*Waiting for more epxperienced people to answer.
How much and what kind of experience do you have on with working with horses?
I bought my gelding (10yo ISHxHolsteiner) just over three months ago. We are still having some challenges establishing roles, boundaries, and manners, and I am finding it a bit of a challenge.
This will always happen and continue to happen, whether you have owned the horse for three days, three months, three years, or even three decades. All horses test if you are their leader. Hopefully, once things become a little more established, the tests become smaller and less often, but it is not a "set it and forget it" thing.
Over time, I think his rude behavior is getting worse.
If it is getting worse, then something is making it worse. When something changes, the horse changes because horses are masters at adaptation. That change can be for better or for worse.
To start, he had a five-stage PPE (all fine), master saddle fitter come to fit my saddle for him, teeth done, back done, feet in good condition and regularly cared-for. I haven't seen any signs of ulcers, lameness, or pain. He was a touch unfit when he arrived but nothing too bad. He's kept at a very nice full livery yard, has daily turnout, regular exercise which I do my best to keep varied, etc. (in other words, he has a pretty good life).
That is good that you are trying to rule out physical problems.
I was told he tends toward the lazy, which was certainly the case at first although over the months I have gotten him a bit more forward in general. However, I know work is not his favorite thing.
Although many horses tend to be on the energy conservation side of things, I don't believe that horses are truly "lazy." A lazy horse is a dead horse. Horses know this. If the horse is "lazy", they find no motivation to move forward/eagerly.
Horses are also feeders. You have to want the horse to go and raise your own energy levels.
Since the first week I've had him, he has refused to walk toward our riding arenas and/or refused to walk up to the mounting block. Plants all four feet, head in the air type business. Sometimes a "walk on" or a few gentle taps of a schooling whip are enough; other times this turns into a big refusal, where he'll keep backing up to avoid going forward. I had thought that just calmly getting on with it would eventually break him of this habit, but the protests have been consistent if not worsening of late. Once you are on him, he is sometimes a little lazy but otherwise a good ride in the school (hacking another story). However, this is I think a symptom rather than a problem on its own...
It is hard to say whether this is just plain testing or a physical problem. It could be either or it could be both.
When you say "hacking", do you mean trails? Some horses just aren't cut out to be arena horses and will balk/become very arena sour.
Perhaps he has a bad incident in the arena? My horse slipped and fell, hard, in the arena while I was ridding her, so she is a little anti-arena. Though, she doesn't behave like your gelding...
I have tried to do some groundwork with him to establish rules and manners, but this is ultimately where I think the rub happens: He thinks he's in charge, and I can't seem to disabuse him of this notion. The more I try to get him to move his feet, yield to pressure, and encourage manners, the more he seems to fight it.
Do you know this horse's history?
What do you plan to do with him?
Once the horse gets the basics, I tend to do groundwork "on the fly." Instead of having specific, time-set sessions, I just direct and/or correct as needed (This is groundwork "for respect" rather than teaching a specific movement, such as side-passing).
My horse is kind of like this, in terms of not liking groundwork. The more I try to "establish myself as the leader", the more she protests. That's is understandable. If you watch horses in a herd, once some stuff has been established, they don't have specific "I am the leader" sessions. They sometimes push as a reminder, but otherwise do most of it on the fly.
Horses do not like to be nagged.
He has gotten increasingly bratty about these things: for example, my recent efforts to get him to be more attuned to my personal space and move him around in his stall while I'm grooming him have been met with greater irritated tail-swishing, pulling faces or threatening to nip at me, turning his hindquarters to me, or just refusing to move.
Funny (or ironic) that you should mention that.
Usually, horses are a reflection of you (or treatment).
For a stalled horse, their personal space is their stall. I am not excusing his behavior even in the slightest, but you guys had the exact same thought about whose personal space.
I think that a horse should let you do what you need to do in their space, but if I can help it, I do like to show some respect. How is he when you take him to a "neutral" space, such as the barn isle or under a tree?
On a recent afternoon, I decided to take a detour while leading him from his field into the barn -- I'm certain he was of the opinion it was feeding time (it was not, in fact) and when he pulled the "I refuse to walk where you are leading me" routine and got the spinning end of a lead rope toward his bum in return, he turned tail, kicked out several times (kicking me in the process), and ran off -- this happened twice that day. He will occasionally do the same if being lunged.
Ouch! I hope you are okay.
He learned that by balking and kicking out, he gets release and to go where he wants. That's not good.
I have done what you did and my horse did what yours did (except the actual kicking me and running away part). She refused to move. I was like, "Okay, if you don't want to move forward, you'll move in one way or another" I disengaged her hindquarters with the end of lead rope and she kicked out at me. This was a long (many years) ago, but before that she had never kicked out at me or even thought about it. I have come to the conclusion that she did what she did because I was being rude. She was unsure about whether to go or not and was nervous, then I just hit her with the rope. Sure, it would be ideal that the horse would always follows you willingly, but they are not machines. For her, the best thing is to just keep pressure on the lead and halter (not pulling), wait, and release once she comes forward. She very rarely balks now, but when she does, I only have to wait less than three seconds before she decides to come. This won't work on every (or most) horses, especially if they don't know how to give to pressure. Some horses will think of it as a poll massage and stand there forever. The thing is, for some situations and for some horses, simply out-waiting them works.
This is the barn that he has been in many times, yes?
So, this is all annoying but seems like it would be fixed with simple groundwork exercises. However, I can't seem to get those to be useful (at least not so far). He gets immediately frustrated about this kind of training, and either resorts to backing up to try to evade the exercise, threatening to nip at my hand that's on the lead rope, or both. If I attempt to escalate by using a stick or giving the lead rope a yank, it ticks him off more, and things continue to deteriorate.
Again, some horses just dislike groundwork. As counterintuitive as it sounds, he may not need all of this "aggressive" groundwork. If not, he may be saying, "Why are we doing this?"
I had a word with a prior owner, and while I didn't go into too much detail about his behavior, she said that he "likes to be asked nicely" and that he does not respond well to being told what to do. Well, that's nice if he does what you ask when you ask nicely, but half the time he doesn't want to say "yes" to what he's asked, so then what? And who's in charge of whom in that situation? So I gather this is partially a horse who is used to getting his way, and who is fighting giving up the leadership role.
While babying a horse is not good, for some horses, you really do need to ask nicely because telling them does not work.
When you were a kid, have you ever thought it'd be nice to do a chore (the dishes, for example) without being asked? Then, two seconds before you do it, you're told to do it? Oddly specific example, but if you had, you know how it feels. It is a feeling that is hard to describe, but it takes away that "want", that drive. I think that the same goes for some horses. I don't know. I may just be anthropomorphizing.
But, I can't tell if this is acting out because I'm putting slightly more pressure on him to behave himself, or if this could be a pain/health issue I've not caught onto, if this is winter boredom from too little grass/too much mud/too little daylight, or what.
It could be....
Has anything else changed?
I have a natural horsemanship trainer coming out in a week and I hope that will help, but was curious what others would do if they were in my shoes. Does this just sound like a horse who needs to learn manners? Do you think there's something else going on?
It is good that you have someone comming out.
It is actually really hard to say what he is doing and why, especially without seeing him and you working together.