Try the Millennium Horse

http://www.daz3d.com/i/3d-models/-/millennium-horse?item=2104&spmeta=ab

Here is a texture pack for it. Not sure if the horse is white enough though.

http://www.daz3d.com/i/shop/itemdetails/?item=2107

 

You can also get the Millennium Horse Unicorn addon which has a  very white texture.

http://www.daz3d.com/i/3d-models/-/millennium-horse-unicorn?item=2122

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi