Do you normally give Chocolate baths, or was this the first time? It sounds like he might have had bad experiences with baths in the past, like he might have had water go into his ears or eyes, and be anxious about it happening again. It's also possible that the hissing sound of water going through the hose might have scared him as it got closer to his ears and louder.
Unfortunately, by turning him into the paddock after this incident, you gave him a reward for misbehaving! Now he believes that rearing up will result in what he wants, ending the horrible bath and getting to be let go in his paddock.
You need to retrain him that baths are a normal part of his work, nothing to be afraid of, and if he behaves politely for a bath, he will enjoy some rewards.
Does he normally stand tied for grooming? Tie him, groom him, run water gently over his front legs and shoulders, give him a treat and let him go. Make sure the water is not too hot or cold, as well.
Every day, do the same, but increase where you squirt the water, little by little. Don't use the hose above his neck, clean his mane and face with a wet sponge, and never let water run into his ears or eyes. Any time he stands calmly for a new place on his body that gets a bath, give him a treat, and any time he seems anxious, reduce the water so it just dribbles out instead of making a hissing sound, and give him a treat. Make sure there's nothing about the bath that seems scary, or any more uncomfortable than standing for normal grooming.
If he rears up, go ahead and take him away from the bath, but make him do hard work at something else, like backing up quickly for a long distance. Don't yell or act alarmed, just stay calm, because this isn't to punish him, just to teach him that choosing to do something else besides having a bath is harder work than standing still for a gentle, non-scary bath. Let him stand and think about it for no more than 5 seconds, then gently lead him back to the bath.
I bet if you keep this up for a week or maybe less, he will be good about getting his bath, as long as you never get water in his eyes or ears, and keep the water running out gently and not hissing. Good luck! Chocolate sounds like such a cutie.
Unfortunately, by turning him into the paddock after this incident, you gave him a reward for misbehaving! Now he believes that rearing up will result in what he wants, ending the horrible bath and getting to be let go in his paddock.
You need to retrain him that baths are a normal part of his work, nothing to be afraid of, and if he behaves politely for a bath, he will enjoy some rewards.
Does he normally stand tied for grooming? Tie him, groom him, run water gently over his front legs and shoulders, give him a treat and let him go. Make sure the water is not too hot or cold, as well.
Every day, do the same, but increase where you squirt the water, little by little. Don't use the hose above his neck, clean his mane and face with a wet sponge, and never let water run into his ears or eyes. Any time he stands calmly for a new place on his body that gets a bath, give him a treat, and any time he seems anxious, reduce the water so it just dribbles out instead of making a hissing sound, and give him a treat. Make sure there's nothing about the bath that seems scary, or any more uncomfortable than standing for normal grooming.
If he rears up, go ahead and take him away from the bath, but make him do hard work at something else, like backing up quickly for a long distance. Don't yell or act alarmed, just stay calm, because this isn't to punish him, just to teach him that choosing to do something else besides having a bath is harder work than standing still for a gentle, non-scary bath. Let him stand and think about it for no more than 5 seconds, then gently lead him back to the bath.
I bet if you keep this up for a week or maybe less, he will be good about getting his bath, as long as you never get water in his eyes or ears, and keep the water running out gently and not hissing. Good luck! Chocolate sounds like such a cutie.