Posted on Wednesday, November 27, 2002 - 06:03 pm:
My mare has had four pregnancies using frozen semen. The last of those was an embryo transfer. When we prepared to do another embryo transfer last year, again with frozen semen, she had an allergic reaction to the extender. There was so much fluid accumulation in her uterus that she couldn't get pregnant. We tried twice with the same reaction. Subsequently, she took with cooled semen and we got a successful transfer. Has there been much research into using different types of extender or what can be done to help a mare with this type of reaction get in foal?
Posted on Friday, November 29, 2002 - 06:34 am:
Research has shown that a "reaction" such as you describe (which is actually an over-production of a natural response seen to some extent with any breeding method - live cover, cooled semen or frozen semen) is not as a result of the extender, but rather the sperm that have been destroyed (the technical term is "lyced") during the freezing/thawing process. Unless a different extender is used which results in fewer damaged/destroyed sperm, changing extender is unlikely to make any difference.
There are however other techniques that can be used to assist in a reduction and clearance of this post-breeding inflammatory response:
Post breeding treatment with oxytocin at 4 hours after the insemination, and then the treatment being repeated every 6 hours until as much as 3 and a half days after ovulation (there is an article in the articles section of the web site that details this treatment); inta-uterine lavage with a saline solution to clear the retained fluid (this should be coupled with the oxytocin treatment if you perform the lavage); insemination with a small (+/- 5 ml) volume of seminal plasma at the same time as semen insemination (seminal plasma has a "quitening" effect on the uterus); reduction of the insemination dose volume and sperm number, with the insemination taking place at the utero-tubule junction (this is more complex, and will require an equine reproduction expert to perform).
It is also worth considering that there may be a tendency in this mare to have a problem with "delayed uterine clearance", so keep a close eye on her with any form of breeing in the future, and be prepared to use the oxytocin protocol if this appears to be a problem.
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