Northern Dancer, one of the greatest thoroughbred stallions in racing history, died yesterday in northeastern Maryland at age 29.

The 1964 Kentucky Derby and Preakness Stakes winner, beset with colic and reported age-related heart problems, was destroyed at 6:15 a.m. at Northview Stallion Station in Chesapeake City. He had shown signs of colic Thursday night, and his condition worsened yesterday.

"Sending him to a {veterinary} clinic or operating on him was out of the question," said Ric Waldman, vice president of thoroughbred operations for Maryland's Windfields Farm, where Northern Dancer had resided for two decades as one of the world's most influential stallions. A private burial was planned at Windfields Farm in Oshawa, Ontario, Northern Dancer's birthplace.

"It was remarkable he beat the odds as long as he did," said Joe Hickey, former general manager of Windfields Farm.

Retired from stud duty in 1987, Northern Dancer left 645 offspring and a legacy respected well beyond North America.

He was the second notable thoroughbred destroyed in two days. Alydar, 15, was put down Thursday in Kentucky after refracturing his right hind leg.

Alydar regularly serviced 90 mares a season. Northern Dancer never had more than 46 in any year, but his sons and daughters, 26 of them champions in Europe and North America, had a total of 143 stakes victories and had won more than $20 million in purses.

In 1965, Northern Dancer began his 22-year stud career at Windfields, which was Maryland's largest and most prestigious horse-breeding farm until it discontinued thoroughbred operations in 1988. As many as 300 horses had lived at the 2,000-acre Cecil County farm, but at the time of dissolution only one remained: Northern Dancer.

Small for a racehorse at slightly under 15 hands (5 feet), Northern Dancer was relentless as a runner. Of 18 races, he won 14 and was second or third in the other four. He was named 3-year-old champion of 1964, his last year of racing.

Northern Dancer gained immediate recognition as a stallion and remained viable at 25, an age most thoroughbreds don't even attain. While thoroughbred stallions average one stakes winner from 40 foals, Northern Dancer had 10 of 21 with his first crop, in 1966.

Four years later, the late owner-breeder E.P. Taylor syndicated 32 shares in Northern Dancer at $75,000 each, putting the horse's value at $2.4 million. His rise as a stallion seemed to parallel that of the throughbred-breeding industry itself, and in 1983 the Maktoum brothers of Dubai paid $10.2 million for Snaafi Dancer, a yearling colt by Northern Dancer. It is the second-highest price ever for a thoroughbred.

Before the 1986 breeding season, Northern Dancer commanded an unheard-of $800,000 for one service, with no assurance of pregnancy or live foal.

Northern Dancer's offspring topped the money list in North America in 1971, and in England four times between 1970 and 1984. Among the stallions Northern Dancer produced were Nijinsky II, Triple Crown winner in England; Sadler's Wells; The Minstrel; Nureyev; Danzig, and Storm Bird. His daughters included Obeah, mother of the late filly champion Go for Wand.

Although Northern Dancer raced only twice on turf, he became the most valued sire of turf horses in the world. His most successful offspring raced or stood in Europe, where grass racing predominates. There, no sire line is more revered.

Of the 28 leading stallions in England and Ireland this year, 12 are sons or grandsons of Northern Dancer, including the top three: Sadler's Wells, Night Shift and Nureyev. Northern Dancer and his sons have sired more than 1,000 stakes winners.