America’s richest Standardbred racehorse in training will be taking some time off.

Surgery to remove bone chips from the knee of seven-year-old gelding Mr. Muscleman will keep the campaigner off the trail for a few months, according to the US Trotting Association.

Patricia Hogan, DVM, DACVS of the New Jersey Equine Clinic in Clarksburg, New Jersey performed the procedure on Mr. Muscleman, who is trained by Noel Daley and owned by Adam Victor & Son Stable. The horse has won $3.5 million in his career.