What is a Young Horse Called? What is a Female Horse Called?
A filly is a female horse that is too young to be called a mare. There are two specific definitions in use: In most cases, a filly is a female horse under four years old. In some nations, such as the United Kingdom and the United States, the world of horse racing sets the cutoff age for fillies as five. The filly then becomes a mare after this agreed upon age.