COLLETON COUNTY, S.C. (WCBD) - A semi-truck transporting a racehorse overturned and struck another semi-truck on Interstate 95, blocking all southbound lanes on Saturday afternoon, according to Colleton County Fire Rescue. A semi-truck transporting a racehorse in a horse trailer was traveling northbound on I-95 near the 55-mile marker around 1:37 p.m. and…