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  Discussion on Oral regumate and progesterone shot
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Posted on Tuesday, Jun 25, 2002 - 8:23 pm:

My mare has taken the regumate for 10 days and then on the 11th day was given a progesterone shot. On the third day, she still was not responding to the tease/stallion. I was told that a second shot of progesterone could be given on the 4th/5th day to bring her in. ?? Would this harm my horse.
I understand that if given a estramate without a follicle developed could hurt her, I am concerned that giving this again would hurt her. Please advise as the 4th day is tomorrow.
Thanks

btw: I am not receiving the emails any more.

Posted on Wednesday, Jun 26, 2002 - 6:38 am:

Lola are you sure this is a progesterone shot and not a prostaglandin shot? The progesterone will not hurt her but it will not bring her in either.
DrO

Posted on Saturday, Jun 29, 2002 - 2:13 pm:

Lola,
not sure how this worked out for you...
but just now reading this, progesterone is to help maintain pregnancy, not bring a mare in to heat as Dr. O said. Progesterone is released by the CL of the egg that has been released and is now, hopefully, fertilized. I use progesterone in my older mares after I confirm them pregnant around 17-20 days as they need the extra boost! I hope your vet helped you straighten this all out. best of luck!

Posted on Monday, Jul 1, 2002 - 2:34 am:

Hello B,
Actually there is no evidence that a deficiency in progesterone early in pregnanacy is a common cause of early embryonic loss in otherwise healthy mares and minimum serum levels of 3 ng/ml are a arbitrary cut off point (Most recent reference: Reprod Domest Anim 2001 Aug;36(3-4):121-31
Luteal deficiency and embryo mortality in the mare. Allen WR.
Thoroughbred Breeders' Association, Equine Fertility Unit, Mertoun Paddocks, Newmarket, Suffolk, UK.)

For more on this see, Equine Diseases: Reproductive Diseases: Problems Keeping Mares Pregnant: Early Embryonic Loss & Abortion.
DrO

Posted on Tuesday, Jul 2, 2002 - 7:13 am:

Dr. O,
I read the article that you mentioned. So now I have some questions...obviously researchers can't confirm the benefits of progesterone shots, but what is controversial about it? Is there damage being done? I have a 22yo mare that has a foal by her side and is now in foal. I actually had her in foal in March but she aborted between 30-45 days, not on hormones. She is very easy to get in foal...but, now that she was confirmed pregnant at 20 days, I have her on 5ccs prog (don't know the exact concentration) once a week. I have another 20yo mare that aborted after 60 days last year and last foal was in 1999 and just had a fabulous 45 day check. At the 30 day check the embryo looked like it was smashed in the horn and last year before aborting, the embryo always looked like a peanut. Now at 45 days the embryo looks great.
So, is it all in my head that the progesterone is helping? or more importantly, is it damaging? If we say that supplying a mare with progesterone may decrease her own production of it, can we really honestly say that a 20+ mare having 8+ foals already is really the spring chick she used to be and producing enough hormones? I guess who's to know?
Thanks for your info, very helpful website, I enjoy it!
Bev

Posted on Wednesday, Jul 3, 2002 - 3:31 am:

Hello Bev,
I think the most controversial thing about giving a medication that is not needed is the millions of wasted dollars every year.

If you are asking are there any adverse effects to using oral progesterone, there appear to be very few. There is a slight increase in uterine infections with progesterone use but probably the most serious is that it prevents a mare who loses a embryo from returning to heat so early recognition of the lost pregnancy does not occur.

However if you are using progesterone in oil injections, they have to be given frequently, they are a painful medication, and frequently cause severe local irritation. Just last week I had a client's mare return to the farm that had been sent out to be bred with a hot painful volley ball size lump on the neck. Calling the farm they have given an injection of progesterone "to help with the trip home".

Decreased progesterone secretion is not a recognized feature of aged mares inability to conceive or carry. The limiting factor seems to be the condition of the uterus. Bev, I would be interested in the form of progesterone you are using and the dosage.
DrO

Posted on Wednesday, Jul 3, 2002 - 7:27 am:

Dr. O,
it is the injectible. I give one time a week, 5css, it is in oil, I will have to look at the bottle but I don't think it says anything else about concentration. My vet ordered it for me and it was sent directly to me. The vet I use is an excellent breeding vet, used by many major TB and QH farms in the area. I also get a lot of my advice from a major TB breeder that I do a lot of business with. But I have quickly come to realize, in this business, you will be told many different things from many different people and ultimately, I have to soak in everything that I am told and make the decision that is best for my mares/colts.
I haven't had problems with the injection site. I give it deep in the muscle. At this point, regardless if they absorb or abort, I will not rebreed so I will not need to detect heat again this season. I did wait on the two mares I use it on to confirm them in pregnant at 20 days by ultrasound. Since then, I have confirmed the younger in foal at 33 and 45 days. The older is not that far along yet.
As far as the limiting factor being condition of the uterus, I whole-heartedly agree with you there. As evidence of ultrasound, both mares have many endometrial cysts. I am sure that is what caused the 45 day or so absorption on the older mare this season. I never felt good about the ultrasound. Her tone felt absolutely great but we could never really see the embryo very clearly as it was resting in a bed of cysts. I didn't think it would be able to sustain there and of course it didn't.
I am not sure what the mentality here is on using the progesterone. I think it is combination that the older mares are not producing the hormones on their own combined with the fact that the uterus may not recognize the embryo because it is sitting on a bed of cysts. Therefore, give the progesterone. That is the best reason I have gotten out of my 'authorities.' As for me, I have no reason to ignore the suggestions as the one mare aborted already this season and the other slipped last season too late to rebreed. So far now they are both in foal, so I don't know.
At a certain point in the pregnancy, doesn't giving the progesterone become a moot point? For instance, after the formation of the endometrial cups? The progesterone is to help the uterus keep a favorable environment for the embryo that hasn't embedded or formed cups yet? As then the cups start producing their own hormones?
Thanks for all your info. Happy 4th!
Bev

Posted on Wednesday, Jul 3, 2002 - 11:25 am:

A good philosphy Beverly.
Progesterone in oil will not provide continuous progesterone for more than 24 hours unless very high doses are given and even then a couple of days is about all you can get:

J Reprod Fertil Suppl 1979;(27):211-6
Plasma progesterone concentrations derived from the administration of exogenous progesterone to ovariectomized mares.
Hawkins DL, Neely DP, Stabenfeldt GH.
Six ovariectomized mares were divided into 3 groups to determine the effects of exogenous progesterone in oil and repositol progesterone on plasma progesterone concentrations. Progesterone in oil was administered in 7 daily injections in Experiment I. Progesterone concentrations were not maintained greater than 1.0 ng/ml for 24 h with 50 mg/day. However, they remained greater than 1.0 ng/ml during the last 4 days of 100 mg/day and greater than 1.5 ng/ml throughout the injection sequence of 200 mg/day.

Progesterone is still important throughout pregnancy but that of CL origin is no longer required as you point out the placenta takes over the job.
DrO
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