Before the Civil War, writes William H. P. Robertson in his landmark The History of Thoroughbred Racing in America, the universal birthday for Thoroughbreds was May 1. After the war, most of the country followed Great Britain’s example and moved the date to January 1. “For many years the South clung stubbornly to the old May 1 birthday, which was something of a paradox, since the earlier birthday was advantageous to warmer climates,” writes Robertson.

Now, all lingering regional differences are settled, and it’s January 1 for all Thoroughbreds born in the Northern hemisphere. That’s not actually when they were all foaled, though. Man o’ War, for example, was born on March 29, 1917; Secretariat’s birthday was March 30, 1970; Silver Charm was born on February 22 of 1994; and Barbaro on April 29, 2003.

In 1918, Willis Sharpe Kilmer commemorated January 1 by hosting a birthday party celebrating Sun Briar, his champion 2-year-old, turning 3 and becoming Derby-eligible. The colt lived at his namesake farm–Sun Briar Court–which the Brooklyn Daily Eagle referred to as a “Million Dollar ‘Horse Haven.'” Kilmer, as W. C. Vreeland wrote in that article, had “so many millions” that he could feel “‘clubby’ in even in the presence of John D. Rockefeller.” He imported bluegrass and lime water from Kentucky and built an indoor quarter-mile track inside his 100-stall stables so that his horses could be exercised even in the harsh upstate New York winters. For Sun Briar’s party, according to the Daily Racing Form, several hundred citizens of Binghamton came to an open house and “visited the Court to pay homage to the great son of Sundridge.” They also toured the indoor track, looked at photographs of Sun Briar’s triumphant 2-year-old year, and viewed Sun Briar ephemera such as the shoes he wore winning the Hopeful Stakes and a crop that had only had to touch his flank one time. (Once, a dinner given for Kilmer featured dancing girls dressed in jockey’s silks. Kilmer clearly loved a party.)

Other owners don’t celebrate on New Year’s Day but on their horses’ actual foaling dates. Man o’ War’s 21st birthday was a national event. Samuel Riddle told the New York Times, “We have the Governor of Kentucky here, the Mayor of Lexington, and twenty-one electric lights on a big cake.” The Mayor called Man o’ War “Kentucky’s first citizen,” and the speeches were broadcast on NBC. Man o’ War ate an equine-palatable cake prepared by cooks at Suffolk Downs racetrack and also enjoyed a “bouquet” of corn and carrots.

In May of 1945, Kilmer’s widow held a 30th birthday party for Exterminator, the 1918 Derby winner and 1922 Horse of the Year who went on to become racing’s best-loved champion. Just as Kilmer had done so many years before for Sun Briar, she held an open house party and invited all the local schoolchildren who loved to visit the retired racer. The cake was made of a soft oat mash, with carrots for candles. Exterminator ate all of it, and his constant companion, a Shetland pony named Peanuts, consumed a miniature duplicate of “Old Bones'” cake. Exterminator died later that year. (Two years before, the New York Times noted the birthday of a non-racing but equine celebrity nonetheless: Roy Rogers’ Trigger turned seven, and celebrated his birthday in the Plantation Room of the Hotel Dixie.)

In 2007, the Kentucky Horse Park held a 32nd birthday party for John Henry. Although the 1981 and 1982 Horse of the Year was feeling “unsociable,” as Kelly McAninch wrote in the Thoroughbred Times, fans visited, reminisced about the old man, and admired his longevity. One devotee sent the same peppermints-and-roses wreath as in previous years.

Even when a horse is gone, his birthday can remain a holiday. Just this past March, people celebrated Secretariat’s birthday (his 42nd) at his birthplace, the Meadow, in Doswell, Virginia. In the wake of the movie about Red’s life, there was a contest for Secretariat look-a-likes and the 1973 Triple Crown races showing on a loop. Rainaway, Secretariat’s grandson, reminded partygoers of his great ancestor.

Along with these specific festivities for racing’s stars, some horse people (most likely the same kind people who invite every child in the class to a kindergartner’s birthday party) keep celebrations fair and consistent: On January 1 of 1921, James Coffroth, the president of the Tijuana racetrack, gave one pound of lump sugar to each of the eight hundred racehorses stabled there.

In that spirit, happy birthday to all Thoroughbreds.