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  Discussion on I'm just making sure I'm reading the articles correctly
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Posted on Thursday, Apr 4, 2002 - 9:57 pm:

Hi Dr. O

As I posted earlier my mare was checked in foal at 18 days post breeding on last Thursday (March 28). On that day the vet drew blood for a Progesterone level. He called me back today and said her level was really low at 2.0. He suggested a redrawing blood for a recheck, and then a progesterone shot "just to be sure" while we are waiting for results.

After reading your articles I got the idea that there is no evidence supporting supplementary progesterone to keep my mare pregnant. Did I read that correctly?

I really don't want to put my mare on Regumate nor do I want to give her any progesterone shots if I don't need to.

She's 18 years old. Her uterine culture was clean (I didn't do a biopsy). In the past, every time she has become pregnant she has stayed pregnant. I have never had her progesterone level checked before. It has been 3 1/2 years since she's had a foal.

I'm getting quite a bit of pressure from my vet and from the stallion owner to give my mare the progesterone and I guess I just want to make sure that I'm not doing any harm by not giving it to her.

Thanks for your help.

Heidi

Posted on Friday, Apr 5, 2002 - 5:42 am:

The issue is more complicated than the statements you make above Heidi. As someone who has studied the literature and breeds horses I do not use progesterone in my practice for early embryonic loss because I do believe at this time there is evidence to support the practice. A recent review of the literature leads Dr. Allen to make this comment last year which echoes my sentiments:

...In the face of this interlocking and failsafe system for progestagen production throughout pregnancy, and despite a paucity of evidence that a deficiency of progesterone production is a cause of pregnancy loss in the mare, it is surprising, and worrying, that annually many thousands of pregnant mares throughout the world are given exogenous progestagen therapy during part or all of their gestation as a form of preventative insurance against the possibility of pregnancy failure. Basic investigative research is required urgently to validate or debunk the practice.

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.

The problem is it is nearly impossible to prove something has "no effect" but it is certainly fair to say this medication is greatly overused.
DrO

Posted on Friday, Apr 5, 2002 - 2:18 pm:

Thanks for your words of wisdom Dr. O

Since I posted I also talked with the reproductive specialist at the vet clinic I usually use (for pregnancy related things). All he does is reproduction. However he doesn't travel as far as my barn, so I have to head up there (1 1/2 hrs) to utilize his services.

When I talked to him today, he agreed with the opinion that a low progesterone level at this point doesn't mean that the pregnancy is in trouble, especially since she has no history of early embryonic loss. According to him, many mares with lower progesterone levels, maintain their pregnancies just fine. He recommended that I wait and see. I will definitely take my mare up there for her 40-45 day preg. check.

FYI, he also thinks that many mares are on Regumate to make their owner's happy, but doesn't think it does a whole lot.

Thanks again.
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