

During World War II, the family moved to Vallejo, California, where Jack’s father worked for the Navy. Following the war, they moved to Colorado where Jack attended Columbia Heights Elementary School and graduated from Wheat Ridge High School in 1956.
Fondest memories of his childhood include the years working towards his Eagle Scout recognition. Jack began college at Iowa State University, but his love of Colorado and a deep respect for animals ultimately drew him back to Colorado State University to pursue veterinary medicine. It was there that he met his wife of 65 years, Judith “Judy” Anne Sigler, and became Dr. Makens. He and Judy married in 1961 and moved to Britton, South Dakota, where he practiced large-animal veterinary medicine. One year later he commissioned into the United States Army Veterinary Corp. As Captain, his military service took him to Washington, D.C., where he was assigned to the Pentagon. Part of his duty was to care for the caisson horses used in military funerals. During President Kennedy’s funeral procession, he walked near Black Jack, the riderless horse, ready to provide care if needed. He served at the White House during the Kennedy and Johnson administrations providing veterinary care to their pets.
After completing his military service, he practiced near Kenosha, Wisconsin, before moving home to Denver and opening a small-animal veterinary practice, the Hampden Veterinary Clinic in Englewood, Colorado. He served as president of the Colorado Veterinary Medical Association, was honored as Colorado’s Veterinarian of the Year, earned recognition on American Veterinary Medical Association's honor roll and presided over the grand opening of Colorado State University’s new animal hospital alongside then Governor Richard Lamm. In retirement he was often seen visiting friends, reading and working on a multitude of house projects for himself and his children - always in his beloved orange “bug” or “big blue” the farm truck. In all, always witty, selfless, patriotic, chatty and sassy.
He is survived by his wife, Judith; his children, Thomas (Garden City, Ks), Ellen Stark (Denver, Co), Daniel and wife Monica (Las Cruces, NM), Timothy (Urbandale, Ia), Matthew and wife Hillary (Castle Rock, Co); his seven grandchildren; his six great-grandchildren; his brother James “Jim” (Granbury, Tx) and sister Mary Pat (Las Vegas, Nv) as well as many nieces and nephews.
Jack was hard working, committed to his faith and a lifetime of learning, a friend to many and a beloved husband, father, grandfather and great grandfather.
A funeral mass will be held at St. Francis of Assisi Catholic Church on August 6, 2026 at 10 a.m. with burial to follow at Cedar Hill Cemetery in Castle Rock. In lieu of flowers, memorial contributions may be made to St. Jude’s Children’s Hospital, Catholic Charities or other charities close to your heart.
Visitation will be held at Olinger Andrews Caldwell Gibson Chapel, 407 Jerry Street, Castle Rock, CO 80104, US, on August 5, 2026, from 6:00 pm to 7:00 pm.
A Mass of Christian Burial will take place at St. Francis of Assisi Catholic Church, 2746 Fifth Street, Castle Rock, CO 80104, US, on August 6, 2026, at 10:00 am, with a reception to follow services at the church fellowship hall.
Reception to follow services at the church fellowship hall
Military honors will be presented at graveside.
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