Are horses predator or prey animals? Put simply, they are prey.
Horses are omnivores and mainly eat grass, though they often like apples, carrots, and sugar. They are preyed on mainly by mountain lions, making them a prey animal and since they don't eat any other animals they are not predators.
Humans are predators and dogs and cats are predators, which can sometimes put a bit of division between humans when training horses. The reason I say this is twofold. One: as a predatory animals, humans brains are wired differently than a horse's is. Two: two of the common animals that humans train (or try to train) are dogs and cats. Many humans will then take what they know about training dogs and/or cats and try to apply that knowledge to horses. That is not the correct way to train a horse.
A horse doesn't think you are going to hurt it, it's thinks you are going to kill and eat it. If a horse is afraid, basically everything you do trying to teach it something will be futile and often will just increase a horse's fear. First, you have to approach it as an animal that is afraid that you will need to calm down and show that you are a friend.
Grabbing a horse and saying, "It's okay, you'll be fine," is a horrible way to calm a horse down. It often will make the horse feel trapped and the horse will react poorly. These situations are quite dangerous and humans natural attempts often only escalate this. If a horse is afraid don't push it through a situation or try to grab it, let it calm down on it's own.
Take it one step at a time, take it slowly, and let it work through it's fear on it's own. Bring it just to the edge of it's comfort zone then stop until it calms down. Then take it back to it's comfort zone and pet and congratulate it then take it a little further. Wait until they are calm enough to not care about what they were initially afraid of before taking it away and then bringing it back and bringing it closer. Repeat this process. Let it sniff and explore the thing it's afraid of. How would you like being thrown into a dark hole and having the doors locked behind you? Many horses are. It's a lot easier for horse and human if the horse can explore the trailer, bite the outside of it, sniff around and take it's time, and isn't forced into it.
Some horses are smarter than others, and some will take longer than others. If your horse views you as a lead mare and you seem calm it will calm down a lot faster. However, if it is afraid of you, the first thing you need to do is work through that fear before anything else. Spend time with your horse, pet it, feed it, let it smell you, and discover that you don't desire to eat it. If you can get your horse to stop operating through fear and also to view you as a lead mare (which is more than just not being afraid but you are it's leader), everything else becomes less difficult.
