Hi there! It’s Winnie the Clinic Mouse, and guess what? I’m a quintuplet, which means I have four siblings who were born at the same time as me! It’s quite a busy and exciting life, having so many siblings. But that’s not all—one of our veterinarians, Dr. Carter, is a twin! It’s fascinating to see how different species experience multiple births!

In the world of mammals, many of us can have multiple babies at once. For mice like me, having a bunch of siblings born together is pretty normal. But for horses, it’s a whole different story. While some mammals handle multiple births with ease, twin pregnancies in horses can be very dangerous.

Causes of Twin Pregnancies

Twin pregnancies in horses occur when two ova are fertilized simultaneously. This happens when a mare double ovulates or releases two eggs. While this may sound like an advantage for breeding, it often leads to complications.

Risks Associated with Twin Pregnancies

The main risks of twin pregnancies in horses include:

• Abortion: The majority of twin pregnancies end in early embryonic loss. The limited space and nutrient availability within the uterus make it challenging for both embryos to survive.
• Dystocia (difficult birth): If the pregnancy continues to term, the mare is at a higher risk of dystocia, which can endanger both the mare and the foal.
• Abnormal Foals: Even if twins are carried to term, they are often born weak and underdeveloped due to the shared resources in the womb.
• Mare Health Issues: The mare can suffer from complications such as retained placenta, which can lead to severe infections.

Diagnosing Twin Pregnancies

• Early detection of twin pregnancies is crucial. This is why the 14 day pregnancy check after breeding is so important. At this time, we can diagnose and manage twin pregnancies.
• Ultrasound Scanning: A veterinarian can perform an ultrasound around 14 to 16 days post-ovulation to detect multiple embryos. If twins are identified, steps can be taken early to manage the situation.

Management of Twin Pregnancies

Once twins are detected, it is highly recommended that the mare does not continue to carry both embryos and that one embryo is removed, or the pregnancy is terminated due to the high risk to the mare and foals in twin pregnancies.

• Selective Reduction: This is the most common and effective method. One embryo is manually reduced via ultrasound guidance, allowing the remaining embryo a better chance to develop normally.

Twin pregnancies in horses present significant challenges and risks, but with early detection and appropriate management, these risks can be mitigated. Understanding and managing twin pregnancies effectively can lead to successful breeding outcomes, despite the inherent difficulties. If you plan on breeding your mare, make sure you follow the recommended pre- and post-breeding appointment plan from your veterinarian. It’s a lot of appointments, but for very good reason!

Until next week,

~Whinny

P.S. Have you listened to all of the breeding episodes on my Doc’s podcast? They have a number of different episodes about various aspects of breeding, and you won’t want to miss any of them! You can find them over on the Podcast Page of my website, or subscribe to Straight from the Horse Doctor’s Mouth on Apple Podcasts, Spotify, or wherever you get your podcasts!

Spring is in the air, the birds and the bees are out, and foals are hitting the ground. Everyone seems to be thinking about making more of them! Don’t we have enough horses in the world? I think we need more mice. But seriously, breeding your horse is a significant decision that requires careful consideration. In the United States, we’re facing an overpopulation of horses, and adding more to the population should be a thoughtful choice. While the idea of passing down desirable traits, like behavior, movement, personality, or talent, can be appealing, it’s crucial to know that these traits aren’t always inherited by offspring. Each horse is unique, and what makes a great performer or companion doesn’t always transfer to the next generation.

Moreover, breeding a mare especially demands foresight and planning for the foal’s future. It’s essential to have a well-thought-out plan for the foal once it arrives, including a budget set aside for potential health issues in its early days to weeks of life. Consider that if a foal can’t be sold due to genetic issues or a lack of desired talents, the responsibility for its care falls on the mare owner for the rest of its life. This responsibility extends far beyond the cute foal stage into adulthood, which involves time, finances, and dedication. Making the decision to breed should involve serious consideration of the long-term commitment to the foal’s well-being, ensuring a stable and secure future for both the mare and her offspring. And if you’re looking to make a profit from breeding horses, just cut your losses now! I can’t even tell you how many financial horror stories I’ve overheard at the clinic from owners losing money on breeding.

Whinny’s Wisdom: MOST people who breed horses do not turn a profit from it. Don’t count on ANY foal to be a financial windfall!

