A filly is a young female horse under four years old. In thoroughbred horse racing specifically, some jurisdictions like the United Kingdom and United States set the cutoff age for fillies as five years old.
Age Distinctions
The horse terminology system follows specific age and gender classifications:
- Foal: Any baby horse under one year old, regardless of gender
- Filly: Female horse from one year old up to four years old (or five in racing)
- Colt: Male horse from one year old up to four years old
- Mare: Female horse four years old and older
- Stallion: Mature breeding male horse
Racing Readiness
Fillies can begin racing as early as two years old. Their strong body structure and rapid growth make them suitable for racing at this young age. They often show considerable improvement as they progress from two-year-old contests through their three-year-old seasons.
Competitive Advantages
Fillies are known for being:
- Intelligent, gentle, and loving despite their young age
- Sensitive and responsive to their environments
- Early developers who reach full height before colts
- Generally having longer lifespans than male horses