re: "the horses trotting on pavement all I can think of is "road founder".
While I didn't watch the whole thing, when I rode in Ireland, we trotted on the roads in order to leg the horses up for the hunting season. Their belief was that there was no problem with trotting - just didn't canter because the horses might slip. I never saw any problems caused by it.
I saw something similar in an episode of Midsomer Murders a few years ago. At least they weren't racing on pavement in that episode. It was Travelers, and they were racing pacers and trotters against each other.
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