Understanding Mare Reproductive Health

Reproductive services for mares should involve comprehensive examinations, utilizing diagnostic tools like ultrasound and hormonal assays, and scheduled follow up exams. This helps identify any potential issues that could hinder fertility, such as uterine infections, hormonal imbalances, or structural abnormalities.

Various health problems, from infections to systemic conditions, can affect a mare’s fertility. Addressing these concerns early is crucial. Treatment options may include antibiotics, hormonal therapies, or management adjustments to enhance overall reproductive success. It’s also very important to consider if it is worth pursuing breeding in a mare with any of these reproductive conditions. Basically, do you want to breed A horse, or do you want to breed THIS horse?

Pre-Breeding

It pays to be prepared! Before any birds or bees are brought together, there are some important steps. First of all, is your mare fit and healthy enough to be bred? Let’s go over what information we need to figure that out:

Vaccination Status: All horses should be vaccinated regularly by the veterinarian you have a great relationship with, but it’s even more important for a broodmare whose immune system will be challenged by growing a brand-new creature for 11 months. Our docs require mares to be up-to-date on vaccinations for diseases like Eastern and Western Encephalitis, Tetanus, West Nile, Equine Influenza, Equine Herpes, and Rabies. Go check out some of Tony’s old blogs to learn about these vaccines if you’re curious!

Dental and Hoof Health: Regular farrier visits and dental care are vital for maintaining a mare’s health during pregnancy. Would you want to carry an extra 100 lbs in your abdomen if you already had bad feet or a toothache?

Reproductive History: Knowing if your mare has previously foaled or been bred helps us understand potential complications or issues that might arise during the breeding process. Any previous reproductive diagnoses, such as uterine infections or cysts, are critical to know about and potentially manage prior to insemination. A mare that has had a difficult pregnancy previously won’t necessarily repeat that, but she may. Similarly, a mare that’s had very easy pregnancies in her past could always have a difficult time this go around. It’s important to be emotionally and financially prepared for above-and-beyond care if your mare has a difficult pregnancy. This can involve frequent exams, medications, or even hospitalizations. If your horse has not ever been pregnant before, this can also sometimes present challenges, especially if she is older than 8-10 years of age.

The prebreeding reproductive evaluation is a pivotal step in ensuring a successful breeding outcome. Through the use of diagnostic tools like ultrasound, uterine culture, and cytology, our doctors comprehensively assess the mare’s reproductive health. Ultrasound examinations offer valuable insights into the reproductive tract, detecting structural abnormalities, cysts, or inflammatory changes that might hinder fertility. Uterine cultures identify bacterial infections within the uterus, enabling targeted antibiotic treatments to resolve underlying issues. Concurrently, uterine cytology evaluates the cellular composition of the uterine lining, pinpointing inflammation or irregularities that could affect the mare’s ability to conceive or carry a pregnancy to term. This comprehensive evaluation empowers veterinarians to proactively address potential issues, optimizing the mare’s reproductive health and significantly increasing the chances of a successful breeding experience.

Turn the Lights On

For early breeding (before March/April), implementing a Light Protocol helps regulate the mare’s estrous cycle. This involves simulating longer daylight hours to prompt hormonal changes, preparing the mare’s reproductive system for an earlier breeding season. This process typically begins around 60-90 days before the desired start of the breeding season, usually in late fall or early winter.

How to Implement a Light Protocol:

1. 1. Light Duration and Intensity: Mares are sensitive to light changes. Mimicking longer daylight hours tricks their bodies into believing spring is approaching, stimulating hormonal changes. Provide artificial lighting in the mare’s stall, ensuring 16 hours of continuous light daily. Natural and artificial light combined should meet this duration.

2. Light Timing: Start the Light Protocol in late fall or early winter. Calculate backward from the desired breeding date, allowing 60-90 days of light stimulation before the intended breeding season begins.

3. Light Management: Ensure consistent lighting without interruption. Use 100-200-watt LED, incandescent or fluorescent bulbs placed approximately eight feet above the mare. The lighting should be evenly distributed throughout the barn, including the stall where the mare resides.

4. Light Control: Use automatic timers to maintain a regular schedule. Artificial light should start early in the morning, simulating dawn, and continue until late in the evening, mimicking dusk. Avoid sudden changes in light intensity or duration.

