symptom of several unrelated animal diseases, in which the affected animal walks with an unsteady, staggering gait and seems to be blind. The many possible causes include poisoning from ingesting plants containing a high level of selenium or from ingesting grasses infected with the fungal disease known as ergot. Magnesium or calcium deficiency may also cause blind staggers, as may inflammation of the brain (encephalitis) or of the brain coverings (meningitis).