Sore ribs?

Yesterday while tightening my horses girth he nearly buckled over at the knees. He isn’t normally girthy and I tighten up one whole at a time. It was going to the final hole where the girth has always gone when it happened. I also thought I heard a popping sound but was freaked out by the incident so can’t be 100% sure.

After talking with a few people and researching I read that the vagus nerve can sometimes be “pinched” while girthing up and some horses respond like mine did. With that in mind today I didn’t tighten to the final hole. I thought I would try gently stretching his front legs to make sure the girth was comfortable. Right leg no issues, but when I stretched the left leg there was definitely a pop and he kinda grunted. I almost felt like I did a chiropractic adjustment. I rode him at the walk first with no issues and lightly trotted and cantered and he was awesome, forward and happy so I’m confused. There is no heat or swelling anywhere on him, and he isn’t lame. There have been no turnout incidents or any other accidents that would have caused this issue? Ive read differing opinions as to whether a horses ribs actually need a chiropractic adjustment. Any other ideas?

Wow. I don’t know what it is, but I sure would suspect a cracked rib until the vet said otherwise. I don’t think I could tighten a girth on a horse who acted like that uncharacteristically and made a pop. Much less ride it. But hey, good for you. Obviously you don’t think you should call a vet, or you would have. However, I sure would.