Have the front of your trailer open when travelling your horses? I've just seen a trailer on the motorway with it open...I would'nt dream of doing that on a open rode let alone a motorway! Or is it the norm?
I see that all the time - i work in an area where alot of people keep horses and constantly see trailers go past with the front top hatch open - i personally always shut mine - i dont think my horse would enjoy watching the motorway in its full glory! God knows what could happen.
Having sat in a car and experienced gravel and stones hitting up off the road, then the last thing I would want to do is risk that happening and hitting my horse in the head, or, god forbid, the eye.
Have accidentally done this once - Realised ned's head was out front when we went round the first roundabout, his tongue was out and everything (Think dog in car window!) Swiftly closed it.
this makes me so mad after seeing a horse been hit with debris at an endurance event. Only this weekend on the a12 I saw one travelling with top window open and on wrong side