I have noticed while lunging my horse recently that she has not been tracking up at the trot as much as usual.
She easily tracks up at the walk. Her canter looks pretty good in most opinions, except for occasionally switching her leads behind (vet is fairly certain that this is a lack of muscle, not an injury, and his assessment has been supported by the distinct reduction in this tendency as she gets fitter).
The issue seems to be better when I lunge her in a chambon (yes, I have a real one now, and am no longer using a neck stretcher), and worse when she is ridden. It also resolves almost entirely when I lunge while holding a whip instead of a camera, so it’s possible that she simply does not feel like it unless encouraged.
I know a fair number of OTTBs have the “sewing needle” trot under saddle early on, but I’m wondering what I can do to make striding out easier for her, or if this sounds like an issue of pain. Her vet said that her right stifle may be mildly arthritic, but this particular problem seems equilateral. He also said that her SI damage is extremely minimal for an OTTB and is probably not a factor here.