Both of our girls LOVE horses!  Their grandparents gave them several horse books which have quickly become some of their favorites.  One of the ones they enjoy is Belle by Elizabeth Mills.  The book is about a girl named Emmy who moved from the country into the big city.  Emmy loves horses and misses her home in the country but soon finds a stable were she can go riding in the park.  The horse she rides is named Belle who helps her adjust to living in the city.  If your child is starting to read independently and enjoys animals (especially horses) they will probably like this book.