Is he stalled right now? Is he getting any movement to help gut motility?
I rehabbed one from a body score of, maybe, 2. Midwest, middle of a stiff winter. All was well for about 10 weeks then ended up taking a late night trip to the clinic due to severe colic symptoms- and thanks to the barn staff for acting in my abcense to get him help. I was 6 states away in the days before cell phones and internet.
Diagnosis was severe impaction colic. Vets told me it is common for horses recovering from long term neglect to suffer impaction and severe dehydration a few months into recovery.
They may produce poops but they are incomplete, failure to empty the bowels kills their appetite and most won’t drink. These MUST get enough physical movement to help the gut, stall is the worst place for them.
Even if living outside, most don’t feel well enough to get enough exercise, they need human intervention via hand walk, lunge, hot walker, treadmill or whatever but they have to move. Least an hour.
Sometimes we stall them meaning to help them but, according to this very well respected clinic, might be the worst thing for them.
Just food for thought. And that B12 supplement can help them feel like moving more, I take it and it does for me. Helped my horses that needed a boost too.
Will continue to keep up with this and jingle.