There's an update over on the NUVIE page talking about what's new to the remake of the Ultima VI engine they're working on, complete with shots:

• Added boat support. It is now possible to buy a deed and use a ship or skiff. (screenshot) Rafts haven't been properly implemented yet.
• We've spent a fair bit of time working on actor support. Most actor types should display and move around the map correctly now. Some multi-tile actors are supported (cows, horses) (screenshot)
• Horsed party members. You can now use horses. (screenshot)
• Draw-bridge cranks and bells only animate when used.

They're also working on support for FM towns, assuming you have that version of U6.

So, for all you wierdos that like horses, support for those are now in.