Horses in the Kentucky Derby are Thoroughbred racehorses that are exactly three years old and meet strict eligibility rules.

Quick Scoop: The Basics

  • Breed: Only Thoroughbreds are allowed to run in the Kentucky Derby.
  • Age: All horses must be 3 years old on the day of the race; they only get one shot at the Derby in their lifetime.
  • Sex: Most runners are male (colts and geldings), but fillies (females) are also allowed and have competed historically.
  • Distance type: They must be able to handle a 1¼‑mile (classic distance) dirt race, which favors a blend of speed and stamina.

What “Kind” Means Here

When people ask “what kind of horses run in the Kentucky Derby,” it usually breaks down into a few angles:

  1. Breed
    • Only Thoroughbreds, a breed developed for speed and endurance in flat racing.
 * Other racing breeds like Quarter Horses, Arabians, and Standardbreds do race elsewhere, but **not** in the Derby.
  1. Age & Career Stage
    • All Derby horses are in their 3-year-old season, which is why each crop of contenders is totally new every year.
 * They are typically already graded stakes performers, having run in prep races at 1 mile or more to prove they can handle longer distances.
  1. Style of Runner
    • Front-runners: Horses that break fast and try to control the pace early.
    • Stalkers: Sit just behind the leaders, waiting to pounce in the stretch.
    • Closers: Drop toward the back early and make a big late run.
    • Trainers and jockeys plan strategies around each horse’s preferred running style before the race.

Eligibility & “Derby Type” Horses

To actually make the starting gate, a horse has to be more than just a Thoroughbred:

  • Must be a registered Thoroughbred, foaled and recorded properly, and racing on dirt at elite tracks.
  • Must earn qualifying points in designated Road to the Kentucky Derby prep races; only the top point earners (up to 20 horses, plus a couple of also-eligibles) get in.
  • Typically have pedigrees showing a mix of speed and stamina , often tracing back to classic-distance sires and well-known bloodlines.

Typical Field Makeup (High Level)

  • 20 Thoroughbred 3-year-olds in the starting gate is the traditional target field size.
  • Mostly colts and a few geldings; fillies can run if their connections choose to aim for the Derby instead of (or in addition to) filly-only races.

TL;DR:
The Kentucky Derby is run only by 3‑year‑old Thoroughbred racehorses that have qualified through a points system, usually colts and geldings with classic-distance pedigrees and proven form at top tracks.

Information gathered from public forums or data available on the internet and portrayed here.