Has anyone else ever wondered why some stallions, such as Big Macintosh and Shining Armor, have hooves coloured differently to the rest of their bodies, yet most others don't? And even more strangely, Big Mac's hooves were the same colour as the rest of his body as a colt, yet Trouble Shoes' were even whiter than they are today?
Theory 1: Blood Pressure
The reason that some heavy stallions have coloured hooves may be their higher level of blood pressure. This may also explain why Trouble Shoes had whiter hooves when he was shown as a colt in the rodeo, as his apparent higher level of activity would have increased his blood pressure, thus increasing the whiteness of his hooves. Big Mac, on the other hoof (literally), grew up with much slower-paced activity.
But what about ponies like Gladmane, who appear the same weight as the likes of Big Mac, you may ask? They're just a different type.
Then again, I'm no scientist. Maybe Trouble Shoes' hooves simply got browner the same way my Converse shoes have (even though they're only two weeks old). They didn't get much whiter when he came back into the rodeo as a stallion. Or maybe it just differs from pony to pony.
Theory 2: Skin Loss
This theory suggests that while all stallions are born with furry skin around their hooves, there is one kind that loses that skin with weight. The reason Trouble Shoes lost his hoof skin at an earlier age than Big Macintosh may simply be that he had weaker skin.
As for if mares can have coloured hooves, I just can't say.