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When supplements kill: selenium overdose kills 21 horses

  1. Apr 24, 2009 #1
    Conclusion to the polo story. A compounding pharmacy mixed up vitamins and electrolytes for sports horses, but they added 5 mg/mL selenium instead of 0.5 mg/mL, which was the lethal mistake. (It does not say what the total dose was).

    Selenium Overdose Caused Deaths of Polo Horses
    http://scienceblogs.com/grrlscientist/2009/04/selenium_overdose_caused_death.php [Broken]

    For comparison (I looked up), "Centrum Silver" has 55ug Se (0.055 mg), so 5 mg is about 100 tables - most of a bottle.

    http://www.centrum.com/product_detail.aspx?productid=CENTRUMSLVR&panel=tablets [Broken]
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Apr 24, 2009 #2


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    Horses are VERY sensitive to selenium. They need a little bit as an essential mineral, but can easily overdose. The safety margin isn't so bad with humans. I know of one horse farm that had well water and had to get city water brought in for watering the horses, because the well water had too high of a concentration of selenium. It was still safe for people to drink, but too high for the horses.
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