Using prostaglandin shot to "short cycle"

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Using prostaglandin shot to "short cycle"

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  • Shot to make mare come into heat
  • Horse breeding short cycle

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    03-13-2013, 06:32 PM
Using prostaglandin shot to "short cycle"

I've heard that (after having an ultrasound done to determine whether the mare is at an appropriate time in her cycle) a shot of prostaglandin can be used to "short cycle" her - ie: cause her to come into heat

Do people only use this immediately prior to breeding (like, have the shot administered in anticipation of breeding her via AI a couple days later), or is it also used to alter her natural cycles and basically "set" when they should occur (I know mares aren't totally regular)...

Say I had the shot administered and brought her into heat. Then let her go through that heat and back out... would she then likely cycle again approximately 21 days later? Or would she go back to her regular heat cycle.

The reason I ask is that I have a mare who goes through silent heats. I will be having a pre-breeding exam done this spring in preparation for breeding her in early to mid June. I am wondering if it would be possible to use prostaglandin to get her on somewhat of a predictable heat cycle.
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    03-13-2013, 06:51 PM
My mare was scanned and was coming on nicely. However she just wouldn't accept the stallion that first cycle, not sure why. Took her back to the vet about a week later, rescanned, and PG'd her. It's not nice stuff, she was sweating rivers on the way home in the trailer.

Took her back to the stallion 2-3 days later and all went great.

She also had somewhat silent heat. I had never noticed her come in heat ad she never played up to any other horses. Occasionally I would see messy back legs/tail, but I would never see the behavior.

I would guess that they would cycle normally after a PG cycle, but I'm not sure on that one.
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    03-13-2013, 06:53 PM
Forgot to say - my first choice would be natural cycles and just being on top of scanning to try and get the timing right. The only reason we PG'd instead of waiting is I wanted to have all her scans done before I went away so we were short on time. In an ideal world I would have kept scanning an waited for her next cycle.

Excuse the typos, on my phone!
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    03-13-2013, 07:10 PM
I would also like to scan her constantly in hopes of getting on top of it that way, but it may not be an option. I don't want to spare any cost because this will be her only foal, but I'm located very far north where any veterinary procedure is ridiculously expensive. I WILL be getting ultrasounds done, I'm just not sure how many are feasible.

That sounds pretty rough with the sweating and stuff, poor girl!

My mare is a maiden too which I've heard means that silent heats is not uncommon.

I do have access to a stallion and am considering paying his owners to let me use him to tease her. My problem is that until mid-April I work a job that takes me out of town for two weeks of every month, and then after that point I am moving and taking my mare with me... but we won't have access to a stallion after that point.
    03-13-2013, 09:28 PM
Big thing with PG is that it needs to be done after she has cycled normally, as in about a week, as otherwise you can mess up the development of the follicle due to the corpus luteum not being ready to make another oocyte.

We had a silent heat mare AI'd, and needed to use prostaglandin. However, we didn't get and shakes or sweating. If you know how to do an injection you can do it yourself, but you can't if you are pregnant. If you are pregnant and some PG is absorbed through your skin, your baby will abort. And in terms of ultrasounds, she had one to check out everything and when she would ovulate, we were given dates that we could give the PG and then had a couple (2-3) of ultrasounds to see when the best time to insert semen. The a 2 weeks wait, then another to confirm in foal.

The PG shot we gave was on the friday, and our mare came into cycle on Tuesday. So it is pretty quick. But this also means you can save on transports costs if it is early in the week, and you won't have to worry too much (hopefully) about missing her ovulation.

Best I know is that from then on that's her cycle, as her body still needs to undergo the ovulation, and reformation of the corpus luteum before she can ovulate again, and this will be the 21 days or so after the last ovulation.

Hope this helps!
    03-13-2013, 10:43 PM
Yes, my mare was a maiden too, I expect she will be easier to tease next time.

Be careful with relying on teasing. My mare, the first time we took her to the stallion according to the scan she was bang on. However she just wasn't interested in him - I left her there for about four days and he teased her twice a day but she just wasn't willing. She was squalling and pawing at him the whole time but no winking, squatting or squirting. Most likely because she was a maiden I guess. Not sure what made the difference the second time, but we tied her with the stallion through mesh and it took maybe 45 minutes to get her to squatting/winking stage.

