Getting your mare in foal – the choices, costs, and considerations

So you have decided that you want a foal out of your favorite mare…..

She is your best show horse, never lame or sick, and can handle any type of rider on her back.  You know she won’t be around forever, and she has the conformation, genes, and temperament that you want in all of your horses.  Once you start thinking of her future foal(s), you start to get really excited.  And getting her in foal should be pretty easy, right?  Just throw the mare and stallion in a pasture together and they will get the job done.  Then 11 months later you will have a beautiful healthy foal running around your pasture with its mother while you sit on your porch and enjoy a lovely cup of coffee.

Dreaming of your mare and foal playing in your pasture…. Source:  kimballstock.com
Dreaming of your mare and foal playing in your pasture….
Source: kimballstock.com

Sorry to interrupt the daydream, but here comes the voice of reason :(.

Things are usually not quite that simple.  Yes, the above scenario sometimes does happen.  However, depending on multiple factors (breed of horse, age of mare, etc.), getting a mare in foal can be a challenge.  I’d like to discuss some of the considerations, choices, and costs that the mare owner should be aware of before deciding to breed their horse.

Considerations

Age of the mare:  If your mare has never foaled before, she is termed a “maiden mare”.  Older (over 13 years) maiden mares are notoriously difficult to get in foal for the first time.  If your mare has had foals in the past but is now older (over 20 years) she may also have some troubles getting pregnant.

Breed of horse:  Depending on the type of stallion you would like to breed her with, you may not be able to have your mare bred by the stud in a pasture (“pasture bred”).  Sometimes the nearest quality stallion is located hundreds of miles away, in which case you would have to trailer your mare out to that farm and leave her there until they told you she was bred.  Then you get to trailer her back and have your vet confirm the pregnancy.  Don’t get me wrong – this procedure is quite common in the Thoroughbred world – but most other breeds ship semen to you for artificial insemination.  Artificial insemination is unfortunately not as simple as just injecting the semen into the mare and walking away – more on that later.

Choices

The “stud”:  One of the most exciting parts about getting a mare bred is getting to pick out her stallion.  There are websites and magazines galore with beautiful pictures of stallions and lists of their accomplishments.  And when you are dreaming of that foal it is fun to picture what each stallion could contribute to compliment your mare’s traits.  Some practical things to think about once you have narrowed down your search include:

1)  The contract.  CAREFULLY read and re-read the breeding contract and make sure you understand it.  If not, ask your veterinarian or trainer or other horse professional to go over it with you.  Some contracts have “live foal guarantees”, others do not.  It is important to understand exactly what you are paying for and why.

It is important to understand everything outlined in a breeding contract when selecting a stallion for your mare. Source: Equinelegalsolutions.com
It is important to understand everything outlined in a breeding contract when selecting a stallion for your mare.
Source: Equinelegalsolutions.com

2) The breeding stats.  It is a good idea to know how many live foals this stallion has produced per year, how many mares he is bred to each year (his “booking”), and the average number of times a mare is bred to him before she gets pregnant.  Additionally, if you are having his semen shipped for artificial insemination, you want to know how well the semen ships, and average number of shipments before a mare gets in foal.  If a stallion owner says “This stallion got 10 mares in foal last year” – that is a very vague statement.  You don’t know how many mares he attempted to breed, how many live foals were born, and what type of breeding took place.  He could have bred over 100 mares, gotten 10 in foal, had 2 live foals, and bred 20 mares in pasture and 80 mares via artificial insemination.  Ask the stallion owner the hard questions.  If they refuse to answer them, then something fishy is going on and it is best to choose another stud.

3)  The reputation of the stallion, breeding farm, and owner.  This runs along the same line as the stats.  If things seem kinda shady, they probably really are.  A stallion owner who is trying to sell semen should want to work with potential buyers and answer their questions honestly and promptly.  If you request to visit their farm, they should be more than happy to take you on a tour!  You are the customer and the way they make money.  Obviously, don’t be obnoxious and call at weird hours :).  A good piece of advice is to speak with other mare owners and get recommendations on studs and breeding farms.

Type of breeding.  Almost every breed association accepts foals born from artificial insemination (The Jockey Club / Thoroughbreds are the only one I know of that insists on having natural mating take place).  If you decide to have your mare bred via AI (artificial insemination), then you may need to choose between frozen semen or cooled, fresh semen.  The costs and breeding statistics differ between the two, so careful consideration needs to be made when choosing.  Which brings us to the costs….

Costs

Costs can add up very quickly when breeding a mare.  For each type of breeding, lets talk about the costs that can surprise mare owners.

Natural/pasture breeding

1)  Trailering to and from the stud – gas, wear and tear on trailer, travel fees (food, hotel, etc).

