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Posted on 09-22-2014

Why Isn’t My Mare Pregnant??

(Part 1 of a 3 Part Series)

Breeding season: the thrill of victory and the agony of defeat.  If you are feeling more defeated than victorious at the end of this breeding season, you are probably wondering what went wrong and how can next season be successful.

To explore the answers to this question, I find it helpful to break down the potential problems into three categories: mare, stallion, and management.  (Just plain bad luck might be considered another category, but that doesn’t need any explanation!)

We will tackle these issues in reverse order, starting with management, since these problems are often the easiest the change. (Stay tuned in the next two weeks for mare- and stallion-related problems.

What I mean by “management-related problems” is basically how we humans have manipulated the breeding process; these are issues that are not intrinsically related to either the mare or stallion. Artificial insemination (AI) requires a great deal of coordination between veterinarian, mare owner, stallion owner (which may also include breeding farm and stallion’s veterinarian) as well as the delivery/courier services that get the semen from stallion to mare, so it’s little wonder that things can go wrong! (Don’t stop reading here just because you aren’t using AI to get your mare bred—many of the suggestions to follow will help improve your natural service breeding program!)

My first suggestion is to always confirm that the mare has ovulated after insemination.  This is REALLY important and often overlooked. (Yes, it seems like common sense and some of you experienced breeders who are reading this are saying to yourselves, “Duh! We thought she had some super cutting-edge advice for us!” My response: the basics are always worth repeating.)  It’s understandable why you might be tempted to skip the follow-up exam that your vet has recommended to confirm ovulation after breeding.  After all, the vet has been out multiple times to check this mare; you have coordinated her cycle to the stallion’s collection days, ordered and received the semen, and inseminated the mare. Do you really want to pay for another farm call and mare exam? Yes! Yes, you do! Here’s why: semen doesn’t live forever and if it has been more than 2-3 days between insemination and ovulation (fresh or cooled semen; frozen semen has a much shorter lifespan) then the chances are not great that the semen is viable. Nonviable (dead) semen equals little chance of pregnancy.  If your mare hasn’t ovulated on time, order some fresh semen and breed again!

Similarly, always confirm that the mare still has a follicle prior to insemination.  (Again, we are not discussing frozen semen protocols: that’s another blog topic altogether!) I think some clients suspect that I just want to make an extra buck when I tell them that we are going to recheck the mare’s follicle prior to insemination (“but you just checked her last night Doc!”), but my actual reason is to confirm that this breeding has the best chance of success. Unlike sperm cells, egg cells (oocytes) only live for 6-8 hours after ovulation. So if 24 hours have elapsed between the time the mare was last checked and the time that semen arrived for insemination, a mare that has already ovulated prior to breeding is much less likely to get pregnant. The solution to this problem isn’t as clear cut because it is NOT possible to determine precisely when a mare has ovulated within a 24 hour timespan by palpation or even by ultrasonography. (We will come back to this controversial topic in another blog!) The mares that have ovulated in the last eight hours may conceive, but the others have a much lower chance of conception.  Some mare owners elect to breed the mare anyways and take their chances; some prefer to scrap the cycle and start all over.

Tip three is for those of you who have mares that show heat (estrus behavior) readily to other horses on the property. Don’t rely on teasing/behavior alone to time your inseminations or to confirm ovulation. Yes, for hundreds of years people have used behavior as an indication of when to breed a mare; these people also never spent $500 for each semen collection, plus $250 extra for airline delivery on a Sunday.  Many mares continue to show heat after ovulation, some don’t start teasing until they have ovulated, and some never show at all even though their cycle was perfectly normal. It is not a precise system, even in a live-cover program. If you have been relying on teasing alone with no success, talk to your vet about how combining exams with teasing can improve your results.

Many vets routinely use an ultrasound in all reproductive exams (not just pregnancy diagnosis) but if your vet has been relying on palpation alone, ask for an ultrasound exam to confirm follicles and suspected ovulations.  I can’t tell you the number of times that I have examined a mare and said to myself, “yep, she’s ovulated”, only to apply the ultrasound probe and be proven wrong! It’s not always possible to feel the difference between a soft follicle, an ovulation or a problem such as a hemorrhagic anovulatory follicle. Trust me, ultrasound is the way to go—even if it costs more, it’s well worth it.

My next suggestion will make your life easier and earn the gratitude of whoever is shipping semen for your mare.  Understand the stallion’s collection schedule: which days, when to call, who to call. Share this information with your vet!  Make sure you include stallion’s name, mare’s registered name (do you know how many Sweeties and Bellas there are?!) and her registration number.  Also, if the breeding contract is in another person’s name (partner, trainer, etc.) include that information.  Of course, ordering the semen is part 1: the sequel is planning for the delivery.  Know what delivery services the stallion owner uses and how that will work with your schedule. For example, if you know that the semen will be shipped overnight, arrive around 10:30am and will require a signature upon delivery, make sure that someone can sign for it! I learned this one the hard way—some delivery services don’t accept the signatures of children under 16 (mine was a responsible 13 year old at the time) and it is virtually impossible to get your package on a Saturday afternoon once they have taken it back to the holding facility for the weekend. That is the difference between live semen and dead, between a follicle and an ovulation, and between a pregnancy and an unhappy mare owner…and that is a management issue, pure and simple.

My last tip relates to the above topic and concerns scheduling: learn enough about the mare’s estrous cycle to help coordinate pregnancy exams and potential rebreeding.  No, I don’t mean that you need to take a short course, buy a textbook, or (shudder!) ask “Dr. Google”! Like I said before, AI requires a lot of coordination between vet, mare owner, and stallion owner. Everyone is busy; weekends, holidays, vacations, and horse shows happen and can potentially delay re-breeding your mare if she doesn’t conceive on the first cycle. It can really help if the mare owner understands WHY the pregnancy check needs to be done on a specific date. Here’s an example: your vet wants to check your mare for pregnancy on a Friday, but you are leaving for a horse show that weekend. You ask if the exam can be performed the following Friday. What’s the big deal?  If your mare is pregnant, it isn’t a big deal; however, if your mare isn’t in foal, she will come back into heat and likely ovulate in that intervening week, and you will miss that chance to breed her a second time.  Understanding the basics of the mare’s cycle and discussing the timing of exams with your vet can make the most efficient use of the breeding season.

This list of management-related problems is definitely not complete, but I hope it gets you started in analyzing what you may be able to improve on next breeding season. Next week I will tackle Part 2: stallion-related issues. Have comments or questions? Please get in touch by email, phone, Facebook.

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