Kissing Spine - what made you suspect it?

[findeight]

Let me add that saddle fit is HUGE in Ponies. Most common in under 14h as the saddles simply are too long for the Pony back and the cantle digs into the spine over the loin or just behind it. Particularly with bigger kids who need the bigger seat. Top of the line Large can take that up, small Larges and Mediums with taller kids riding seem the most prone to it. They’ll drop when palpated right under the cantle and display most of that KS symptom list. Lots of stops too but maybe not for every rider.

Sometimes a rider that lands heavily can really aggravate that while a lighter seated rider doesn’t get as much reaction. OP doesn’t mention how big this Pony is and no idea how many Pomies are afflicted with KS but I would sure look at the back of that saddle and the rider, especially if she is a bit big for a Pony , as a cause of that behavior in a Pony.

[findthedistance]

Horse #1: Arrived to me as a reschool, but I just couldn’t make any progress. Girthy, resentful about being tacked, resentful about being blanketed, highly unpredictable under saddle. I had many rides where the goal became “walk one full lap around the arena on the buckle without melting down.” She might start out okay, but it nearly always devolved into head flipping, striking out, leaping straight in the air, getting light in front, running backwards or sideways, etc. I’m embarrassed that it took me a year to go and get a proper diagnosis. She’s also very difficult to fit to a saddle and I was reluctant to pursue anything else when I knew the saddle fit wasn’t good. The chiropractor found her unremarkable and she was NOT reactive to palpation of her back. I tried treatment for a couple years but never got her right, so she’s now retired.

Horse #2: Developed an intermittent bolting issue, usually when asked for a canter transition, occasionally when changing the bend at the trot. Remedial schooling seemed to resolve this. Then he needed to be held at the mounting block. The day he bolted out of the clear blue while trotting along on a loop on the rail is the day I scheduled his trip to the clinic. His films were horrific and he was immediately retired.

Both horses had a period of time off for medical reasons that preceded major issues presenting. Deconditioning can be a tipping point in a horse that was previously able to manage.