toxins is hydrogen sulfide, a gas compound that will compete with oxygen to bind with red blood cells and eventually enter the brain to disrupt neural activity. Clinical symptoms Clinical signs of PEM are variable depending on the area of the cerebral cortex affected and may include head pressing, dullness, opisthotonos, central blindness, anorexia, muscle tremors, teeth grinding, trismus, salivation, drooling, convulsions, nystagmus, clonic convulsions, and recumbency. Early administration of thiamine may be curative, but if the lesion is more advanced, then surviving animals may remain partially blind and mentally dull. See also Cortical laminar necrosis References External links Polioencephalomalacia: Disease Caused by a Deficiency of Thiamine at tvsp.org http://ag.ansc.purdue.edu/sheep/ansc442/Semprojs/2002/neurological/polio.htm http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/102000.htm Bovine diseases Sheep and goat diseases