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Re: [RC] Selenium again - Heidi SmithWhole blood analysis is what my vet has done (at >Cornell, except for thetime their equipment was on the >fritz and it went to Michigan). Yup, I stand corrected. My copy of Diagnostic Techniques in Equine Medicine says whole (heparinized) blood, not serum. FWIW, it also says it takes about 5-6 weeks for changes in selenium uptake to be evident via blood tests. I'm assuming that refers mostly to oral supplementation, prolly not so much via IM injections, but don't know for sure. I had the opportunity to run serial tests on about 40 purebred Red Angus calves several years ago, all of which were out of cows that had not had prenatal selenium, and all of which had an injection of Bo-Se within 24 hours of birth. In that group, I found that the maximum level of whole blood selenium occurred at about 2 weeks post-injection, and then declined gradually over the next 4 weeks until by 6 weeks, they were just as deficient as the herd baseline. I do suspect that oral supplementation takes longer. I've tested several horses over the space of several months that were REALLY deficient, many never did get any increase in selenium level from oral supplementation. But once given an injectable dose to get the levels up to some degree, they would be able to maintain just fine on oral supplementation. Just my own theory--absolutely no testing done to substantiate this--given the role that selenium plays in cell membrane function in other types of body cells, I suspect that the EXTREMELY deficient horse has sufficiently poor absorptive capacity in the GI tract that he CAN'T absorb the selenium that is there, even when it is present in the diet in "adequate" amounts. Perhaps megadosing would have worked, but I wasn't brave enough to try that. Heidi Heidi =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= 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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