By Tom Victor Trainer Nicky Henderson has led the tributes to legendary horse Shishkin, who has died aged 10 after suffering a fracture to his hind leg. Shishkin last raced on April 11, with Nico de Boinville the jockey. The horse had been due to leave for Punchestown, where the 2024 festival is set to get underway on Tuesday. Henderson-trained Shishkin claimed a win as recently as February at Newbury, setting up a potential run at the Cheltenham Gold Cup the following month. This wasn’t to be, though, with the 10-year-old withdrawn from the race. Shishkin was a winner at Cheltenham in 2021, c…