Selenium Toxicity

The following information regarding Selenium Toxicity has been taken from the National Research Council Nutrient Requirements of Horses, Fifth Revised Ed.

 

The maximal tolerable level of selenium in horses is estimated at 2 mg/kg of diet (NRC, 1980), and the LD50 for orally administered selenium is considered to be approximately 3.3 mg of selenium (as sodium selenite)/kg of body weight (Miller and Williams, 1940). Copper pretreatment can increase the LD50 markedly (Stowe, 1980).

Acute selenium toxicity--blind staggers--is characterized by apparent blindness, head pressing, perspiration, abdominal pain, colic, diarrhea, increased heart and respiration rates, and lethargy (Rosenfeld and Beath, 1964).

Chronic selenium toxicity-alkali disease-is characterized by alopecia, especially about the mane and tail, as well as cracking of the hooves around the coronary band (Rosenfeld and Beath, 1964; Traub-Dargatz and Hamar, 1986).

There are anecdotal accounts of immediate death after administration of injectable vitamin E/selenium preparations. These deaths appear due to an anaphylactoid sensitivity of the horse to a carrier ingredient in the injectable preparations and not to the toxicity of selenium or vitamin E.

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