Changespell
From WikiFur, the furry encyclopedia.
Doranna Durgin's fantasy novel Changespell, the sequel to Dun Lady's Jess, was published in paperback by Baen Books in February 1997, with the ISBN 0671877658. Back in her home, magical world, Jess uses spellstones and her own will to change between human and horse form, and must come to terms with her own feelings, particularly those towards her rider.
Changespell Legacy (2002) is the third book in this series.