Polioencephalomalacia (PEM)

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Polioencephalomalacia (PEM)

Polioencephalomalacia is a neurologic disease of goats associated with severe metabolic imbalances.  Though most often seen in fast-growing kids and young adult goats, it can affect animals of any age.


  • There are several causes for Polioencephalomalacia, including thiamine deficiency, sulfur toxicity, lead toxicity, sodium poisoning, and water deprivation.
  • The most commonly seen cause is thiamine (vitamin B1) deficiency.  Animals that are fed higher levels of concentrated rations can develop changes in the rumen pH, which can lead to ruminal acidosis.  The number of thiamine producing bacteria decreases, while the numbers of thiamine destroying bacteria increases.  Certain medications can also contribute to decreased thiamine levels.


  • Loss of appetite
  • Depression
  • No fever
  • Normal or slightly reduced rumen motility with Polioencephalomalacia
  • Nervous system signs are: head pressing, grinding of teeth, aimless wandering, blindness, abnormal eye movements, muscle tremors, and overreaction or jumping when touched.
  • When the goat is unable to stand, the head usually will pull back. Convulsions and death follow in a few hours.


  • PEM has been associated with two types of dietary risks: altered thiamine status and high sulfur intake. Thiamine inadequacy in animals with PEM has been suggested by several types of observations, including decreased concentrations of thiamine in tissues or blood and deficiency-induced alterations of thiamine-dependent biochemical processes (decreased blood transketolase activity, increased thiamine pyrophosphate effect on transketolase, and increased serum lactate). Unfortunately, many of these biochemical features of altered thiamine status are inconsistently observed in cases of PEM, and decreased thiamine status has been observed in diseases other than PEM.


  • Treatment requires thiamine injections of a total of 5 to 10 mg/kg, one-half of the dosage given IV and one-half given IM. Additionally half doses should be given IM every 12 hours until the animal has recovered. If the goat shows little improvement after 2 or 3 days, slaughter should be considered.


  • No preventive measures have been reported.


Source 1:

Thedford, Thomas R. Goat Health Handbook: A Field Guide for Producers with Limited     Veterinary Services. Morrilton, AR: Winrock International, 1983. Print

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