"We are all shocked and saddened," Bradley Purcell, farm manager, said in a statement. "Pulpit had meant so much to Claiborne Farm, first as a racehorse and later as a stallion. Thankfully, we know his legacy will continue on through his sons and his daughters."
Pulpit had not shown signs of being ill, Purcell said.
Pulpit, who was 18, had been standing at Claiborne for $50,000. His progeny include Tapit, Sky Mesa, Pyro, Ice Box, Stroll and many others.
Pulpit's first crop as a stallion included Dubai Classic winner Essence of Dubai.
Raced by Claiborne, Pulpit won the 1997 Fountain of Youth Stakes and the Blue Grass Stakes. He entered stud in 1998 and has sired 11 Grade 1 stakes winners.
He was A.P. Indy's most successful sire son, Claiborne Farms said on its website.
Pulpit will be buried at Claiborne Farm.