Recently, my mare (13 yo) reared on me twice, right after I had started riding in an indoor arena. She's never done this before, and we've had her about 3-4 years, and ridden her quite a bit (trail riding, parades, arena, etc.), with no issues.
I ride with a dressage saddle, but the girth is a bit farther back (it's not directly behind the legs). It's more situated over the rib cage. I'm trying to find a specially fit girth that would suit her better. She acts cinchy, but not anymore than if I had put the girth right where a western style one would be. I've been riding her with this specific girth placement for a little over a month, and I've had no issues whatsoever.
Someone else was using the arena beforehand, so I lunged my mare just a little bit outside. I usually lunge her for at least 10 minutes before getting on, just this was more like 5 minutes of light lunge work. I always tighten up her cinch bit by bit, as she likes to puff out. I took the opportunity to tighten it after lunging her, and used the same hole that I always do (which she's never had problems with). It isn't overly tight, but my saddle doesn't slip, either. When I tightened it up outside, she didn't pin her ears back, and act po'ed, like she usually does, as she was distracted by something else.
It all happened right after I'd gotten on. She wanted to do a little jog after we moved off from the mounting block, and I just wanted to get settled in and have her walk around the arena a few times. I got her to walking, but halfway around the arena she started up that little jog again, and I gently pulled back the reins and sat heavy in the saddle. I was truly being very soft with the reins; gently pulling back and slightly downward with just a little pressure. She tossed her head, then reared twice. Needless to say, I hung on well until she spun around, and that got me unbalanced, and I made a split second decision to bail before she decided to do anything more crazy.
We then lunged her for 20 minutes or so, to evaluate her movement and behavior, and I got right back on for half an hour. She didn't act badly at all during that time, but we had moved the cinch up towards her elbow a bit.
I'm riding her in a snaffle bit, which I've been riding her with for over a month as well. Nothing about her tack has changed. We added a half pad and riser to the mix a couple weeks ago, but that has improved her behavior overall.
We originally thought that this was behavioral, but now I'm not so sure. When we went out to check on her today, I felt along the underside of her belly, where the ribcage starts and makes a "V". It felt like there might be a small upraised welt right where the cinch had sat, so I pressed it firmly, but not roughly. She inhaled sharply, her head went straight up, ears went back, and she tensed, then walked off.
I'm wondering- does this sound like a fractured or possibly broken rib? I have no idea when she could have gotten such a thing. I had ridden her the night before the rearing incident, and we had gotten along perfectly. In fact, she was so calm and relaxed, I was impressed with her behavior. She wasn't turned out at all the day that the incident occurred, but she has a big run to walk/jog out into.
Opinions? I don't really have the money to get it X-rayed by the vet. If it's a broken or fractured rib, it'll just have to heal on its own anyway. But when I had someone hold her, and felt around that same area, she didn't react at all, although she was a bit tense.
If this sounds like a rib issue, how long could it take to heal? Moving the cinch towards her elbow didn't yield any negative responses from her. I might be compromising her shoulder movement, as she has high withers, but it might help a bit.