This mod changes:

Horse's mesh;
New textures (diffuse and normal maps) for all Skyrim horses;
Horse's and horse rider's animation (idle, walk, trot, run and sprint);
HDT Hair physics for horse's mane and tail;


Requirements:

This mod requires the latest version of HDT Physics Extension .dll and SKSE.
Tested on v.14.28 of HDT.

Compatibility:

This mod IS NOT (!) compatible with any horses saddles/armory mods!
Only saddle's texture mods probably.

I'm not sure about this mod compatibility with other HDT-related mods.
You may try if you wish, but please make backup of your savegame firstly.

Warning: this mod still have some issues that have to be fixed.
Use in on your risk and don't forget to make the backup of your latest savegame.

Installation:

Install the downloaded archive with NMM and place HDT .dll file to your \Data\SKSE\Plugins folder.
There is no HDT Physics Extension .dll included in this mod, you have to download it manually (just google it).