CHELTENHAM, England -- The opening day of the prestigious Cheltenham Festival was marred by the death of a horse in each of the final two races on Tuesday.
Mossback had to be put down after suffering a shoulder injury in a fall during the National Hunt Chase. Report To Base was put down after falling in the Close Brothers Novices' Handicap Chase.
Four horses died in last year's festival. Seven died in 2016.
Buveur D'Air became the first horse since 2005 to retain the Champion Hurdle title by winning by a head in the feature race on Day 1.
The 4-6 favorite gave trainer Nicky Henderson a record seventh victory in the race, but only after battling back after being passed by 7-1 shot Melon on the uphill finish.
Buveur D'Air is the sixth horse to win the Champion Hurdle more than once. The last to win two straight was Hardy Eustace in 2005.
Willie Mullins, Melon's trainer, was denied in that race but finished the opening day with three winners, including Rathvinden -- ridden by his son, Patrick -- in the National Hunt Chase.
The four-day festival is the highlight of the jumps season in British horse racing, culminating in the Gold Cup on Friday.