The Washington International Horse Show Official Poster. Photo courtesy of Jennifer Wood Media Win a pair of tickets to the Washington International Horse Show The 56 th  annual Washington International Horse Show is upon us and  Sidelines  is thrilled to be able to give away one pair of tickets — that’s TWO tickets going out to one lucky winner and their friend! The WIHS will be held October 21 -26 at the Verizon Center in Washington, DC.