Implementing the Light Protocol at the right time is critical. For early breeding, starting the protocol around late November to early December allows for the required 60-90 days of light exposure before the breeding season, typically beginning in February or March. Regular monitoring during the Light Protocol ensures proper response. Veterinary guidance and monitoring hormone levels may be necessary to confirm the mare’s readiness for breeding after the completion of the light exposure period.

Timing

As they say, timing is everything. Once our team has determined your favorite mare is all ready for a bun in the oven, the work has only just begun. Horses have a 21-day estrous cycle, but the period of fertility (estrus) varies from 2-8 days across each cycle, with the length of diestrus (uterine inactivity) adjusting to keep the cycle at about 21 days. Because of this variability, it is crucial your mare have ultrasound assisted reproductive exams OFTEN. When I say often, I mean sometimes multiple times per day. The margin for error in timing depends on how you are planning to have your mare bred.

In general, we have the most flexibility if the mare will be live covered and the least flexibility if she will be artificially inseminated using frozen semen. This usually means you are either boarding your mare at our clinic (yay, more friends for me!) or trailering her in every 1-3 days until she is bred. After the deed is done, we have to confirm she has done her part and released an egg. This is also done with ultrasound. Then, there’s more to schedule!

Fourteen days after confirmed ovulation will be the first pregnancy check. That 14-day mark is super important, because we have to look for twins. Horses are super particular with their insides (see all of our colic blogs!) and their insides can absolutely not handle two babies at once. So, if we find twins, we have to “pinch” one of the embryos in order to save the other embryo and the mother. But we can only do this very early in her pregnancy.

After that fourteen-day check when she is confirmed pregnant, one of the nice technicians at the clinic will email you a Pregnant Mare Schedule which details the next 11 months of her and your life. She’ll be visiting us at least every few months for ultrasound exams and vaccines until her baby is born. And if you feel anything is going wrong in between those frequent visits, she will visit us then too!

Conclusion: Breed Responsibly

While the thrill of breeding your mare is enticing, responsible breeding involves thorough consideration and preparation. Each mare is unique, and individualized care to whole horse health is vital for successful reproduction. At Springhill Equine, our docs prioritize individualized care and thorough assessment to maximize the chances of a successful breeding outcome. Our aim is not just conception but ensuring the health and well-being of both mare and foal.

I think I gave a pretty thorough lecture today, but if you would like any further information or to schedule your mare’s reproductive evaluation, you can speak to our lovely office staff by calling 352-472-1620.

Until next week,

~Whinny

P.S. If you really want to get intense with breeding knowledge, my docs have several seminars on the topic over on our YouTube Channel. They are way more in-depth than my blog, and completely free! You can find all of our Seminars by Clicking Here.

Hey everybody, Whinny here! It’s almost December, so it’s time to start thinking about breeding mares. The best plan is to avoid breeding altogether and buy a horse that’s grown up, trained, and ready to go. But for those of you who like to do things the hard, painful, expensive way (with no guaranteed outcome!), let’s get into the weeds.

The cycle of reproduction in mares is a complex process, but having an understanding of this process allows us to manipulate a mare’s reproductive cycle to increase our chances for successful breeding. In this post, we will explore the key stages of mare reproduction.

Stage 1: Estrous Cycle

The estrous cycle, also known as the “heat” cycle, is a crucial stage in mare reproduction. Unlike mice and humans, horses are seasonal breeders, and their estrous cycle is dependent on the length of daylight. Typically, the cycle occurs during the spring and summer months when the days are longer.

The estrous cycle lasts approximately 21 days, during which mares experience various behavioral and physical changes. These changes are regulated by hormonal fluctuations. As a mare enters her heat cycle, she may become more receptive to a stallion’s advances, displaying signs such as frequent urination, vocalizations, and a more relaxed stance of the tail.

Paws! Stage 1.5: Anestrous and Transitional Mares

In contrast to the estrous cycle, mares also go through periods of reproductive inactivity called anestrous. Anestrous is the phase when mares experience a temporary cessation of their estrous cycles and show no signs of heat. This usually occurs during the colder months of the year, particularly in late fall and winter when daylight hours decrease. The reduced exposure to daylight triggers hormonal changes that suppress the estrous cycle, allowing mares to conserve energy and prepare for the challenges of winter.

