My mare had a CL earlier in the season and I gave her the 2 reduced lutalyse doses. She came into heat on the third day post 2nd dose. Since she has previously had some extended heats, I waited until the 4th day of heat to breed her by live cover, but she was already out! Follicle monitoring by a repro vet would have been great there, but it is not available to me where I live.
I know from past experience that she will have clearing problems if frequently covered, so I am trying to minimize the number of covers. (This mare was once inseminated w/fresh cooled semen 3x on a 9 day heat without any fluid problems (used oxytocin) and had a successful pregnancy, so I am hopeful she won't have a serious DUC issue.
But she is older now, 14. Now she has a CL again and I am using 2/dose Lutalyse again. This will be my last chance this year. I am thinking of breeding on the 3rd day of heat and every other day until she is out, but I welcome any suggestions for live cover schedule and oxcytocin use- or anything else. We have had very strange weather this year and mare cycles have been weird and unpredictable. The plants are confused, too- my rhododendrons are blooming in August instead of May!
Nothing sounds particularly unusual in what you report. It is not uncommon for mares to have a shorter estrus (earlier ovulation) in the height of the breeding season, and 3 days to onset of estrus following Prostaglandin F2α treatment is absolutely normal.
Commencing breeding on the third day of standing heat and breeding every other day until she is no longer receptive to the stallion is a standard protocol and works well in most cases.
There is an oxytocin protocol on our site that we recommend and have used with good success ourselves (follow that link).
Can't comment on the psychology of rhododendrons...
Thank you! I am familiar with the oxytocyn protocol. I did wonder, though, about recently reading that oxytocyn was naturally produced during live covers but not when the mare was inseminated. Even if this is so, it still seems a good thing to use oxytocyn prophylactically on a live cover. If the semen lives for at least 3 days after a live cover, it seems breeding on day 2 might be insurance against the mare flying through the cycle again, and still perhaps not require another cover even if she is in 4 days, or give her better clearing time even if she is covered again on day 5.In the absence of certainty of follicular size, would it still make more sense to wait for day 3? Does a rapid onset of heat after Pg2 likely indicate a shorter number of heat days, too? I know ideally the breeding time would be 12 hours before or 6 hours after ovulation for shipped semen, but does the chance of pregnancy also increase with a live cover near ovulation, as long as it is within 3 days of ovulation?
While oxytocin is produced during teasing, if a mare has delayed uterine clearance issues (DUC), unless she is very borderline, teasing is still not going to produce enough oxytocin to reliably control the DUC, and exogenous oxytocin is still warranted.
In a perfect world, when dealing with a DUC mare, one would breed by AI 2 (or even 3 days if with semen with known longevity) prior to ovulation - something called a "minimum contamination breeding". That does however require repeated ovarian checks to determine follicular development and confirm ovulation. My personal feeling if follicular checks are not available would be to breed on days 3 and 5 rather than 2, 4 and probably 6.
A rapid onset of estrus following treatment with Prostaglandin F2α will often result in a rapid ovulation - as soon as 24 hours after dosing in some cases. See the prostaglandin article for more details (follow the link).
With shipped semen with a DUC mare, it is better to go a little earlier than a little later in my book - as long as the stallion has known longevity of sperm survival. Up to 24 hours prior to ovulation is fine and in some cases more can be achieved (although that starts to get risky!). The tendency is to try and aim closer to ovulation with shipped semen primarily because there is no guarantee about what the sperm will look like after transport, so there may be a reduced number available to get the job done. Additionally, it is important to remember that - even if things go right - shipped semen is usually 24 hours old before it gets in the mare, so in a sense - from the sperm's point of view - you are actually "breeding" the mare 36 hours prior to ovulation even if she ovulated 12 hours after she is actually inseminated! So with a mare that ovulated 24 hours after being AI'd with shipped semen, remember that the semen is probably 48+ hours old at that point!
There would be a marginal increase in pregnancy rates with breeding LC within the 12 hours prior to or 6 hour post-ovulation window, but it is probably not statistically different from LC 24 hours prior to ovulation.
This is very much like a mare I am breeding here. She was bred once, after showing heat for only one or two days. Ultrasound was done to determine pregnancy. She was not in foal, had a 31 follicle, but the cervix was extremely tight, and the uterus was not as it should be for a mare in heat. We decided with a possibility that the embryo might have been hiding, not to breed her but ultrasound again a week later.
Next ultrasound, she had just ovulated, carrying a CL, so we brought her back in with Lutalyse. She came in heat within 2 days. We bred her by A-I on what appeared to be day 2. The cervix was very tight (1 finger). Next day we did another ultrasound, and she had a 38 follicle. She had fluid in one horn, so was given oxtyocin, although it was speculated that the fluid could have been from the previous days breeding. Jos, is that common?
She was bred again the day after, and the cervix was so tight that only the pipette went in. Afterwards I followed your oxytocin protocol.
This is a young, healthy mare who has never had a foal. Supposedly she was a maiden, but we are not convinced.
The tight cervix is a puzzle. Also, she does show better heat when she has received Lutalyse, which makes me wonder if there is a small hormone issue. Pregnant or not, she will go home for the winter (N. Ohio) with fingers crossed that she has settled. I have recommended a progestrone test, just in case she has funky hormones.
I am not familiar with the reduced Lutalyse treatment. Can you point me to that information? I'd thought about giving this mare Lutalyse more than one day, but didn't.
Without ensuring a relaxed cervix, one is almost certainly going to end up with retained fluid and failed clearance post-breeding. Performing a uterine lavage may be beneficial in that case, as you are mechanically draining the uterus via the catheter, but relaxing the cervix would still be beneficial. There has been discussion elsewhere on this board about how to do that, and the use of digital manipulation and topically applied PGE cream are common treatments. A new treatment that I have not yet had the chance to evaluate, and which has not to the best of my knowledge been the subject of peer-review is to topically apply Buscopan to the cervix.
Estrogen is the hormone that causes relaxation of the cervix, and that originates from the follicle. If you are dealing with a non-dominant follicle then there may be inadequate estrogen present. This could be as a result of attempting to breed on a mid-cycle follicle - was there uterine edema present prior to breeding per ultrasound?
If you search the board, you will find all the necessary references for the reduced Prostaglandin F2α treatment - it's been discussed here several times.
On the last ultrasound, my veterinarian did not mention whether or not there was uterine edema present, and I forgot to ask. The first time we ultrasounded her, there was not - at a 31 follicle.
I am not real confident, after this discussion, that this mare is going to settle, all things considered. Maybe with what we've learned, we will have a heads up for next year.
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