Neurologic disease in range goats associated with Oxytropis sericea (locoweed) poisoning and water deprivation

About 200/2500 Spanish goats foraging on mountain rangelands of western Mon tana developed neurologic disease with severe rear limb weakness, knuckling of the rear fetlocks, and a hopping gait. Sick goats were of all ages and in good flesh, though they often had dull, shaggy coats. Some mildly affect ed animals recovered after being moved to feed lots, but others progressed to recumbency. seizures and death. At necropsy both moribund and clinically affected animals had few gross lesions; I animal had contusions and punctu re wounds on rear legs and perineum, suggestive of predator bites. Histolog ic lesions included mild vacuolation of neurons and visceral epithelial cel ls, mild diffuse cerebral edema with minimal neuronal pyknosis, and random, multifocal Wallarian degeneration of spinal cord axons, Affected animals h ad elevated serum sodium, potassium and chloride levels: other mineral anal yses and serum biochemistries were within normal limits. Locoweed-induced d epression and inhibition of neuromuscular function coupled with water depri vation due to predation pressure allowed development of neurologic disease and hypernatremia.