What is a gelding in horse racing?

A gelding is a male horse that has been castrated.

There are two main reasons that owners and trainers decide to geld a horse.

The first is to get a colt that is unruly and headstrong to calm down by reducing the flow of testosterone and other hormones to his brain. The treatment, jokingly referred to as the “ultimate equipment change,” is often effective, which is why handicappers often elevate the chances of horses in their first races after undergoing the surgery.

The second common reason that a racehorse is gelded is to extend its racing career. Gelded horses tend not to develop physically as much as “whole” horses, and the lighter weights mean they are putting less pressure on their legs when they race and can remain sound longer. That is generally only done if the owners feel the horse has no chance of a successful career at stud.