how were they tied, exactly? I'm also seeing them at a normal length with your feet in them...
You've been given some good advice. Slow down, take it one tiny step at a time. Three year old horses are still immature and over-stimulation is the main cause of disasters with young horses all across the world. Adding side-reins, a cavesson, a saddle, a lunge line, a rider, and a whip to an extremely green horse is like tossing a fifth grader into algebra. They can pretend to understand, but within a very short time- they're overwhelmed and they blow up. In this filly's case- I mean blow up quite literally.
Go back to the beginning. No tack, no lunge line, no side reins, just a halter and lead rope. Baby steps. Does she know how to back on the ground, respond to voice cues, and yield to pressure? If not- start here. You cannot ride a horse that does not understand that pressure is the cue to move, and that movement is the only way to stop the pressure. Teach her to yield to you at the shoulders, at the poll, at the neck, the hindquarters, and at the girth-where your feet will eventually be resting. She should move the moment you touch her after a while, no pressure needed. She knows what to expect and why. She should respond to the verbal 'woah, back, walk, and trot' instantly and obediently. Only then should you move on to something besides leadline work. I teach all of my weanlings and yearlings this from the start, making it fun and rewarding. After all, they're still babies.
Once she has mastered this, move on to just wearing the saddle. Repeat all previouse lessons with the saddle, asking her to yield to pressure. Lunge her at only a walk and trot on a 20-25 ft line, and teach her to change directions as soon as you ask. Make sure she is absolutely comfortable. Desensatize her to the saddle and your lunge line as soon as you're done.
always keep sessions less than 25 minutes long, and reward her with praise, a good scratching, or perhaps a carrot. Lunging should only be 5-10 minutes long.
Next, move on to the bridle. Do not lunge her in the bridle yet. Simply work on leading, giving to pressure on both sides of the mouth, and flexation. Once she is comfortable with this (I'd give it atleast three sessions) and not mouthing at all or showing wariness or hesitation, you can lunge her at a walk and trot with the bridle but no side reins. Draw up your stirrups- do not tie them in any way or form. Do not have both a bridle and a cavesson on at the same time. Pick one and use it. Do not interchange.
Babies thrive on short, meaningful, consistant sessions. Three ten minute sessions will teach her ten times faster than one thirty minute lesson.
I would not attempt to back her at all until you get a trainer, and even then- do it in a safe, enclosed area with few distractions. It'd be best for your trainer to do it the first few times, and please don't do it while she's on a lunge line! The last thing you need is for her to bowl someone over or trip on the line, or get whacked in the face like she did in the picture. No whip should ever be used on a green horse.
Otherwise...I don't really know what to say. Don't make rash decisions, alawys have an experienced handler with you, and don't overestimate your filly's maturity. She may just need another 6 months or a year of being a baby. Horses mature at different ages, just like people. You can't mature a horse by throwing stuff at it. It just comes with time.
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