She was scanned originally as part of a breeding check up, then again after she wasn't served to see if we could PG her. She was served around four times through the week then scanned around 14 and 45 days. I feel for you with the vet situation. I was lucky and had a lot of vets to choose from. However I chose the closest to make it least stressful on my girl and they were very $$$. I think it totaled around $600 for all the scans and the PG shot.
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    03-13-2013, 11:39 PM
Oh the joys of AI breeding,vet bills yes I have short cycled mares several times & it can be very helpful.The shot is used at the time before you are wanting to breed,if your mare is not in heat cycle, this will induce one to start. Best thing to do is have your mare examined by vet he can tell if she just ovulated recently or if she is just coming into a heat by feeling of uterus & follicles. If she just ovulated then you want to wait about 5-7 days before giving shot for it to be effective.If vet feels she is coming into a heat no need for the shot. Your vet is the best to advise in the the use of the shot,if you can't track your mare's heat cycles on your own. Agree It is much easier with mares that show there heats.
The mare will start a heat cycle within a few days of having received the shot,so you can plan on when to take her back to vet & have him start tracking her follicle growth.

If you have do access to a stallion now, go ahead & try teasing her see if she will show a heat cycle or 2 so you can try tracking were she is at & predicting following cycles it would make things easier
    03-14-2013, 06:52 PM
Thanks for the replies all!!!

And yes, $$$ will add up for sure ugh! But, this will likely be the only time I ever breed River, and it's very important to me that I breed her to a stud who I LOVE :)

Has anyone used "P+E"? (Progesterone & Estradiol Hormone Therapy)

I still have to see if teasing with my neighbour's stud is even an option - they may not agree. I was thinking that otherwise I might remove her from the main herd and keep her with just a mare for buddy. There's one gelding in particular who loves to woo the ladies, and I think if they weren't together all the time that he might be enough to get her to show some signs... hopefully. I THINK I've noticed her carrying her tail a teensy bit to the side occasionally... that might be the best "sign" I'll get out of her.

I read that you can get the "P+E" shots from BET Pharmacy with a veterinarian prescription, so maybe that could be a good option??? I just need to read into it a bit more and see if she has to be at a certain time in her cycle to use it or what. If so, that'll mean an ultrasound for sure. And if I use the prostaglandin it's sounding like an ultrasound needs to be done to make sure she's at an appropriate stage of her cycle.

Jacqua, so you had a total of 4 ultrasounds? One to determine time for prostaglandin, 1 or 2 to confirm that it was ideal to AI her then, and then the obvious for confirmation of pregnancy?

(plus I might be doing one during her breeding soundness exam)
    03-14-2013, 07:16 PM
Jacqua, so you had a total of 4 ultrasounds? One to determine time for prostaglandin, 1 or 2 to confirm that it was ideal to AI her then, and then the obvious for confirmation of pregnancy?
Yep, she had an ultrasound to confirm she wasn't ovulating, vet gave us possible dates to give the shot. I picked up the shot from the vets, and gave it to her while she was eating dinner at home (the poor girl lol) We dropped her off at the vets on the monday, they did an ultrasound - measured follicles and the such - and told us they would need the sperm on the wednesday. To save costs I met the stud owner halfway between our properties (i'm pretty lucky they were close) and dropped the chilled semen off at the vet. Third ultrasound to confirm the follicle was at a good size, then insertion of semen. Took her home that afternoon, then 14 days later her fourth ultrasound. Not sure how costs differ but (excluding semen) the whole vet bill came under $500 AU.

Another time we sent a mare to the stud, where the owners were able to do AI. She had had a breeding soudness exam earlier in the week, just missed ovulation! The stud owner gave her a PG shot, teased her, then on her third day in heat, the collected fresh semen from the stallion (He is a performance horse and didn't want to risk injury to either parties as she was maiden). Put her in the crush and inserted semen, so to an effect, it was a live cover... but not... She took first time, so the only ultrasounds she had was the soundness exam, and the one to confirm pregnancy. Also because the stud owner did it they were able to cut me a deal, about $300ish AU.

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