Yes, always have your horse's selenium level tested
-- both before supplementing and periodically thereafter.
I have my gelding tested roughly once a year, and
he's always come out at the low end of the normal range -- despite the fact that
I'm supplementing 4mg a day. But in recent weeks he's been
getting more grain (which has Se added) and *a lot* more vitamin E, so I
may not need to give him so much selenium (I'm thinking that the extra E
may be increasing uptake of the Se). We'll know soon, 'cause the
vet's coming out on Tuesday to draw blood for testing.
Cindy
----- Original Message -----
In
general, selenium deficiency is found in all states west of the Rockies
and most states in the eastern third of the country (except mississipi and
alabama which have high levels of Se). Soil in the northern plains
(dakotas, for example where ?Custers horses lost their hooves) tend to contain
near toxic levels of Selenium.
From what I understand horses do not need a whole lot of this heavy metal
(right next to arsenic in the periodic table). Alot of feeds have
selenium in them. So if your horse is performing well, even in a
deficient area, I wouldn't supplement with out knowing what their blood levels
are. Selenium toxicity can look alot like deficiency so this is a good
example of: 'too much of a good thing CAN be a bad
thing'
