what is is about the mare's uterus and the equine embroy that make it diffrecult to do sucessful ET. - from what I understand it is quite simple in the cow, but the mare is quite a different creature, what singling systems are involved? I think it has somthing to do with the embryo and it's requirement to transverse the uterus there by blockcking luteolysis - BUT does flushing the recipient mare irritate the uterus and cause additional release of PGF2-alpha or somthing like that - perhaps you could recomend some journal articles, as I'm looking for the scientific answer. thank you
Posted on Tuesday, March 25, 2003 - 01:23 pm:
Three of the biggest problems that contribute to this are:
The mare is often not as fertile as the cow to start with;
Superovulation cannot be achieved in the equine (or at least there is no commercial product available to cause it) so one is typically only going to be able to flush a single embryo rather than the multiple embryos that are often flushed in the cow;
Irritation of the equine cervix during transfer will cause a release of prostaglandin, which will be likely to threaten the transferred pregnancy.
There is a good article available in the archives of the EquineRepro@yahoogroups.com e-mail list available by going here, but you may need to be a member to access it.
Jos - At the Equine Ferility Unit in Newmarket one of the vets has designed a set of rat-tooth forceps. The success rate for transfers has rocketed because what they found was that normal forceps which pinch the cervix caused a crushing and bruising effect which released hormones causing the pregnancy to fail. These new forceps actually 'bite' into the cervix with one point on one side of the forceps and 2 points on the other side. They can pull the cervix very straight before trying to put the catheter through without having to 'grip'it too hard. The catheter then slides through, again with less disturbance. They have found this actually seems to cause less damage and therefore hormone production is minimised.
I am familiar with Twinks forceps! The results the the EFU is getting is better with their use, but it is worth noting that it has put the success rates in the same region as the non-surgical transfers performed at Colorado State University without their use (~75%), so it may be a combination of factors rather than the forceps themselves!
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