It is always fun to play around with shadows. There are a thousand different shadows you can catch with your camera and your horse. In this post you can see photos of a horse reflected on a wall. We were inside during this shooting which limited the light source so I had to press the Iso value pretty high. I am not a big fan of high Iso but sometimes you do not have a choice.
To get a sharp shadow of your object you need to have a strong key light and place it a few meters from your object. If you go closer with your light the shadow will become more blurry. On this shooting we used a strong key light placed in front of the horse and about 8 meters from the horse.
Try this out and tell me how it goes! 🙂