While I'm sure spats might help keep horse manure off the laces and hose, I doubt that had anything to do with their original intent. After all, spats didn't originate in London. Am I correct in stating that Scotland, and especially the Highlands, was never a place where horses were predominant like they were in the rest of Europe? From all I've read, there weren't a lot of horses used in Scotland.

Having horses myself (and being one who has cleaned up horse manure for many years, not only in my barn but also from draft horses when we would pull carriages in town), I have to say that horse manure is not nearly as messy as some might believe. It won't stick to your shoe like manure from other animals. As livestock goes, horses are pretty tidy poopers! The worst you'll get from walking through fresh horse manure is a thin film of wetness on your shoes or a few stray pieces of digested hay that fall off when they dry. Horse manure also dries fairly quickly into 'road apples' that you can pick up and crumble between your fingers.

To many modern city dwellers, it may seem gross. And living where I do, where people still ride horses in town, I always get a kick out of seeing tourists performing grandiose panic-stricken antics to avoid stepping near (or driving through) horse manure. But I am pretty confident that the common person in the era we're talking about would have thought nothing of it. My boots get dirtier walking through mud or wet grass than they do from stepping in horse manure. In fact, the larger threat of their day would have been the HUMAN excrement in the streets. That is most likely what would have filled Scottish streets rather than horse manure, I'll wager.