Genetic variation in hydrogen cyanide potential of perennial sorghum evaluated by colorimetry.

Both annual and perennial sorghum biomass serve as important forage for ruminant animals around the world. Unfortunately, sorghum can produce hydrogen cyanide (HCN), which, if occurring in high enough concentrations, can be toxic or lethal to animals that consume it. The objectives of this study were to develop a fast and inexpensive colorimetric assay to measure the hydrogen cyanide potential (HCN-P) as well as to compare this with existing visual assays while assessing the range of variation for HCN-P among perennial and annual sorghum biomass. The HCN-P of 100 sorghum lines derived from an interspecific hybridization program was determined over 2 years (establishment and regrowth) using both visual and colorimetric assays. Visual assessment underestimated the HCN-P and was less accurate than colorimetry. Repeatability for HCN-P across all sampling dates was functionally zero in the visual assessment and low for the colorimetric assay. This was mostly explained by the significant pedigree × year interaction effects and growth stage. Growth stage substantially influenced HCN-P, which should be considered when feeding animals on fresh forage.

Phosphine intoxication following oral exposure of horses to aluminum phosphide-treated feed.

CASE DESCRIPTION: 66 horses were potentially exposed to phosphine (a gas) 14 hours after being fed a pelleted ration treated with aluminum phosphide. CLINICAL FINDINGS: 28 horses had clinical signs of profuse sweating, tachycardia, tachypnea, pyrexia, ataxia, seizures, and widespread muscle tremors. Clinically relevant laboratory findings included hypoglycemia and high plasma concentrations of lactate and ammonia and activities of gamma-glutamyl transpeptidase, aspartate aminotransferase, and alkaline phosphatase. At least 4 horses had signs consistent with hepatic encephalopathy. Necropsy findings included petechial and ecchymotic hemorrhages in multiple organs, widespread vascular congestion, hepatic lipidosis, and neuronal necrosis in the brain. Phosphine was detected in the stomachs of the 3 horses tested. TREATMENT AND OUTCOME: On the farm, horses were treated with gastric lavage followed by administration of di-tri-octahedral smectite, atropine, fluids, and sedatives. Six horses were hospitalized, and lactated Ringer's solution and flunixin meglumine were administered IV. Additionally, 10% dextrose, corn syrup, and di-tri-octahedral smectite were administered PO. Twenty-seven horses died within 2 days after exposure. Two survivors (1 without clinical signs of toxicosis) made a complete recovery. CLINICAL RELEVANCE: Progression of clinical signs in affected horses in this report was rapid, with few treatment options available, leading to a high case fatality rate. Fumigation with aluminum phosphide is commonly performed to eliminate weevils and other insects from stored grains. When appropriate precautions are used during fumigation, risk to livestock is typically minimal.