Relationship between sulfur, thiamine and polioencephalomalacia

Abstract

Thiamine deficiency has been classically described as the cause of ruminant polioencephalomalacia (PEM). More recently excess dietary sulfur has been shown to be a major cause of PEM. This paper reviews the relationship between PEM and thiamine metabolism in mature cattle, thiaminase in plants, rumen acidosis and excess dietary sulfur. Signs of PEM caused by lead poisoning, water deprivation-sodium ion toxicity and sulfur toxicosis are clinically and microscopically indistinguishable. Diagnosis of sulfur-induced PEM relies on ruling out other diseases, and demonstrating elevated dietary sulfur intake. Total sulfur intake from both feed and water must be determined when investigating an outbreak of PEM in cattle.