2)  Mare care at the breeding farm – food, vet care (for injuries, sickness, pregnancy checks).  Mares usually live at the breeding farm until they get pregnant, so if it takes 2 or 3 cycles for her to get pregnant you could be looking at those costs for 2-3 months.

4) Follow up vet care – have your vet make sure the mare is still pregnant.

Artificial Insemination – Frozen or Cooled Semen

1)  Initial vet exams to determine timing of breeding –  Artificial insemination needs to take place very close to ovulation (preferably 24 hours before ovulation) so the sperm will reach the egg soon after it is released.  This requires that a vet does serial ultrasonic evaluations to determine the when the mare is going to ovulate.  Each ultrasound costs money, as does the vet visit.  Often a more money-saving method is to leave your mare at the vet clinic and have them do the ultrasounds and actual insemination when it is time.

2)  Cost of shipping semen – Semen must be shipped overnight to the mare, which can be expensive.  Additionally, each semen collection from the stallion may have its own separate fee.  The breeding contract should spell all of this out.

Horse herds in the wild, such as Chincoteague ponies, have foaling rates from 50 to 75%.  Horse owners should not expect 100% of mares to get pregnant the first time trying. Source: chincoteagueislandvacations.com
Horse herds in the wild, such as Chincoteague ponies, have foaling rates from 50 to 75%. Horse owners should not expect 100% of mares to get pregnant the first time trying.
Source: chincoteagueislandvacations.com

For any type of breeding there is always the chance that it takes more than one attempt to get pregnant.  In nature or in wild herds, the average foaling rate is around  50-75%.  That is with multiple natural breedings over a season in a low-stress environment.  Now put the horse in a higher stress environment with semen that has been shipped across the country and the chance that the mare gets pregnant in one try decreases to around 50% or less.  Horse owners often are shocked if their mare does not end up pregnant after one attempt at breeding and are dismayed when they only budgeted for one round of insemination.  A good source for hard data regarding breeding statistics is on the Select Breeders website.

Additional expenses may be incurred depending on the individual mare.  Some mares have immune reactions to the semen, which causes very unfavorable environment for a pregnancy to occur.  Your vet may attempt to fix this reaction with antibiotics, anti-inflammatories, and uterine lavaging.  Other times the mare may need a small surgical procedure to correct vaginal conformation abnormalities.  Hormonal injections may be needed to ensure the mare ovulates within a specific timeframe.  Your mare also may need to be supplemented with progesterone-like hormones to maintain her pregnancy.  Each case is different, so it is best to plan for a flexible budget when it comes to breeding. Breeding horses can become complicated and expensive, which can lead to frustrated mare owners.  Careful considerations regarding the stallion, type of breeding used, and budget planning can go a long way to easing the stress of getting a mare pregnant.  I hope to add more posts regarding the details of artificial insemination and horses, but first I wanted to give a broad overview of the information owners need to be aware of before breeding their mare.

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Understanding seasonal cycles in mares

First I want to apologize for not posting last week, but I was on vacation and out of the country.

Second, since today is the first day of Spring, I figured it would be a good time to help mare owners understand their horse’s seasonal reproductive cycles.  I also aim to describe what behavior changes to look for in your mare, as well as help you understand what methods are available to help modify behavioral issues in mares.

Mares = Seasonal Polyestrous

Animals go through what we call “estrous cycles”.  This means they only are sexually receptive at certain times.  In contrast, human females go through “menstrual cycles”, but are sexually receptive throughout the cycle.  The estrous cycle can be fairly complicated and differs greatly among animals.  For simplicity, I will just discuss the estrous cycle of the horse.  For comparison with other species, visit the Wikipedia page on the estrous cycle.

The yearly cycle of the mare.  During the winter months the ovaries are "dormant" and the mare does not have estrous cycles. Source: myhorseuniversity.com
The yearly cycle of the mare. During the winter months the ovaries are “dormant” and the mare does not have estrous cycles.
Source: myhorseuniversity.com

Mares have what I like to think of as 2 types of estrous cycles – a yearly cycle, and within that yearly cycle, a monthly estrous cycle.

Yearly Estrous Cycle

During the winter months, when there are few hours of daylight, the mare is in the portion of her yearly cycle termed “anestrus”.  During anestrus the ovaries are inactive and the mare does not go through her estrous or “heat” cycle.  As daylight hours increase in the spring and summer the ovaries become active again.  The mare will now have ~21 day estrous cycles throughout the long spring/summer/early fall.  Thus, the term “seasonal” (spring/summer/early fall) “polyestrous” (many cycles).

