Smart Strike, a Grade 1 winner and two-time leading North American sire, was euthanized Wednesday due to complications from laminitis. He was 23. The son of Mr. Prospector was a cornerstone of the Lane’s End stallion roster, in the midst of his 18th season at the Versailles, Ky. farm. His stud fee was $100,000 in 2015. Smart Strike was known as one of North America’s most versatile stallions, siring elite runners on all surfaces and in several countries. He was North America’s leading sire in 2007 and 2008, coinciding with the two Horse of the Year campaigns of his greatest son, Curlin.