Locking Stifles

Grooming before ride, noticed my 15 yr gelding seemed to not be fully weight baring on right hind. Appears to walk and trot fine. Asked him to step back, left hind he picks up normally, right hind he doesn’t – slides it back. I don’t feel any swelling or heat in that leg. I am wondering where the problem is, my next steps…

If your gelding seemed totally fine while being ridden, and did not show the same awkwardness on the right hind after you were finished your ride, I wouldn’t get too worried about this yet. Horses can effectively lock their stifles so they can relax and doze while standing up. Sometimes that system malfunctions temporarily, resulting in a leg that can’t flex right away when the horse tries to move. It’s possible that he was dozing a bit on the cross-ties and had trouble unlocking the stifle on that side when you tried to back him up. Fortunately it’s not painful and once the ligament releases it’s business as usual. Keep an eye on him, if this continues to happen or he starts to feel off under saddle then I would call your vet to take a look in case something else is going on.