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RE: [RC] where is selenium high/low? - Susan E. Garlinghouse, DVMThis brings up a really good point. We ran into a lot of horses in central Oregon with levels really "bottomed out" that >absolutely WOULD NOT increase their levels even being fed fairly high levels of supplemental selenium. The selenium yeast >was not available then, so the injectable was really the only method we had to get the selenium actually into the blood <stream. Once we GOT these horses to an acceptable whole blood level, they seemed to MAINTAIN just fine on oral products.> I suspect that this is the same thing that Susan is seeing, but she is using a more bioavailable oral product that can't be >so easily just shunted on down the GI tract and into the manure pile. Even so, I gather that she is having to hammer these >horses pretty hard to get the levels up to par in the first place. Another factor that probably played into it was that while the PNW is notoriously low in selenium, So Cal has traditionally been thought of as being 'adequate' in selenium, and horses weren't often even evaluated or treated for deficiencies. Even less so given that the published 'normal' range for Se values is considerably lower than what seems to be optimal for many horses. Given those regional differences, that might be why I rarely have to use injectable selenium to start to get some response from oral dosing, and never had to more than twice in one horse (and the really interesting thing is that that one stubborn horse had originally come down from the Klamath area, virtually on the borders of Oregon). Even when we had deficiency issues, the horses probably never get to the same extremely low levels you'd be likely to see in the PNW, FL and some of the Great Lakes and other extremely deficient regions. I have no scientific proof of this hypothesis, but I always believed (given the known role of selenium as a cofactor in >enzyme functions in cell membranes) that the selenium-deficient cells of the lining of the GI tract were incapable of taking >up the very selenium that they needed, but once they had some on board, they worked just fine at getting it out of the gut. That sounds like a reasonable hypothesis to me. We know there are other failures in GI uptake when the system is starved of that substrate, thus many of the developments in parenteral nutrition under extreme conditions. Susan Garlinghouse, DVM =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Ridecamp is a service of Endurance Net, http://www.endurance.net. Information, Policy, Disclaimer: http://www.endurance.net/Ridecamp Subscribe/Unsubscribe http://www.endurance.net/ridecamp/logon.asp Ride Long and Ride Safe!! =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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