What is a filly?

A filly is specifically defined as a young female horse. In equine terminology, the distinction of age and sex is significant, as it helps in the proper classification and understanding of horses. Fillies are typically classified as such until they reach a certain age, usually around three years old, at which point they may be referred to as mares if they have reached maturity.

This term is essential in various equestrian contexts, including breeding, training, and competition, as it informs handlers and riders about the horse's age and sex, both of which can influence health, training needs, and performance capabilities. Understanding these classifications is crucial for anyone involved in the equestrian world, ensuring effective communication and management of the animals.