Horse Health: Breeding on Foaling Heat

In the past, most of our mares were pasture-bred to one of our in-house stallions. It was natural and easy. We had several premium stallions to choose from, we knew the mares were clean and there were no outside breedings to bring VD’s into the herd, and the breedings took place with little interference from us other than just making sure that a stallion was pastured with the right mares.

However, we are getting older and rarely keep stallions at the ranch any more. So deciding when to take a mare to an off-site stallion or when to import the semen from a distant stallion becomes a challenge. It involves a lot more coordination, money, time and more than one veterinary visit.

While we will not be going into all of the steps necessary to get a mare pregnant, I would like to touch on a few questions I had as a “newby” or questions I have been asked since becoming “more literate” about the whole process.

Most mares will cycle through a first estrus approximately 9-14 days postpartum (9-10 being the usual) and a 2nd estrus about 30 days after foaling. For our purposes, because we don’t own the stallions we breed to, it is certainly easiest to predict when the foaling estrus will occur so that we can be prepared to breed at this time rather than to guess when the next one will be. Therefore, in the case of most of our mares who experience normal pregnancies with healthy babies and good, healthy mothers, we breed on this heat cycle (days 9 and 11).

It seems strange to humans to have babies one after the other in such quick succession. However, our mares are kept in superb physical condition during pregnancy and generally deliver with no help and no negative repercussions. Should a mare look “poor” or out of condition before or after foaling, we generally wait 3-4 months to breed (depending on what time of year it is. You don’t want winter babies unless you have the facilities for it.)

Ultrasound can tell you if your mare is ready for breeding. If you ultrasound in days 7 and 9, you can make an informed decision about the timing. Mares who still have a large follicle in the uterine tube by day 9 or 10 can be bred normally. However, if they ovulate before day 9, the chances of a successful pregnancy are more remote, and it is best to do some prep work. Administer Prostaglandins 5 days after their ovulation to bring them back into season (called short cycling them). Then breed during the subsequent estrus. (Administering the hormones prior to 9 days is discouraged, as this early ovulation may not be as fertile.)

Research shows that a mare who has had postpartum complications such as dystocia, retained placenta, prolonged discharge etc. generally experiences a lower pregnancy rate and/or increased embryonic loss rate when bred on the foaling heat. Therefore, it goes without saying that such a mare should be held back from breeding until she is in condition to carry the foal easily.

The drawbacks and economics repercussions for waiting until a later heat to breed are obvious:

1. Unless you keep the stallion, there is scant way to reliably tease your mare to find out when she ovulates in a later cycle. Most mares have a pretty reliable foaling heat and then continue to ovulate about every 21 days, but that is not always the case. A veterinarian might have to tell you when she is next fertile by using an ultrasound on days 7 and 9 post foaling and keep checking on subsequent cycles.

2. A barren mare still eats. If your horses are pastured, and the foal is not a major producer of annual income, that may be of no consequence to you. However, if you pay for hay and supplements, she may be barren as much as a year (depending on what time of year you start the rotation) Dr. Patrick M. McCue at Colorado State University points out that, “owners that choose not to breed mares on the foal heat must accept the fact that eventually each mare will have to be left open for a season every 4 to 6 years when the potential foaling date becomes too late in the season.”

The mare’s uterus goes through some dramatic changes post postpartum. It contracts, eliminates fluids and debris, and generally gets ready to implant another embryo. This is all a very natural process. Oxytocin or prostaglandins are sometimes used to “push” the uterus into condition to enhance foal heat conception rates.

Of course, I can’t speak for the millions of foaling mares in the world, but our mares have never needed any of this procedure. If your livelihood does not depend on your mare having a foal each year (and even if it does), we think it is best to breed as naturally as possible. And, considering the genetic implications of mares who are notoriously difficult to get pregnant, it might be a good idea to drop them from the gene pool. Read: Genetics Made Simple

How old is too old for a “breeding” mare?

Of course that depends on the mare, her history, her condition, her living conditions, etc. Many mares conceive and have very successful pregnancies into their mid 20’s. If a mare has never had a foal (maiden mare), and she is getting into her late teens, it might not be a good idea. However, our mares really seem to love having babies. They carry them to term. They foal with no help. They are fantastic mothers who would never wean one if they didn’t have to. If she is in great condition and has routinely had foals, mid-20’s is not unusual.

Fertility begins to decrease at about 15 years, so be aware that the rate of successful pregnancies begins to decline as well. A mare who has routinely had foals seems to stay fertile more reliably than a mare who is left barren for several years. Additionally, older mares are more susceptible to other conditions that might negatively affect pregnancy such as uterine scar tissues, endometrial cyst formations, inflammations or uterine infections and unreliable ovulation. Some older mares lose condition in the vulva (wind sucking) that invites bacterial infections. While all mares experience some degree of inflammation after breeding, if the mare is older and experiences a condition whereby she cannot expel the excess seminal plasma, and debris, such unhealthy tissue can make the uterus incompatible with embryo survival.

