Lydia Adamson: Dr. Nightingale Races the Outlaw Colt (USA 1998)

From the Publisher:
Dr. Deirdre Quinn Nightingale is just setting down to some fun after a long night spent saving some local dairy cows, when a young police officer is gunned down outside a local restaurant. Once again, it's up to Didi to do some moonlighting to solve the mystery. And along the way, she uncovers something even more baffling--a runaway colt mysteriously linked to the murder. Now she finds herself confronting a cold-hearted killer burning with revenge and with a sinister plan to strike again!

Lydia Adamson: Dr. Nightingale Races the Outlaw Colt. Signet, ISBN: 0451188152 (January, 1998), 224 p., $5.99.