Dr. Jonathan Gilmore Mercer

Jonathan Gilmore Mercer, DVM
August 1, 1935 – April 5, 2026

Jonathan Gilmore Mercer, DVM, of Sunnyside, Washington, passed away on April 5, 2026, at the age of 90.

Born in Akron, Ohio, Jon was a proud graduate of Buchtel High School, Class of 1954, and went on to attend The Ohio State University, where he played both soccer and lacrosse and was a member of Phi Gamma Delta. A standout athlete, Jon was captain of the lacrosse team, was named All-American in 1957 and 1958, and remained a lifelong Buckeye. He continued his studies at The Ohio State University College of Veterinary Medicine and was a member of Omega Tau Sigma, earning his Doctor of Veterinary Medicine degree in 1962.

Following graduation, Jon was commissioned in the United States Air Force and moved with his wife Carol to Larson Air Force Base, in Moses Lake, Washington, where he served as a veterinarian, as well as the base food inspector and primary caregiver for teams of German shepherds that guarded the base perimeter around the clock. Having spent two summers working on cattle ranches in Eastern Oregon, Jon had long dreamed of moving west. The Pacific Northwest - with its mountains, rivers, and wide-open spaces - proved to be exactly what he had hoped for. During their time at Larson, Jon and Carol formed lifelong friendships and made many lasting memories.

After completing his military service, Jon and Carol briefly lived in Coos Bay, Oregon, where he worked in a small animal clinic before purchasing a veterinary practice in Sunnyside, Washington. There, he would dedicate more than 50 years to caring for both large and small animals. By the early 1990s, he shifted away from the more physically demanding large-animal work, focusing primarily on companion animals and developing particular expertise in ocular care. Jon’s practice was known for its open doors - he never turned away an animal in need. Though often a man of few words in the exam room, his compassion, skill, and deep connection to animals were unmistakable to all who observed him.

Deeply involved in the Sunnyside community, Jon was a longtime Rotarian and Paul Harris Fellow, a devoted supporter of high school athletics, and a fifty-one year member of the board of Sunnyside Community Hospital, generously contributing his time, intellect, and leadership.

An outdoorsman, Jon found great joy in backpacking and exploring the Cascade Mountains, including having summited both Mount Adams and Mount Rainier. He also loved time spent on the tennis court, playing bridge, or gathered around a table with family - dealing cards, flipping dominos, and enthusiastically defending the official rules when his opponents sought to make mid-game adjustments.

Jon remained active and engaged throughout his later years, never hesitating to hop in the car with Carol and travel many miles, in any direction, to watch their grandchildren compete in athletics. You name the sport, Jon knew the rules, offered thoughtful coaching advice, and cheered as a devoted fan! His presence on the sidelines was a powerful expression of confidence, pride, and love for each family athlete. Blessed with many valued friends in the Yakima Valley he spent time sharing friendly poker games, participating in a spirited fantasy football league, enjoying long drives, and simply sharing a joke and a quick conversation.

Jon is survived by his beloved wife of 64 years, Carol Jo; his children, Jonathan (Paula) Mercer of Whitefish, Montana; James Mercer of Yakima (Tina of Lake Stevens), Washington; and Mary Lou (Trent) Green of Portland, Oregon. He is also survived by his grandchildren, Addison James, Quinnton August, Jonathan Douglas, Sophia Hunter, Muriel Alexandra, Mary Margaret, Abigail Mercer, Elijah Robert, and Marcus James, each of whom he keenly knew, loved individually and deeply, and provided him the utmost pride and joy.

He was preceded in death by his brother and sister-in-law, Dr. James and Jean Mercer; his sister, Jean Allison; and his parents, Dr. James Raymond and Hilda Mae Mercer.

A celebration of life will be held at Smith Funeral Home in Sunnyside on June 26th at 12pm.

Dr. Jon will be deeply missed by all who knew him—family, friends, and all creatures great and small.

In lieu flowers, memorials may be given to Astria Health Foundation where Dr. Mercer spent over 50 years serving as a Hospital Board member. Donations can be made via check payable to Astria Health Foundation, with “For Astria Sunnyside Hospital” noted in the memo line, and mailed to: Astria Health Foundation, PO Box 719, Sunnyside, WA 98944.

Alternatively, gifts can be directed to Washington State University Veterinary Teaching Hospital Operating Endowment. Dr. Mercer had a longstanding relationship with WSU’s Veterinary Hospital both in continuing his required training and education as well as referring complex cases for advanced care. Donations can be sent via check to WSU College of Veterinary Medicine, PO Box 647010, Pullman, WA 99164-7010. Please add “Dr. Jonathan Mercer” as the memorial name to your gift.

Those wishing to sign Dr. Jon’s online memorial book may do so at www.funeralhomesmith.com  Smith Funeral Home in care of arrangements.

To send flowers to the family or plant a tree in memory of Dr. Jonathan Gilmore Mercer, please visit our floral store.