As requested in the original posting on "sick horses," I responded directly
to the originator of the posting. I suggested (very tentatively) that the
primary toxicity seemed to be to the kidney. I suggested two possible
mechanisms: 1. Based on the severe reduction in urine volume, I thought that
there might be some agent in the food which is crystalizing in the tubules
creating a physical blockage (e.g., ethylene glycol, which could also produce
some of the CNS symptoms being reported), or 2. Based on the problems with
joints, tubular toxicity affecting the reabsorption of Ca (perhaps a heavy
metal (Cd?) in the feed).
I would be very interested to hear what others in the toxicology newsgroup
made of that posting.