of what you should have achieved.