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United States Department of Agriculture

Agricultural Research Service

Title: Neurologic Disease in Range Goats Associated with Oxytropis Sericea (Locoweed)poisoning and Water Deprivation

Authors
item Stegelmeier, Bryan
item James, Lynn
item Hall, Jeffery - USU
item Mattix, Mark - MONTANA STATE DIAG. LAB

Submitted to: Veterinary and Human Toxicology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 1, 2003
Publication Date: October 20, 2001
Citation: Stegelmeier, B.L., James, L.F., Hall, J.O., Mattix, M.T. 2001. Neurologic disease in range goats associated with oxytropis sericea (locoweed)poisoning and water deprivation. Veterinary and Human Toxicology.

Interpretive Summary: About 200 Spanish goats foraging on the mountain rangelands in western Montana developed severe rear limb weakness, knuckling of the rear fetlocks and a hoping gait. Sick goats were of all ages and in good condition though they often had dull, shaggy coats. Though some mildly affected animals recovered after being moved to feed lots, the disease in others continued to progress as animals became recumbent, developed seizures and several died. At necropsy affected animals had few gross lesions. One of the animals had contusions and puncture wounds over the rear legs and perineum. These lesions were suggestive of predator bites. Microscopic changes found in the tissues of affected goats included mild vacuolation of neurons and other glandular and epithelial cells, mild diffuse cerebral edema with neuron death and axon degeneration. Affected animals had increased serum sodium, potassium and chloride. Mineral analysis and other serum biochemistries were within normal limits. These clinical, histologic and analytic findings suggest both locoweed poisoning and water deprivation or salt poisoning caused this disease. Locoweed induced depression and inhibition of normal neuromuscular function coupled with predation pressure keeping these animals away from water sources probably contributed to these animals developing hypernatremia and neurologic disease.

Technical Abstract: About 200 of 2500 Spanish goats, foraging on the mountain rangelands in western Montana, developed neurologic disease. Affected animals had severe rear limb weakness, knuckling of the rear fetlocks and a hoping gait. Sick goats were of all ages and in good flesh though they often had dull, shaggy coats. Though some mildly affected animals recovered after being moved to feed lots, the disease in others continued to progress as animals became recumbent, developed seizures and several died. At necropsy both moribund and clinically affected animals had few gross lesions. One of the animals had contusions and puncture wounds over the rear legs and perineum. These lesions were suggestive of predator bites. Histologic lesions included mild vacuolation of neurons and visceral epithelial cells, mild diffuse cerebral edema with minimal neuronal pyknosis, and random multifocal Wallarian degeneration of spinal cord axons. Affected animals had increased serum sodium, potassium and chloride. Mineral analysis and other serum biochemistries were within normal limits. These clinical, histologic and analytic findings are consistent with neuropathy due to both locoweed poisoning and water deprivation. Locoweed induced depression and inhibition of normal neuromuscular function coupled with predation pressure keeping these animals away from water sources probably contributed to these animals developing hypernatremia and neurologic disease.

Last Modified: 10/1/2014
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