The Collaborative International Dictionary of English v.0.48:

Loco disease \Loco disease\ (Veter.)
   A chronic nervous affection of cattle, horses, and sheep,
   caused by eating the loco weed and characterized by a slow,
   measured gait, high step, glassy eyes with defective vision,
   delirium, and gradual emaciation.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

loco disease
    n 1: a disease of livestock caused by locoweed poisoning;
         characterized by weakness and lack of coordination and
         trembling and partial paralysis [syn: loco disease,
         locoism]