If Funny Cide wins tomorrow's Belmont Stakes, he will become horse racing's first Triple Crown winner since Affirmed in 1978. He would also be the first gelding, or equine eunuch, to earn the honor. What's the point of snipping a thoroughbred's manhood, especially since a gelding has no stud value?
In most cases, gelding is used as an attitude adjuster. Testosterone makes colts behave quite badly, even violently, toward humans and fillies alike. An ungelded colt will bite, rear, kick, or whinny uncontrollably and may have to be isolated from other horses to prevent such behavior. These young male horses also often refuse to obey a trainer's commands. As human survivors of adolescence can attest, a preoccupation with sexual needs tends to diminish concentration.
A large number of racehorses, then, are gelded quite young. According to the Jockey Club, 25.8 percent of thoroughbreds who raced in North America last year were geldings; that figure doesn't include less glamorous quarter horses, which are also frequently castrated. The procedure is typically done within the first year of life, before the horse can develop too many of the aggressive habits of a mature stallion. Owners are careful not to geld too early, though, as such colts may not mature physically.
An equine castrato obviously can't have a post-career job as a stud, but that's not really an issue for most horses. Only a tiny fraction of professional racehorses possess the stellar bloodlines necessary to earn stud fees. For every descendent of Alydar that brings in millions from an Arab sheik, there are scores of horses that could never even show, let alone win, at Delaware Park.
That brings up yet another advantage of gelding—longevity. Thoroughbred superstars, such as the handful that appear in Triple Crown races, retire quite young, often because they're either put out to stud or slow down markedly after the age of 4. Geldings, on the other hand, can run successfully for a few years longer—the legendary John Henry, for example, was still winning races at age 9. No one's quite sure why this is, but many trainers speculate that the castration leads to less bulky—and thus less injury-prone—musculature.
Funny Cide is an exception to the gelding rules, as he was emasculated for health reasons, not behavior modification. As a yearling, he was a "cryptorchid"—that is, one of his testicles never dropped, but rather remained lodged inside his body—and the testicular defect prevented him from walking normally. Had Funny Cide not been gelded, he likely wouldn't have had any racing career whatsoever.
Bonus Explainer: Funny Cide is lucky he wasn't born a half-century ago, or his Triple Crown dream might have been squashed by gelding bias. From 1919 to 1956, horses bereft of testicles were banned from competing at the Belmont Stakes.
Explainer thanks Karyn Malinowski of Rutgers University.