http://www.guardian.co.uk/sport/2009/apr/24/polo-horses-cause-death-florida
especially: "The paper, citing anonymous sources, said that the prescription had requested 0.5 mg of sodium selenite per millilitre of horse supplement, but the chemist had mistakenly included 5 mg, or ten times that amount."
0.5 mg/mL is the correct concentration:
http://www.mci-santeanimale.com/upload/produit/document/BIODYL.pdf
The dosing instructions call for 20 ml IV drip every 4-5 days (Biodyl was marketed as a chemoprotective agent). I'm guessing the horses got IM shots (IV would be eliminated too quickly and the shots are administered to boost endurance). The closest data I could find says:
Assume for a second that the horses were sheep. If the LD50 for sodium selenite is 0.7mg Se/kg and an average polo sheep weighs 450 kg, thumbnail calculations give 650 mg Na2SeO4 per dead sheep (and even then, 100% of the dosed horses died). Even at the botched concentration of 5mg per mL, you'd need to compound at least7 14 kg sodium selenite to kill 21 sheep. Assuming the compound isn't mass produced (it isn't), how does 15 30 lbs of excess salt go unnoticed? Wouldn't the potassium in the compound be a more likely culprit? <---Impossible (92 mEQ K/L Biodyl)
especially: "The paper, citing anonymous sources, said that the prescription had requested 0.5 mg of sodium selenite per millilitre of horse supplement, but the chemist had mistakenly included 5 mg, or ten times that amount."
0.5 mg/mL is the correct concentration:
http://www.mci-santeanimale.com/upload/produit/document/BIODYL.pdf
The dosing instructions call for 20 ml IV drip every 4-5 days (Biodyl was marketed as a chemoprotective agent). I'm guessing the horses got IM shots (IV would be eliminated too quickly and the shots are administered to boost endurance). The closest data I could find says:
Acute selenium (Se) toxicosis was evaluated in 20 female crossbred sheep, 8 to 14 mo of age. Five groups of 4 sheep each were given 0.4, 0.6, 0.7, 0.8, or 1.0 mg Se/kg body weight IM. The LD50 for sodium selenite was 0.7 mg Se/kg body weight with a standard error of 0.035 over a 192 hr observation period. The most evident clinical signs were dyspnea and depression. At necropsy, the most consistent lesions in animals which received 0.7, 0.8, and 1.0 mg Se/kg body weight were edematous lungs and pale mottled hearts. Highest tissue Se concentrations in declining order were found in the liver, kidney and heart.
Assume for a second that the horses were sheep. If the LD50 for sodium selenite is 0.7mg Se/kg and an average polo sheep weighs 450 kg, thumbnail calculations give 650 mg Na2SeO4 per dead sheep (and even then, 100% of the dosed horses died). Even at the botched concentration of 5mg per mL, you'd need to compound at least
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