Just curious--does anyone else have or know of horses who routinely cross canter at liberty but are seemingly sound? My horse just had a bone scan and ultrasound to see if anything was amiss, and everything is perfectly normal. She does not do the cross cantering under saddle, although she does have a great deal of difficulty with counter canter. She also does not cross canter on the lunge. But she cross canters about 50% of the time when she is at liberty in the pasture.
I'd never seen this before in other horses that I've had.
My gelding does this as well. He's sound and gets the chiro and a massage every few months and nothing is ever greatly amiss. Every now and again his pelvis is tipped but even after an adjustment/when the chiro says he feels and looks really good he will still do it. Never under saddle though.
My QH came to me so "one sided" she will often change leads to her "preferred side" when I'm not riding her. Line lunging or free lunging, she'll switch her canter leads even just one or two steps on her own. She has never done this when in a small confined area, like the round pen. I never thought of an injury, just assumed it was a little quirk of hers.