At Trenton High School he was active in tennis, student government, and on the staff of the school newspaper. At Princeton he majored in biology and graduated with honors. He was on the track team and ran cross-country. He belonged to Tower Club. After Princeton he went on to the College of Physicians and Surgeons at Columbia University. He was a lieutenant junior grade in the Navy before his internship at Bellevue Hospital in New York City.
He moved to Trenton, N.J., for a private practice before he became chairman of the medical department and medical director of the Mercer Medical Center.
Horace is survived by his second wife, Joyce, to whom he was married for 42 years; his children with his first wife, Lois: Pamela Leeds, Richard Shaffer, and Jill McGlone; stepchildren Wendy Kraus (Mitch), and Rob Bear (Cindy); grandchildren Andrew, Lindsay, Shana, Mariah, Danielle, Samantha, and Max; and great-grandchildren Reid and James. His oldest daughter, Karen Shaffer, predeceased him.