You may find that “the mare knows” best. When it is too late, she may not conceive or carry to term anyway.

What to expect from a live, physical breeding.

Know that stallions should be (but are not always) gentlemen. And mares are not always willing participants. Many people hobble the rear legs of a mare to prevent her injuring a prize stallion if she doesn’t want to cooperate. By the same token, a stallion may feel the urge to bite the neck of your mare as well as flail his front legs around giving her a few knocks on her back as he mounts. While willing, she may still get a boo-boo or two.

We wrap the mare’s tail in vet wrap to keep from getting it tangled or introduced into the vulva. Strands of horse hair are very strong and could damage either the mare or the stallion if hair gets caught and cuts. Wrapping also helps the stallion find his target more easily.

If you are breeding a mare with a foal by her side, be sure that the mare can see her foal during the process. He should be safely out of harm’s way but within her range of vision.

Use a knowledgeable stallion handler. The stallion can get quite excited. He is big and could be dangerous. Additionally, many times, a handler has to help to place the penis into the vulva – especially for an inexperienced stallion or mare.

The case FOR Artificial Insemination

While we have always loved the natural setting of pasture breeding for our own horses, we find that breeding without a stallion at our ranch brings its own problems. There are many reasons why A.I. is good:

1. You can choose from the best horses regardless of distance. While we like to think that our own breeding stock is stellar, it is very nice to be able to choose the absolute BEST genetic match for your mare from among nearly limitless choices. Not every stallion is worth breeding. Read: About Stallions

2. Your mare does not get “beat up”. The act of breeding is not necessarily a gentlemanly sport. Stallions can be rough, especially if hampered by human efforts.

3. Your mare will not contract any diseases or infections from properly prepared semen.

The case AGAINST A.I.

1. Semen is expensive to collect, ship and administer. It frequently takes many visits to the vet to get ready for a good semen introduction. You want to be sure (via ultrasound and/or palpation) when she is in season, and you want to introduce the semen deep into the canal where it will move forward to fertilize. The added expense of helping to do what nature would do in the pasture has to be added to the overhead. Our estimate at this time is a minimum of $1000-$1500 added expense. A foal needs to be worth a lot to pay for his inception, his Mom’s keep, his own keep and still make a profit (if that is the goal).

2. You can waste a lot of time and money if the people involved in the process (veterinarians, collection personnel, shipping and handling personnel etc) are not very knowledgeable. You will need to know exactly when to breed, have the necessary hormones available, have the spermatozoa on hand at precisely the right moment etc. It’s no small feat.

3. The best AI takes place using fresh semen where the mare and stallion are in the same location but not actually physically coupled. Fresh semen is usually the least expensive and has the best viability. The timing of frozen semen is much more critical. It is the most expensive and least viable – though sometimes the only option. Frozen semen requires repeated ultrasounds (sometimes every 6 hours) to pinpoint the exact time of ovulation and inseminate immediately after she ovulates (when the follicle is gone indicating that the egg has been released). Ideally, that will reduce the number of inseminations to just one.

4. It’s a whole lot easier to do the whole thing the natural way.

After the breeding

Breeding horses at Kristull Ranch is a labor of love rather than a financial necessity. We breed very few horses at this time, and take care of nearly everything naturally and easily. That includes checking to see if the mare “took” the breeding and is indeed pregnant.

Because most mars do not “look pregnant” until they are very advanced into the term, palpating is included in the breeding routine. We are not experts and are not always successful determining if she is in foal during the palpation. For that reason, we also watch her behavior in the months following for “teasing” the stallion or generally showing cycling behavior.

The last time Aukara was palpated, we filmed the procedure for those not familiar with it.

The conclusion today is that she is NOT pregnant. However, she has not been seen teasing the stallion near her paddock. We have not seen her show any signs of cycling, so we are hoping we are wrong. She has fooled us before. I will keep you updated as we observe changes in her behavior or if she actually delivers a live foal. In this case, we actually hope that we are “dummies” once more.

An amusing aside: My 13 year old son wanted to be a veterinarian until he witnessed this procedure being done by a veterinarian friend. He wasn’t properly prepared for it (nether was I). Unfortunately, it was so repugnant to him that he became a computer programmer instead. He LOVES his work, but I believe he would have made a great vet too.

Please note that this advice is neither veterinary nor prescriptive in nature but offered only as an introduction to this topic.

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