Our toy hauler has a sliding glass door that separates garage and living area. I do not notice any odors from toys when the door is closed and toys are in garage, however I would wonder if your horses would be as odor friendly rather in or not. Do you think there will be enough ventilation for the horses while traveling? I do not know anything about the requirements of horses while traveling, just wondering! Also, for me anyway, I would consider if hauling horses in a toy hauler would have a negative effect on resale of the r.v.?