One of the most frustrating problems in differential diagnosis confronting today's feedlot practitioner are those cases in which signs of central nervous system disorders are involved. Three of the more commonly seen central nervous system diseases, Thromboembolic meningoencephalitis (TEM)< polioencephalomalacia, and listeriosis are most likely to find their way into a preliminary diagnosis. Additional considerations would be lead poisoning, rabies, organic insecticide poisoning and brain abscesses.