Pie is doing well since coming off grass - although he's not happy being separated from his herd - his feet are cool and he looks pretty sound and his muscles are no longer tight and cramped. Pie will be tested on Monday for his insulin and thyroid levels, as those can affect metabolism and cause foot soreness. Low thyroid, which can be caused by, among other things, certain funguses that proliferate in grasses with low temperatures and profuse rainfall like we've had, can cause metabolic issues that lead to foot soreness. Another possible cause of his stiffness, sweating and muscle cramping could be PSSM - polysaccharide storage myopathy - which is a genetic disease that is a cause of such symptoms in a small but significant percentage of Quarter Horses. Tying up type symptoms can be caused by many different things in different horse breeds, but PSSM is a particular issue in Quarter Horses, apparently in three undisclosed bloodlines - why undisclosed? can someone explain to me why a breed would conceal information like this? Here is a very interesting case study of a QH with PSSM.
There is now apparently a blood or hair root test for this - see this information from the University of Minnesota - a muscle biopsy isn't necessary to test for PSSM, but if it comes back negative a muscle biopsy may still be required. The good news is that PSSM can be treated in most horses that have it - a combination of a higher fat diet - rice bran, flax seed and additional oils - cocosoya, which we already use, and L-Carnitine, which is needed for the transport of fatty acids within cells.
I'm hoping we have some answers soon to Pie's issues.