Polioencephalomalacia (PEM) is an essential neurologic condition of ruminants that is seen worldwide. Cattle, sheep, goats, deer, and camelids are influenced. The term PEM signifies a lesion with particular gross and microscopic features that are not specific for a certain etiology or pathogenesis. Historically, PEM has actually been related to modified thiamine status, but more recently an association with high sulfur consumption has actually been observed. Other hazardous or metabolic illness (eg, severe lead poisoning, salt toxicosis/water starvation) can lead to PEM also.
The condition is seen sporadically or as a herd episode. In general, younger animals are more often impacted than grownups. Animals on high-concentrate diets are at greater danger, but pastured animals likewise establish PEM. Cattle fed rations with added sulfate to restrict intake or with results of corn or sugar walking cane processing are at higher danger. The patterns of PEM occurrence depend on the etiologic elements included.
PEM has actually been related to 2 types of nutritional dangers: altered thiamine status and high sulfur consumption. Thiamine inadequacy in animals with PEM has been recommended by a number of kinds of observations, including reduced concentrations of thiamine in tissues or blood and deficiency-induced alterations of thiamine-dependent biochemical processes (lowered blood transketolase activity, increased thiamine pyrophosphate effect on transketolase, and enhanced serum lactate). Unfortunately, many of these biochemical features of modified thiamine status are inconsistently observed in cases of PEM, and lowered thiamine status has been observed in illness apart from PEM.