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[RC] [RC] selenium toxicity - Alice Yovich - Sherman

I found some info from the archives which might help you to determine if you were even giving enough selenium to be toxic. Of course, it also depends on what the levels were to begin with and what is being ingested from the hay/feed.  Also, found a website with good info here http://www.ruralheritage.com/vet_clinic/selenium.htm . I seem to recall, but can't find it now, that damage from selenium toxicity is irreversible.  Anyone else know about this?
From the archives:
Regarding selenium:
The daily requirement for selenium is 8-10 mg.  The level necessary for
chronic toxicity is 60-90 mg/day over a several week period.  It is a lot
harder to achieve this than a lot of people think, especially for those of us
in deficient areas.  A kg (kilogram) is only 2.2 pounds.  One has to do the
math when one is serving an amount different than the "per kg" or "per pound"
listed on most labels to figure out how much of any one nutrient there is.

Most feeds labeled as "high selenium" still only contain 2 to 2.5 mg per
recommended serving, because that is all that FDA will allow feed
manufacturers to add.  In other words, if you live in a deficient area, one of
these feeds will only provide one-quarter of your horse's daily requirement.
In other words, you have to add considerably more than what these "enhanced"
feeds contain.

Too much selenium can cause problems with losing mane and tail hair, and in
extreme cases, also sloughing of the hoof wall.  Acute high doses at critical
times of pregnancy can cause malformations in the fetus.  However, deficiency
is a far more common scenario.  Deficient horses are less thrifty, more prone
to immune problems, more prone to rhabdomyelitis (tying-up syndrome), and a
whole host of other problems.

Heidi Smith, DVM