LA CROSSE, Wis. (AP) — A new employee at Mayo Clinic Health System has made quite the impression. Patients stop her in the hallway to greet her and roll down their windows when she walks by in the parking lot to offer a quick hello.

Her photo ID says Luna Morgan, but the golden haired canine is known simply as Luna to staff and patients, joining the Mayo team in November as a facility dog. The sweet-natured yellow Labrador has quickly won over staff and patients in numerous departments with her gentle bedside manner, sleepy-eyed visage and arsenal of commands.

Two-year-old Luna, raised through...