Secret of the Night Ponies
This book is the best ever!
It is about a girl named Jessie Wheller who will do everything to follow her heart. So when Jessie discovers a neglected orphan girl and a captured herd of ponies, she is ready to come to the rescue.
With her Newfoundland dog, Blizzard, Jessie is never at a loss for helpful companions. And help is what she will need to survive a daring midnight adventure.