COOPERATIVE KENTUCKY STATE UNIVERSITY FACT SHEET

Information about the Kentucky State University Cooperative Extension Program 2020

Dr. Jerusha (Jessie) Lay, Assistant Professor of Animal Health

Polioencephalomalacia (PEM) is a relatively common disease in small ruminants. It is also referred to as “star gazing disease” or “polio.” PEM manifest itself as neurologic symptoms but it is actually a nutritional disease. It is caused by decreased thiamine (vitamin B1) to the brain. The brain tissues have high energy demands and thiamine is needed for glucose to function in the brain tissues. The result of low thiamine levels is cerebrocortical necrosis (dying brain tissue).

One of several functions of a healthy rumen is B vitamin synthesis. In normal adult ruminants, the microbes in the rumen should make enough thiamine for the animal. PEM may be caused by the lack of thiamine, or in other cases there may be enzymes that are destroying thiamine or other substances that affect the function of thiamine.

When kids/lambs are first born, their rumens are not developed yet and B vitamins, like thiamine, need to be provided in the diet. This can be one reason polio is more common in younger animals. If an adult animal is not eating or if its rumen has a severe acidosis to where the microbes die or there are sudden changes in the microbe population, the digestive upset may cause PEM.

Thiaminase is an enzyme that breaks down thiamine in the animal's system. It may be ingested from certain plants or released by gut bacteria in certain conditions. Diets high in sulfur interfere with the function of thiamine. Diets that are high in commercial byproducts or certain oil seed mills contain high sulfur content. Byproducts such as distillers grains can also be high in sulfur. Distillers grains should not exceed 30% of a ration and each batch of distillers grains may widely vary in sulfur content, so some batches of feed may be higher. Plants or forages that occasionally have high levels of sulfur or affect thiamine levels are alfalfa, Canada thistle, Kochia, lambquarter or cruciferous plants like turnips, and mustards or oil seed meals. In some areas, water sources may have higher sulfur contents as well.

contain high sulfur content. Byproducts such as distillers grains can also be high in sulfur. Distillers grains should not exceed 30% of a ration and each batch of distillers grains may widely vary in sulfur content, so some batches of feed may be higher. Plants or forages that occasionally have high levels of sulfur or affect thiamine levels are alfalfa, Canada thistle, Kochia, lambquarter or cruciferous plants like turnips, and mustards or oil seed meals. In some areas, water sources may have higher sulfur contents as well.

Many sheep and goat producers use amprolium (Corid) to treat herd problems with the parasite coccidia. Amprolium may decrease blood thiamine levels. At labeled doses, cases of PEM will happen rarely; however, if animals have other factors such as digestive upset or the presence of amprolium in a water source that evaporates quickly, several animals may be affected. It is still considered a safe product, but animals should be watched closely for symptoms of PEM when treated with amprolium and for a week after treatment.