Instructions
Give your filly plenty of exercise by pasturing her with other young horses so she can run and jump and buck as much as she wants, every day. Pasture her with other fillies and geldings or castrated male horses. Even though she may come into season as a yearling, she is too young to be a mother.
Teach your filly to be handled. You should be able to touch her anywhere, including her teeth and hooves; groom, bathe, fly spray and clip her; and put a blanket, a fly mask or sheet on her. She should tolerate all these activities without nipping or fidgeting. If you must reprimand her, be firm but never angry.
Teach your filly to load if she doesn't know how to. If she is worried about the trailer, do not force her into it. Instead, park the trailer in her paddock and put a little grain just inside the trailer. Gradually move the grain deeper into the trailer until she will go in and eat. When she loads and stands quietly in the trailer, begin taking her for short, pleasant rides.
Teach your filly groundwork. She should walk, trot and canter on command, turn left and right and stop when you stop or you say "whoa." She should back up on command or when you wiggle the lead shank. She should stand without pawing or pulling when tied. She should know how to lunge on the lunge line, but do not exercise her on it: she is too young for such repetitive exercise. Insist she always respect your space.
Bombproof your filly. Expose her to everything you possibly can --- from dogs to construction machinery to yellow school buses. Lead her through creeks, over bridges and make her walk across tarps and past flapping things. Rub her with plastic grocery bags and rain slickers. You can't ride her on trails yet but you can take her for walks and then for hikes, either leading her on foot or ponying her from the horse you are riding.
Teach your filly to accept bridle and bit, saddle pad and finally saddle and girth. Teach her to steady herself under human weight by pulling on the stirrups of the saddle and even leaning upon the saddle for a few seconds. When you briefly sit in the saddle on her second birthday, it should be the natural culmination of everything you have taught her.
How to Care for a Yearling Filly
A yearling filly is a female horse between one and two years old. By the time a filly is a year old, she can be weaned. She needs everything a horse of any age needs: veterinary and hoof care; clean water and good food; a clean, safe place to live; other horses for companionship and a firm, loving human partner. A yearling filly is too young to be ridden, but quite old enough for you to teach to be a good equine citizen.