Monthly Estrous Cycle

Once the mare’s ovaries are active in the spring, she will develop a follicle(s) on her ovary(ies) and release an egg(s) about every 21 days.  These 21-day cycles are each called an estrous cycle (I know, its very confusing!) or a “heat” cycle.  The mare is only sexually receptive to the stallion during the phase of the estrous cycle known as “estrus”.  I am not sure why the two terms “estrus” and “estrous” have to be so similar and confusing, but thats how it is folks.

The 21-day estrous cycle is repeated while daylight hours are long enough to cause the ovaries to be active.  Behavioral estrus is also termed "heat" and is the period of time when mares show outward behavior changes indicating they are ready to be bred. Source:  extension.org
The 21-day estrous cycle is repeated while daylight hours are long enough to cause the ovaries to be active. Behavioral estrus is also termed “heat” and is the period of time when mares show outward behavior changes indicating they are ready to be bred.
Source: extension.org

Behavior Changes During Estrus

For about a week (1-7 days) most mares will show outward signs of heat.  Some are very demonstrative, others barely show any changes.  The behaviors seen during estrus are there to alert to the stallion that the mare is receptive to breeding and will not kick his head in when he comes looking for love.  These estrus behaviors include:

– increased urination frequency

– holding the tail to the side or constantly lifting the tail

– “winking” of the vulva, especially after urination

– extra sensitivity to touch and stimuli

– unpredictability

– squatting

– decreased eating and drinking

– excitable, restless, “running the fences”

– increased vocalization and squealing

The video embedded below shows typical estrus behaviors in mares.

Modifying and Preventing Estrus Behavior in Mares

Many of the above behaviors are not exactly helpful for performance and show mares.  Some mares have such drastic behavior changes that they can become a danger to their riders and handlers.  In these cases, many clients turn to their vet for help.

Some of the methods used to suppress unwanted estrus behavior in mares include intrauterine marbles, synthetic progesterones, oxytocin administration, and surgical removal of the ovaries.
Some of the methods used to suppress unwanted estrus behavior in mares include intrauterine marbles, synthetic progesterones, oxytocin administration, and surgical removal of the ovaries.

The logical way to prevent estrus behavior is to prevent estrus all together.  How is that accomplished?  Several methods are available to horse owners, some more drastic and permanent and others temporary.  There are actually many options for estrus suppression, lots of them still experimental, and I am not going to go through them all.  To simplify things, I will state that there are two basic proven ways to stop estrus in the mare.

Method #1:  Trick the body into thinking it’s pregnant (aka the birth control method)

Basic principle: Progesterone is the hormone produced by the body when there is a pregnancy. When progesterone levels are adequate, the body stops going through reproductive cycles until progesterone levels drop (not pregnant). In the mare, once an egg is ovulated a structure forms on the ovary called the corpus luteum. The corpus luteum produces progesterone, which prepares the mare’s body for pregnancy. If the mare becomes pregnant the corpus luteum stays intact and continues to make progesterone, which stops the reproductive cycle from continuing.

Screen Shot 2015-03-20 at 1.33.49 PM

Method #2:  Remove the source of the hormones (ovaries) surgically

Basic principle:  The ovaries are the main source of the hormones (estrogens) thought to be the cause of estrus behavior in mares.  Just like removing testicles causes stallion-like behavior to cease, the removal of ovaries should theoretically cause estrus behavior to stop.

Screen Shot 2015-03-20 at 1.39.57 PM

Like many issues in medicine and reproduction, there is not a one-size-fits-all solution to the problem with estrus behavior in mares.  One point that I must emphasize, however, is this:

DO NOT JUMP TO BLAMING BAD BEHAVIOR ON HEAT CYCLES!!!!!!!

A mare's bad behavior can not always be blamed on her estrus cycle!   Source: thehorse.com
A mare’s bad behavior can not always be blamed on her estrus cycle!
Source: thehorse.com

In order to determine if estrus suppression will even help with issues regarding your mare’s behavior, there must be a clear and scientific correlation between unwanted behavior and her estrus cycle.  My first piece of advice is to get a calendar dedicated to tracking your mare’s behavior and her heat cycles.  Write down every time you see her show a sign of heat as well as when she is behaving abnormally.  Then, when she is at her worst, have your vet ultrasound her ovaries to confirm that she is in heat or estrus.  If you show your vet your calendar of behavior and cycles, along with the reproductive examination, your vet will most likely be able to determine if there is a strong correlation between her behavior and her cycle.  At that point your vet will recommend a course they deem appropriate to help curb unwanted estrus-related behavior.

If there is no correlation, though, then I suggest working with a trainer to help correct these behavior problems.

Hope you are all having a wonderful spring day so far!