Re: Selenium

[kitten@resp-sci.arizona.edu (Bruce Saul)]

	I have an 8 year old mare who we have been trying to breed for
3 years with only one marginal and brief success this year when she caught
but at 20 to 21 days got strangles (the variety some of you guys are 
calling the Washoe virus, same symptoms, one of my vets finally had one
horse rupture and was able to culture it, Strep Equi).  The embryo
ceased development a few days later and she resorbed shortly after that.
We're on our 5th try this year and I did some calling around and asked
a lot of questions of various reproductive experts, from her history all
say that she sounds like a normal mare, no history of infections, no
problem with clearance after breeding, she has had trouble with retained
CLs which prevented her from cycling much of the year a few years ago but
responds well to prostaglandins and has normal timing between cycles once
jump started, this year she didn't need any prostaglandins.  In addition 
to a few other things I brought up selenium as a question and I'm now 
bringing it up to this group especially the vets. 
	I live in the desert southwest, Arizona, while we are not in a 
chronically low area the vets around here tell me that our hay which is 
from Yuma on the border between AZ and CA often tests low in selenium. 
While that is the case the vets in this area don't routinely do selenium
tests and there haven't been any cases of white muscle disease in foals
that I'm aware of.  Supplements formulated (supposedly) for this area
do include some Selenium but not much, on the order of 1 mg per whatever
the standard measure is (I think it's per pound but I'm not sure).
When I discussed whether to have my mare tested or not the answer was 
that I could but it wasn't likely to be the answer since she is obviously
pretty healthy (she's the one who broke her leg badly last year, I'm
now riding her :-).  I asked how a mild selenium deficiency would show
up in lowered fertility and apparently that is currently unknown, all
we know is that it does lower fertility.  One vet, a practicing vet rather
than a researcher, said he thought that it would make them more prone to
infection (which is not my mare's problem).  The others said I'd have to
talk to a nutrition expert.  Sarah?  I am somewhat curious and have
questions:
	First, should this mare be tested?  If so I know there was a lab
mentioned about a month or two ago that was recommended, could someone 
tell me where it is and what samples they would need for a test (blood
samples, red top, purple top, have them send me a kit, what?)  And how
much it will cost?  Second, does anyone have a better idea of how 
selenium deficiency would interfere with a mare's fertility?  What range
should her blood levels of selenium be in, she is not currently active
except for regular turnout and occassional very light riding?   Before
pregnancy?  In the third trimester?  While lactating?  Do we have any
idea?  
	We ARE trying other things with her, she's been bred to
two different stallions, just in case she's allergic to the one we were
using earlier this season.  We've switched to AI from live cover, primarily
because the second stallion is in Colorado.  We used Regumate with her
the last two times and this one also because the first time she caught
was when we first put her on Regumate (we are planning to check her 
progesterone levels as soon as she's 8 to 10 days post-ovulation).  And
we flushed her twice this time to make sure there wasn't something going
on that wasn't showing up on ultrasound or culture.
	She was just bred 5 days ago.  Wish us luck!

					Tracy and everybody