Biology

Apparrently, it's not a good practice to cross-tie horses when transporting them for long distances. Apparrently it opens them up to respiratory disease.

You'd think that tying them up firmly while they were in the trailer would help them feel secure. Apparently this is just a human need, not a horse need. I suppose horses are used to the vibration and bouncing and swaying and all the bodily feelings one experiences at highway speeds inside a trailer, while humans are not. Also, horses don't seem to mind not being able to see what's happening or what's coming next in such an experience, while horses, used to running together at high speed without any forward sightline don't mind not knowing what's coming along the pike. They're used to this and so it produces no anxiety for them.