please help.

Where are you located?  We have an amazing trainer here who will give you some great pointers.  Not sure if she will be here this evening or not.  Please keep coming back and hang out when you can!!! 
VERY nice looking gray you have there!  Is that him?  And you?  What's the back problem that's being treated?

um sutton NSW Australia
yea thats me and him at his first hack show.
hes a real idiot when hes in the paddock, he just runs and runs and doesnt stop and he decided to jump one of our fences when he was 3 and pulled alot of the muscle along his spine and neck, he did a realy good job and is still having problems from that

Could the problems he has with his back be causing the cantering refusal? 

it does definatly effect him and his cantering. i.e he can't go into a trot or canter on a circle, if you tryed geting him to do so on a cricle or turn youd most likely fail completely; it hurts him but from what the chiropracter has mentioned he should be perfectly capable of doing his tranistions intocanter on a straight line and then circling. BUt you see i'v been having these same problems scince before he injurded himself. he was nearly 4 when he did this and rising 3 when he was put under saddle and have the same problem from day one. hes a realy lazy horse once hes caught constantly trying to sleep majority of the time when i ask him to trot or canter (this problem is mainly for canter) he just really seems like he couldnt be botherd and just bluntly says no. once hes cantering he seems fine but the tranistions are realy messy. he just pigroots and it has been really dangerous in the past. having put me in hospital aswell as my cousin. but i will defintaly look more into is back problem, cheers
 

I didn't mean to be nosy but you mentioned your aunty from the states.  I've traveled some but never to Australia.  I'd love to, though.  If I do, I'll look you up!!!  And vice versa!

I know diet can play a big part in energy level and overall attitude.  You might consult a nutrition expert about that, just in case.

I rode last weekend and my horse bucked for the first time with me.  He did it several times.  I suspect the saddle, actually.  It was the second time I'd used it with him and even I wasn't very thrilled with it.  I might sell it.  I sure don't want a repeat of last weekend!

I don't know what pigrooting is.  It's a funny phrase but probably not as funny trying to ride a horse that's doing it. [:-]

Hi there welcome to the forum.  If I'm not mistaken when you say "pigrooting" he drops his nose and shakes his head, really doing a little dance on the front end?
 
The first thing I would look at would be his teeth.  If their jaw can't move forward adn back freely then the horse can't lope properly.  Next step would be on the ground to see if I could get him to canter in a 60 or even a 70ft arena although bigger than 60 and you are doing a good bit of running yourself.  Have you done much ground work with him?  The process of elemination might also help to see where his true problems are.  Turn him loose, no tack at all and see how much pressure you have to put on him to get him to canter.  Does he flat out refuse and get snarly or does his ears say pain?  If it is just a fit then I would work on transitions like that for a week.  Take him in and be consistant with cues and enforce those cues such as if you click once he should walk off, click twice or more and he should trot, kiss and he should lope.  When he refuses to move his feet at the pace you decide pour the pressure on and really drive him forward.  Also this is a great oportunity to build a horses muscles.  A lot of endurance, Roping and general riding horses have no clue what leads are and that they are supost to be in one or the other.  If you watch him closely he might go into a canter easier moving to the right or left, the direction he has the most trouble in work him each day about 5 -10 minutes more to help him build those muscles and balance himself out.  If he is equal then try for 5 minutes of trot, 5 minutes lope each direction letting him rest for 5 minutes between.  I would do this until he transitioned smoothly and without panic consistantly.
 
Next add the saddle that you ride in the most.  By now he should have all the cues down pat and know if he doesn't move you will MAKE him move.  If there is a change, it could be that the saddle is pinching somehow making it uncomfortable for him to move.
 
After another 3 days of this as this also helps them learn to canter and balance with the extra weight add the bit you normaly ride in.  Take the reins off and just hang the bridle in his mouth where there is no pressure.  Now go back and do the same routine as before.  Have him move in all three gaits.  If he pitches a fit just push him through it and make him move because if he canters without saddle and with then the bit is not the problem he only thinks it is.  It could be that at some point in his life, depending on his mind set, when cued for a lope the bit was also engaged confusing him or scared him thereby leading him to acossiate the bit with pain of loping.  If this is it then the best thing to do is work him all tacked up with the bridle on and let him find for himself there is no pain to lope.
 
Lastly is to get on and have someone on the ground that knew what you had been doing these past two weeks and how to cue the horse.  You just be passanger and try not to pick up on the bit unless you have to and you cue for each gait, then the ground man enforces driving him forward.  Be realistic though in the beginning don't try and make him canter 6 laps but when he finally breaks into a lope let him stride out say 4 good strides and stop him.  Give him a good pat and let him relaxe for a moment to think on it.  Then do it again, maybe this time get 6 strides and quit for the day.  Each day you can build on it but just let him find how to balance and use himself in the canter.  I like to save the riding for very last till I know they are comfortable, relaxed and understand what is expected.  On the day you were going to try this I would even take him into the arena early and have him move through all the paces once more just reinforcing what he needs to do.  Have your ground man there as well so he knows he has to listen to him before hand, that way during the ride session, there are no surprizes for your horse.
 
This is what I have used in the past for many horses that "Won't Canter" and it has worked for me every time.  Having the ground man is also a plus because it gives the horse something else to focus on instead of just the rider, meaning less association and usually free forward motion so long as you let him move out and really reward him when he does.
 
Hope this gives you some ideas.  Good luck and keep us posted.

Awesome trainer!  I've NEVER heard that about their teeth hindering the canter but I'm pretty consistent about feeding mine at ground level to try to keep their teeth right.  Wow.  That's so interesting!

Its actually really cool Beth to see the skull of a horse and how it worked.  Had an equine dentist at one of the clinics I went to several years back.  He did a demo on how the horses teeth play such a big role in their movement.  Showed the skull and jaw with great teeth and then one with hooks in front and back and along the sides.  He had you place your hand on each side and moved the skull as though in a canter.  The jaw couldn't move forward and back and as it tried to it also rubbed along the palms of your hands.  I was amazed at how quickly I wanted to move my hand away because of the discomfort.  Think of that and then add the bit pressure along the cheek pressing in slightly.  Can you imagine how frustrating that would be!  Even if they lope in the pasture its not the same as when you are on asking for them to move in a more collected frame.  It was super interesting.  I love getting that kind of info and hands on demos like that.  Came home and checked Shadow's teeth, he had hooks in front and after having them removed I did the same thing I described above and low and behold here came this perfectly relaxed lope where as before his eyes would get huge and he would act like it scared him to death. 

That's really amazing.  Dental stuff is important.  Too bad it's so expensive!

Dani needs wolf teeth out, I'm sure, although I tried to see them and nothing really jumped out at me.  I'm not sure I'm looking in the right place.  I got the right end of the horse anyway!

haha pigrooting is actualy when they kinda do little bucks. not usually too dangerous but realy fustrating

and thanks for the tips. ill defintaly give it a go. we do do a fair bit of ground work and he seems fine with it, although to much and he starts getting pissed off. he doesnt seem to be in anypain when i ask to canter nor does he get narly. more like. ever had an argument with a teen who does not wanna do somthing. and it just never ends? he sorta gets like that. only if he rrealy doesnt wanna do it he'll buck me off. once he just droped and layd down and tryed to roll me off. hes realy stubborn and pigheaded, probly an arab trait. his sir (who i also own) was like this a bit to. only a little more willing. every bad manner you fixed hed find a way to do somthing else

OHHH!!!!  Zag did that to me all last trailride!!!  Another name is crow-hopping.  []