Having had some issues in this area with one of my horses, I would make absolutely sure that the saddle fits properly. This requires a trained, up to date, professional. Dawn Anderson,of Anderson Equine is one I really have a lot of confidence in.
If distance is not an issue, Natalie Rooney,of Four Star Farm, in Woodland, California is terrific.She is in the Sacramento area. Her training is focused on the personality of the individual horse, considerate of the horse's needs, no gadgets, no cookie cutter approach.
I have a young horse in training with her right now and, to quote Natalie she rides her "like the mare likes to be ridden". The results of this approach are undeniable.
It took me a while to find Natalie, I could not be happier.
Good luck !
Absolutely hands down you need Jose Alejos. See www.josealejos.com and www.equestriancoach.com (Master Horseman recommended by Bernie Traurig and Linda Allen). He starts horses for La Silla in Monterrey, Mexico and for Branscomb Farm in Half Moon Bay, CA and Maplewood Stables (Julie Winkel's barn). He is the modern Ray Hunt and Gene Lewis rolled into one. He has started some for us with excellent results. We had one bucker who was a rescue and he corrected him in just few days and that horse has remained a solid citizen ever since. You will not be disappointed. Jose guarantees his results.
You said you had the vet out and he did chiro and Accu. For what? Was a full lameness exam done? Saddle fitting on youngsters can sometimes be a nightmare. They change as the muscle up and develop. Also since this is a mare, next time vet is out, take a look inside just to rule out issues that could arise there.
She is either in pain or she's just developed a serious bad habit. This is not to be confused with quirky. She has learned that was she does puts an end to work. And if I thought for one second all the bucking I see from my youngsters before they start U/S equated to the same in tack, none of mine would be riding. Get that notion out of your head. That's somewhat excusing why she bucks. I have yet, in all the horses we've started of various breeds, had any of them buck anybody off. Not when we had them or when they left. Including my warmblood/TB cross who is beyond quirky.
Just for clarification, did she do this at the other place? Was she fine for a bit at your place and then started the bucking? When she's bucked you off, is the session then over? I don't know the people mentioned as I'm not in the States but COTH is pretty good at weeding out the good from the bad. At the moment you need to not worry about anything other than getting this sorted. I would leave her completely off until she goes to new trainer. Otherwise behavoir will just be reinforced. I mean what I say about us never having buckers. Not saying they haven't thought about it, it's just never been allowed. Pure instinct from years of having been bucked off in all manners of ways. I'm old now, I don't fly as well as I used to.
COTH, keeping popcorn growers in business for years.
"I need your grace to remind me to find my own." Snow Patrol-Chasing Cars. This line reminds me why I have horses.
From personal experience, having started multiple horses, it is so much easier if you give them more time to grow up. When I first started breeding and training young horse I thought I had to get them going by 3. Now a days, at 3 my horses are just hanging out, growing, and learning nice grown manners, living in a herd condition so they learn how to be a horse. Then at 4 or even 5 I start them. And what at 3 was a test and a struggle becomes easy breezy. I have found the fastest way to ruin a good youngster is to ask too much of it at too young of an age. And in my experience welshes and warmbloods take the longest to grow up.
Some horses are wicked smart and-- assuming she is not in pain-- she may have just learned how to get a rider off so will just repeat the successful move. It really does not sound like she was over worked but-again assuming she is not in pain-- she needs someone that can consistently stay on her and keep her moving forward when she does her "move."
(I confess, I once used a pelham on that type--just so I could keep the head up and not get bucked off-he learned that dropping the head between his knees would cause the curb to tighten without me having to move my hands-otherwise he was on the snaffle part-- so he in effect was doing it to himself and stopped it. )
Agree with Snowfox! Many at 3 are just not ready mentally to learn in the extended way that daily training demands. There is a big leap in their mental and physical maturity from 3 to 4 to 5. Their spine is not ossified until 6 or even 7 sometimes so weight carrying before then has some risk. Starting them at 4 or 5 makes it very easy if a bit of groundwork has been completed.
But it sounds from the OP's description that the bucking is a bad habit at this point in time. Horses can smell fear and it sounds like this horse has people backed off.
Honestly...that sounds like a pain reaction. Did you have her back and hocks xrayed?
Assuming that isn't...she does need forward installed in a big way.
At just turning 4--she could still be growing. Some of them, especially mares, get pissy if their balance is off. She is clearly saying she isn't ready to canter in the ring either mentally or physically. Doesn't matter what you expect...or what the vast majority of horses are ready for....it is HER that matters. Pushing or forcing it rarely gets you there any faster. Not meaning you do nothing with her, just change your short term goals and expectations. It is a strength issue as much as anything and it takes time....some quite a bit of time. Personally, I'd send her off to where she is worked outside the ring....maybe even on cattle or fox hunting to keep it interesting. Let her grow up a bit more and get stonger before pushing the cantering in the ring issue. It is easier for them to get forward out of the ring and some are not ready to come into the ring at her age.
** Tact is the ability to tell someone to go to hell in such a way that they look forward to the trip. ~Winston Churchill? **
Send the horse to a cowboy. I had the same problem with my WB (except that I got no canter before the bronc bucking started.)
He was a tough case (boy did I kinow that), so it took 4 months before I was even allowed to ride him.
The cowboy I sent him to specialized in problem horses. He had a 16.2h "pony" horse and Petey had his head tied to the pommel of that horse's saddle. (wrapping the 1" thick rope around the horn so he could always be let loose if there was a problem). No way could he get his head down to buck. No way could he stop when he wanted to. He learned that he was not king and could not make his own rules.
