WASHINGTON, D.C.--Kimberly Coyle of Central Valley, N.Y., on Dartani won the $10,000 Adult Jumper Championship on Wednesday, Oct. 23 at the Washington International Horse Show. Katherine Mercer on Colina SN won the $10,000 Children’s Jumper Championship, and Sophie Gochman on Colter and Caroline Signorino on Sandori were champions in amateur-owner...