Additionally, mares undergo a transitional phase before entering full anestrous or during the transition from anestrous to the onset of the breeding season. This period is known as the transitional phase, or transitional estrous. During this time, mares may exhibit irregular heat cycles and display mixed behavioral and physical characteristics of both estrous and anestrous. This can make it difficult to determine the mare’s actual reproductive status and is one of the greatest challenges when breeding mares.

Stage 2: Ovulation

During the estrous cycle, the mare releases an egg from her ovaries through a process called ovulation. Ovulation usually occurs around the end of the estrous phase, approximately 24 to 48 hours before the cycle ends. If a successful mating occurs during this window, there is a higher chance of conception.

Stage 3: Fertilization

Fertilization is the process of the mare’s egg being successfully fertilized by the stallion’s sperm. The sperm can survive within the mare’s reproductive tract for several days, increasing the likelihood of fertilization if mating happens close to ovulation.

Stage 4: Pregnancy

Pregnancy is confirmed with an ultrasound at 14 days after ovulation. Horse gestation lasts approximately 11 months, although it can vary slightly depending on individual factors. During this time, the developing embryo implants itself in the mare’s uterus, where it receives nourishment and protection throughout the gestation period.

Stage 5: Parturition (Foaling)

Parturition, or foaling, in a mare unfolds in distinct stages, each essential for a successful and healthy delivery. The first stage is marked by behavioral changes, such as restlessness, pawing, and repeated lying down and getting up. This is accompanied by the relaxation of the muscles in the mare’s hindquarters.

The second stage involves the actual birthing process, where the foal is expelled from the uterus. The mare may lie down and get up repeatedly, and the amniotic sac containing the foal usually ruptures. The foal’s front feet and nose appear first, followed by its shoulders and body. The mare actively participates in this process by contracting her abdominal muscles.

The third stage involves the expulsion of the placenta, which is critical for the mare’s health. This process usually occurs within a few hours after foaling. Monitoring and assistance during these stages are crucial to ensure the well-being of both the mare and the newborn foal.

The Rest of the Story

These five stages are what happens when everything goes right. As you may know, if you’ve been a horse person for more than a few weeks, it’s unlikely that everything is going to go right with breeding. There are a variety of problems that can happen at every stage of pregnancy, and many of them stop the process. And it’s not uncommon for a mare to be bred repeatedly and still not get pregnant (just like people. Mice don’t have that problem).

There are a lot of factors that make a mare a good or bad candidate for breeding. One of the biggest ones is age. I know you humans can get confused about how old your horse is, and how that translates to human years. Let me give you a rule of thumb chart to go by:

Horse  Human (equivalent age)

  3            15
  6            25
  10          35
  15          45
  20          55
  25          65
  30          75
  35          85

Horses are just like people: they are really fertile when they’re young (think 4-7), and once they get past a certain age (think 10), everything becomes high risk and high difficulty (and highly not recommended).

Our team of expert veterinarians can do a lot of things to help you set your mare up for a successful breeding. There are no guarantees in reproduction, but if you do all the things, your odds of success are greatly improved. It’s no different than anything else in life, really. The first step is talking to my docs and making a plan in December so that all the pieces can be put in the right place at the right time. You can do that with a simple call or text to the Clinic at 352-472-1620. And make sure you bring me a little bit of cheese when you come in for your pre-breeding exam!

Until next week,

~Whinny

P.S. If you’re serious about breeding your mare, you’ll want to listen to all the comprehensive breeding episodes of Straight from the Horse Doctor’s Mouth, which is the podcast my docs produce. It’s loaded with great information that you won’t want to miss out on. You can subscribe on Apple Podcasts, Spotify, or anywhere you get your podcasts, or just check them out over on the Podcast Page of my website.

This past week has been a busy one at the clinic for me. All my paddocks have been full, and all my stalls occupied. I’m exhausted, but it’s been very rewarding to see all the foals frolicking in the paddocks. We are well into breeding season and have been performing pregnancy check after pregnancy check. These appointments are stressful yet rewarding. As the doctors are scanning the uterus looking for one little black dot, the suspense could be cut with a knife. As a cat, I can feel it as the mare’s owner, the doctors, and the technicians wait, then I hear it: the cheers that mean that a little black dot has been found! It’s heartbreaking when the dot isn’t found. And maybe even worse than not finding the black dot is seeing two black dots.

