View Full Version : Chorulon and ovulation

01-01-05, 08:45 AM
Does anyone have any experience with this ?

Long story....first experience of breeding and unfortunately it hasn't been straightforward like we hoped.

Mare has returned twice and the vet/stud managers aren't sure why. The mare in question is a 14 yo maiden. She is in good health, appears to be cycling normally and "shows" very strongly when in season. On having her scanned, it appeared that everything is normal and that she produces follicles.

The vet seems to think she is not ovulating for some reason, so she was given an injection of chorulon and was then served on 2 consecutive days.

What does the chorulon actually do? I think I read somewhere that it induces ovulation, but I don't know much more than that! Any comments/info appreciated!

If she returns again I will get her swabbed to rule out infection. Can anyone think of any other reasons why she is not going in foal? The stallion is very fertile, so guessing it is a problem from her end...just not sure what!

01-01-05, 12:02 PM
Yes it does mke them ovaluate within a given time (can't remember how long). Usually given when mare has a good sized follicle >5mm (?). You should speak to the stud and the Vet for fine details. What breed is your horse. Chorulon is used a lot in TB world. Pagan

01-01-05, 04:54 PM
Acacia, there could be any number of reasons 'why isn't she going in?', and infection could be one of them. More experienced breeders will be able to give you a more definate idea, but I haven't really had a 'difficult' breeder before. Something as simple as the PH levels in the uterus can affect the ability of the mare to maintain the fertilised egg. Stress levels when travelling can also affect the PH levels and make them either too alkaline, or too acidic (not sure which!)

I know other things can affect the fertility of the mare, even if she is getting folicles. The chorulon stimulates ovulation within a certain period, usually 12-24 hours later from our experience with AI so far. Mare is scanned each day until she shows a 35ish mm folicle, then she is choruloned, and scanned every three hours over night and usually inseminated the next morning, if everything goes according to plan. Chilled and live cover they like to do just before ovulation, and with frozen, they like to inseminate just at ovulation.

My TB mare whose foal is now 10 weeks old, last year when she went to stud, stood in the middle of her paddock for the first five days and weaved, because she was very unsettled in her new environment. When they moved her to a different paddock with a gelding for company, she settled straight away and the gelding teased her on immediately. She was covered by the stallion a few days later, and subsequently went straight into foal.

Maybe it's something as simple as the mare not being settled in the surroundings? I don't know, can't give you any more answers I'm afraid!

Good luck with this cycle, anyway.

PS, been meaning to email you but computer has been difficult, how do you like your rug?

02-01-05, 12:44 AM
Chorulon induces ovulation at 36 +/- 4 hours. But the mare can ovulate earlier if she was going to do so anyway. It will not put off ovulation, it can only bring it on earlier.

Has your vet checked for hemoragic (sp) folicles. they can stop her from getting pregnant, and at her age and still being a maiden can cause problems. The recommend that the first foal is had before the mare reaches 10 yo. Some older maidens have no problems others have fertility problems.

Good luck I hope that they work it out for you.

02-01-05, 09:04 AM
Hi MandyE

She has been at stud since mid/late October and apparently is settled in now. I think the reason she returned the first time was because they had her seperated to begin with, and she fretted badly. As soon as she was put out with others though, she relaxed. The stud owners were suprised when she returned the second time. I am quite prepared to give it a bit more time - I realise that there could be any number of reasons why she is returning. As for the rug - it's going well, Bones loves it as it keeps the dratted flies off!! ;-)

Dutch - what procedure is done to check for haemorhagic follicles? I hadn't heard of that as a possibility! (there's too many things that can go wrong, it seems!) Yes, in an ideal world she would have gone to stud by the time she was 10, but she was my only riding mount up until recently, so this wasn't an option. I know that at 14 it could be a bit trickier, but that is why I am trying now and not leaving it any later.

Fingers crossed she will get in foal. If not, I will buy a youngster with the breeding I want later on. I am trying to not have too pessimistic an outlook, but at the same time trying to be realistic!!

14-01-05, 01:15 PM
I have used it twice, both times in anovulatory mares. First time it did nothing obvious, 14 yr old maiden did nothing, didn't obvioulsy ovulate, never got served, never got pregnant. Second time 16 yr old maiden ovulated two days afterwards got served and pregnant.
For product info check out http://www.intervet.co.uk/Products_Public/Chorulon/090_Product_Datasheet.asp.

re other reasons, how long is your piece of string? (and how deep are your pockets?) But I'd be asking vet to do a real good ultrasound and check her out. And a swab and maybe even a uterine biopsy if you are keen too. And then maybe giving up and trying again next Spring.

This year has been very odd for getting mares in foal. My stallion (who paddock serves) can usually tell where mares are and time it right, and he has got 17 mares in foal, in fact everyone he has served. But I have had troubles getting some mares to cycle normally. Early in the summer was better for conception. Couple have been anovulatory, one had regumate and pg treatment and looked in season but still would not stand for him, one retained fluids and brewed up a metritus, all of these older mares (14-16). Other breeders nearby have reported similar with their mares, having trouble cycling normally. And it is getting worse now late in the season too. Only yesterday I heard officially this is the driest summer since 1954 in our area. Maybe that has to do with it???

15-01-05, 04:15 AM
thanks for that info!! yes I had my share of probs with the tb mare...

pooling and reaction badly to frozen... fluid everywhere!!!

I have had to cut my losses and sell her on ... breaks my heart as she was a lovely type and had 4 foals previously, but don't have the $$$$ to keep spending..

bought cheapo tb mare off track, went straight in to stallion.. :P

cheaper in long run !!!

15-01-05, 07:25 AM
Yes Lorraine - I have been told it is a bad season for getting mares to cycle - we have had hot weather, then cold, then hot, then cold...

I will get her investigated if she doesn't go in foal this cycle (should find out soonish). That will then determine whether I bother perserving with her or not. She will go back into work otherwise!!!