Western riders have an entirely different take on horses and they do not allow misbehaving. Period. Some cowboys will throw the horse and hog tie him and sit on him until he stops struggling. (would never use such a cowboy). Others have a "tie donkey" -- the problem horse is tied to the donkey and has to go where ever the donkey goes. He can only drink when the donkey drinks, he lies down when the donkey lies down. It usually only takes a couple days for the horse to realize that he is not the center of the universe and there are rules he must obey. I would check on a cowboy's methods for the attitude adjustment, and if you agree with them, go with that guy.
The cowboy does not want the owner around during this period, and I did not want to be around. Like sausage, I did not want to know what went into the final product.
But I went from a horse which was unridable to a horse who was a real team player. And as a lovely by product of the training, he knew his leads and bending and lateral work.
If you have definitely ruled out a pain/medical issue then she probably needs a different type of approach then what she is getting now. Much like Lord Helpus, I had a difficult one. A very big, very strong 4 year old gelding. Very old-style and cold-blooded in type and mind. Tons of groundwork, super solid in that regard, never gave anyone a bit of trouble. First time put a leg over him he BLEW UP. Sent him to the person who regularly puts a few months on my horses (one of the best young horse trainers in the country, tons of young horse experience both here and Germany) and every time she got on the horse he either blew up bucking, or bolted with no regard to his personal safety. You could sit on the horse, hang over the horse, put anything on him (we thought it was a fear issue at first) with no issues. Bomb-proof on the ground but dangerous as soon as you put a leg over him. After 3 months of that, we brought him home. Decided to send him to a local amish trainer (before everyone freaks out, he isn't the "typical" amish horse trainer that everyone is always telling horror stories about) who started over in the round pen. We were going to see if he could be a driving horse, b/c it looked like riding wasn't in the cards. And, at the risk of being flamed, euthanasia was a possibility if he wasn't going to be safe doing some type of job. Two weeks later, went to visit him and not only was he driving, but he was W-T-C on a loose rein. A week after that I rode him myself. When we brought him home a month later I continued riding him until he was sold. He turned out to be the quietest, most-broke, bomb-proof horse I've had yet. Traffic, livestock, dogs, farm-equipment,hacking on roads, across country, even by himself he was absolutely safe and solid. Now he's packing an adult amateur around the jumper ring. I don't know what was done to him, nor did I want to know at that point, but it was practically miraculous. And it was, literally, his last chance. Never in my wildest dreams did I think that he would make a riding horse, and it made me eat my words about ever sending a young horse to a "cowboy" type trainer. Sometimes you have to explore other methods.
We have a fabulous guy who breaks ALL of ours, and the accent is always forward. When he says they are ready, our show rider, who loves riding the youngsters and getting in their heads, takes over and takes them as far as the owner wants them to go. Both of these people are exceptional at their jobs. And it all takes place under Junior's supervision.
I would make an appointment with Jochem Schleese myself. Far as I can determine from what you say, this mare finds the saddle blocks her at the canter and won't put up with it. She's gone from refusing to go to now bucking the rider off, because no one understand's what she's trying to say.
Hate to say it, but 99.999% of all riders/trainers/vets/chiropractors have no idea whether a saddle fits or not- and Jochem has done the research and the innovation to determine what does fit.
My 3 year old started to give me the same signs as this mare- thank God I was lucky enough to attend a lecture by JS the next weekend and I then did quite a bit of investigating what he had to offer. I took the plunge and even with a loaner saddler in the interim the results are phenominal. No more issues with my young horse, and my older horse who I was on the verge of retiring because of cascading soundness issues is now going better and sounder every single day- and doing work which he has never been able to do before.
Of course, I was able to change the saddle on my young horse BEFORE he learned to defend himself by rearing and bucking and it became a habit. Your mare is well past that, and you cannot expect that a saddle change will now be a miracle. However, if you do decide that saddle fit is the issue, and correct it, I would simply ride her at the walk and trot until she decides herself to offer more. A small amount of patience at her age is nothing in the long run, and a new saddle is considerably cheaper than sending her somewhere to another "fixer" trainer.
By the way, I utterly disagree that 3 year olds should not be ridden and in work for a variety of reasons. It's much healthier for them to be doing a job for their overall soundness and mental health, and it's considerably easier for the rider to start a coming 3 year old if they are skilled in starting youngsters. My 3 1/2 year old is in full training at an appropriate level for his age, and he just grew another inch this winter, so what? He has learned a ton in the last 7 months under saddle, not just riding things either- he has developed a lot of confidence in himself and me, faced lots of new and unexpected situations, and that is also a large part of training babies. It's not just w/t/c, it's learning about his life as a riding horse, and ultimately, a show horse. It's great for him, as it is for every young horse.
I don't believe in is keeping a horse in a stall, especially youngsters. I have the option of keeping my horses in very large paddocks, together, and it is quite ideal. It is very unfortunate that this is the rarity, and stalls are the usual, because it is like keeping a child in a jail cell to me. For all horses, but especially the youngsters, the ability to buck and roll and walk without the rider keeps them safe under saddle, plus the older horses enforce discipline as well. I'm too old to hit the ground anymore, so why stack the deck in the favor of misbehavior?
I wish you the best with your mare, no matter what you decide.
Without seeing this in person, my gut is saying saddle fit issue since it is just at the canter and you say she is sweet with everything else. I would have an excellent, professional saddle fitter out.
If you have done the above, then it is probably a really-bad-habit.
I am also wondering if she did this to the trainer?