Horses, Chapter Books, Royalty 

Chevalia is an enchanted island where ponies and horses rule, its magic powered by eight golden horseshoes hanging in the royal castle. But the horseshoes have been stolen and must be found before Midsummer Day or the island will lose its magic . . . The Special Secret It's Harvest Day on the magical island of Chevalia. Pippa and her Princess Pony friend Stardust head to the grasslands to help - and to search for the missing horseshoes. But Stardust decides that princesses shouldn't get their hoofs dirty doing farm work after all. This upsets her friend Mucker, who works on the farm. Perhaps if Stardust can overcome her pride, they might uncover another missing horseshoe in the fields. The third in a fabulous series of six books filled with spooky Night Mares, unicorns, Princess Ponies, and rip-roaring adventure. - from Amzon