Twins

Double the dots does not mean double the fun. Two black dots on a pregnancy check means that there are two embryos developing, and two embryos means twins. Unlike many other animals, twins in horses is not a good thing. Fortunately, the development of two embryos is not super common, but when it happens, it’s important to know early on. That’s why my doctors always highly recommend a pregnancy check 14 days after known ovulation. There’s a very narrow window to deal with twins. Between days 14 and 20 of pregnancy is the only time that twins can be managed without major risks. We’ll talk about management of twins while in-utero and what can be done to ensure the birth of a single healthy foal, but first let’s discuss what happens when twins are not managed in-utero.

At your mare’s 14-day pregnancy check, your veterinarian will thoroughly examine your horse’s uterus and ovaries via transrectal ultrasound to find a pregnancy and ensure that only one embryo is found. If two embryos are found, the suggestion will be to “crush” or “pinch” one of the embryos. A mare’s uterus is not capable of carrying two healthy foals to term. The likelihood of a mare having twins that survive to foaling is extremely rare. If a mare does foal out twins, it’s unlikely that one or both of the twins will survive for more than a day or two.

If twins are not detected between 14 and 20 days of pregnancy, aborting the pregnancy becomes one of the options early on. To do this, a medication is administered to the mare which gets rid of the Corpus Luteum. The Corpus Luteum produces progesterone which helps maintain a pregnancy. Once the Corpus Luteum is gone, the embryos won’t be able to survive. After 150 days of pregnancy, the Corpus Luteum no longer holds the pregnancy and endometrial cups take over to provide progesterone and maintain pregnancy. If twins are not detected until after 150 days of pregnancy, aborting one or both of the fetuses becomes extremely difficult and dangerous. Transabdominal procedures are performed to abort a fetus, which puts the other fetus as risk for abortion as well.

Incomplete Ossification of Cuboidal Bones

If a mare carries twins to term and both survive, it’s likely that they won’t be developed completely. Despite being born full-term, when twins are born, they come out as premature foals. One problem that premature foals have is lack of bone development. More specifically, the small bones of the carpus (knee) and hock do not develop before birth in premature foals and in this case, twins. During the development process in-utero, the cuboidal bones in the carpus and hock start off as cartilage and turn into bone in the later stages of development.

When twins are born, their bones usually aren’t developed, and they have a significant amount of cartilage present in these joints. If foals were like human babies and laid around all day, having knees and hocks made of cartilage wouldn’t be an issue because they wouldn’t be holding up 200 pounds on cartilage alone. When the weight of a foal is placed on cartilage, it crushes the cartilage so that when bones develop, they’re misshapen and will develop arthritis before the foal is even a few months old. As you can imagine, this leads to a very painful, difficult life for the foal from day one.

Lung Development

To go along with the prematurity of twins is the lack of lung development at birth. The last thing to develop before a foal is born is their lungs. That’s why we never induce foaling unless we absolutely have to. When twins are born and have premature traits, one of the largest concerns is their lung develop (or lack thereof). When their lungs are not developed appropriately, they can’t get enough oxygen to survive. Without supplemental oxygen they will not thrive, not grow, and will be prone to illness.

Other Developmental Issues

Because twins have to share a placenta that can’t fully support them completely, they are born small and are more prone to developing illnesses. Being small in stature makes nursing difficult and increases the risk of developing aspiration pneumonia. They may require an indwelling feeding tube and being fed every few hours via the tube. The mare may not develop enough colostrum to supply both foals with enough antibodies to supply them with a strong immune system. When a twin does not get enough colostrum, they require treatment with intravenous plasma to ensure they have appropriate antibodies to fight off diseases and illnesses. Twins will require intensive treatment, they often require hospitalization, and they are not easy. Moreover, they are not cheap.

The moral of the story is, have your brood mares monitored early, monitored frequently, and appropriately cared for should twins be found on 14-day pregnancy ultrasound. While it might seem like you are getting more bang for your buck if twins are found, listen to your veterinarians and their recommendations if twins are found. It is, in fact, a life or death scenario for the foals and the mare.

Until next week,

~Tony

P.S. If you’ve ever read any of my post scripts, then you know about the Podcast and the YouTube Channel, and you’ve subscribed to both. You’ve also probably already scrolled down and subscribed to my blog. So, really, you’re plugged into all the things, and absorbing horse knowledge in every way that I have to share it. Pat yourself on the head, and give yourself a treat, becaue you are a good human.