Submitted to: Journal of Applied Toxicology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/19/2004
Publication Date: 9/29/2005
Citation: Soto-Blanci, B., Stegelmeier, B.L., Gorniak, S.L. 2005. Clinical and Pathological Effects of Short-term Cyanide Repeated Dosing to Goats. Journal of Applied Toxicology.
Interpretive Summary: Some plants, such as cassava, sorghum and Cynodon grasses, produce toxic cyanide when ingested by animals. Most poisonings occure when animals eat high doses of plant. These animals die quickly Aware of such poisonings, farmers have adopted management strategies that reduce the dose and increase the duration. However, the effects of such sub-acute and chronic cyanide toxicity are unknown. Association of many different human diseases with chronic cyanide exposure suggests that cyanide may cause many unrecognized problems that are of great importance for livestock kept on pastures containing cyanogenic plants. Prolonged cyanide exposure has been associated with neurological and thyroidal disturbances in both humans and animals. The purpose of this work was to describe the effects of short-term toxicity to goats and compare them with those described in other species. No significant gross lesions were found in any of the necropsied goats. Additionally, no microscopic changes were found in the control goats. In the treated animals histologic changes included minimal vacuolation and swelling of the cells. The kidneys cells also had minimal vacuolation and swelling. The most striking change was that of vacuolation of the brain. In summary, we found that sub-lethal cyanide doses given repeatedly for 7 days cause significant clinical and neurologic lesions. Cyanide exposure is dangerous and is likely to significantly compromise the animal’s health. Additional studies are needed for better characterization of these lesions, to determine how they develop and if the process is reversible.
Technical Abstract: The purpose of this work is to determine and describe the effects of subacute cyanide toxicity to goats. Eight female goats were divided into two groups. The first group of five animals was treated with 8.0mg KCN kg-1 body weight day -1 for seven consecutive days. The second group of three animals was treated with water as controls. Complete physical examination, including observation for behavior changes, was conducted before and after dosing. One treated animal was euthanized immediately after dosing. Later, two of the remaining treated animals and a control goat were euthanized after a 30-day recovery period. Euthanized animals were necropsied and tissues were collected and prepared for histologic studies. Clinical signs in treated goats were transient and included depression and lethargy, mild hyperpnea and hyperthermia, arrhythmias, abundant salivation, vocalizations, expiratory dyspnea, jerky movements and head pressing. Two goats developed convulsions after day 3 of treatment. One animal developed more permanent behavioral changes as she became less dominant and aggressive. Histologic changes included mild hepatocellular vacuolation and degeneration, mild vacuolation and swelling of the proximal convoluted tubules of the kidneys and spongiosis of the white matter (statsu spongiosis) of the cerebral white tracts, internal capsule, cerebellar peduncles, spinal cord and peripheral nerves. In summary, sub-lethal cyanide intoxication in goats resulted in behavioral changes, and during the treatment period animals showed delayed signs of toxicity. Significant histologic lesions in goats were observed and need to be characterized further.