I know that as part of Jos' myths article, it says that mares are extremely unlikely to have a reaction to extenders, however, we've had two experiences this year that have made me think:
8 y/o, 1 foal at 5 y/o. hCG'd on 38mm follicle PM, AI'd following AM. Huge amounts of fluid (4cm). Washed out and infused with antibiotics. 14 days, not pregnant. Next cycle, hCG'd on 35mm follicle AM, AI'd following AM. Oxytocin given every 12 hours. Still loads of fluid, no pregnancy.
I spoke with the vet, and suggested more aggressive oxytocin therapy, but he was convinced that it was the extender causing an "extreme" reaction. Phoned the stud, and this extender was an egg yolk-based extender (Spervital, Holland).
This cycle, semen was extended with Equipro. Mare hCG'd with 36mm follicle 12pm, AI'd following AM. Oxytocin every 12 hours for 48 hours (same as 2nd cycle), but NO fluid (well, 0.5cm 12 hours after AI). Mare still pregnant at 28 days.
12 y/o, 5 foals, "easy breeder". 42mm follicle PM, inseminated with semen from Germany following AM (egg yolk extender). Given oxytocin every 12 hours for 48 hours post AI. Vet has a great U/S, and spotted "severe" inflammation the following day (having had a saline washout). Not in foal at 14 days.
Next cycle, similar story, but eliminated saline washout, as we thought that might be the source of the inflammation. Still very inflamed following AI, and not in foal again.
Third cycle, AI'd with raw semen, but otherwise the same protocol. No inflammation or fluid this time. Preg scan next week.
Any thoughts? Has anyone else eliminated egg yolk extenders because of problems like this? Or were we just unlucky/was the problem unrelated to the extender?
My 14 yo mare (had 4 foals by natural covering) could not get in foal last year with frozen or chilled semen despite best efforts. Assumed she was having a "reaction" to the extender (egg yolk) so sent her down this year for AI with fresh semen (the stud does not do live cover). However mare had loads of fluid, injected / flushed out etc but no luck. NOT pregnant but came back laminitic (see my posting prostaglandin v. laminitis). I will never do AI again.
Jamie: Pretty much anything will irritate the uterus, but seminal plasma is noted as having a mitigating effect for irritation. Almost certainly what you are seeing is mares that have a delayed uterine clearance issue, and treatment with oxytocin at 12h -hourly intervals is inadequate. Every 4-6 hours is more suitable, as oxytocin has a half-life of 6.8 minutes, so about 35 minutes after giving it circulating levels are dissipated (although there will likely still be tissue level activity until about 2 hours post-treatment). Re the seminal plasma - remember that one of the treatments suggested for mares that have major post-breeding inflammatory response is to infuse seminal plasma.
Sally: I'm sorry to be so blunt, but your position on not using AI is ill-educated and short-sighted. The mare's uterus gets worn with repeated pregnancies, and it's ability to clear fluids becomes less over time - that's the condition known as "delayed uterine clearance". It has been clearly demonstrated repeatedly, that the use of a single timely and well-performed AI will give far better pregnancy rates than live cover, particularly in older (and older is a term relative not only to age, but wear-and-tear) mares. To base a decision not to ever use AI again on one mare - and one that is a likely candidate for DUC at that - is erroneous, and probably going to restrict your success rate for breeding, particularly with older mares.
Thanks for replying Jos, I appreciate it especially bearing in mind how busy you are.
Based on the observations above, do you think that it is possible that egg yolk prevents the seminal plasma having its quietening effect on the uterus, through interacting with molecules in the seminal plasma? I guess this might be why egg yolk is an effective preservation additive, but would explain the difference between AI with milk-extended semen vs yolk-extended semen?
Or is that stating the obvious?
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