Artificial Insemination

Mares can be artificially inseminated with fresh, cooled or frozen semen. Breeding fertile mares with cooled or frozen semen of fertile stallions can be simple and efficient and result in pregnancy rates similar to fresh semen. Easy access to mares for examination is essential to achieve good pregnancy rates with artificial insemination. Before mares are initiated in the breeding program at Bella Vista Equine, a complete reproductive exam is performed to determine if treatment is necessary. Uterine cysts are mapped and recorded to avoid confusion during the pregnancy exam. Mares that fail to get in foal in previous breeding seasons or have an abortion or dystocia, and older maiden mares may require additional diagnostic exams such as uterine biopsy. A very small piece of tissue is taken from the uterus and sent to the laboratory for analysis. Based on the biopsy results we can determine if there is any inflammation or scar tissue in the uterus and initiate treatment accordingly.

Mares will be monitored daily at Bella Vista Equine Services for estrus behavior. Uterine culture swab is obtained to determine if the mare is carrying an infection. Follicular development and uterine changes are monitored by rectal palpation and ultrasound and the findings are recorded for daily follow up. Mares are bred within 48 hours from ovulation for fresh semen, within 24 hours for cooled semen and within 6 hours from ovulation for frozen semen. Mares are checked for accumulation of fluid post ovulation and treated with uterine lavage and/or oxytocin when needed. Mares found to be infected may also benefit from additional treatment post breeding. Problem breeders may require additional treatment at the time of breeding, and the treatment may vary with severity of the sub-fertility. We also provide the deep horn insemination technique when necessary. The deep horn insemination is a special insemination technique that allows deposition of the semen very close to the ovary that is releasing the egg. Therefore, the amount of semen used for insemination can be decreased. Deep horn insemination can increase pregnancy rates of subfertile stallions and stallions with a low sperm number. Treatment protocol will be established on an individual basis to optimize the chances of a viable pregnancy. New infertility treatments and medications can be discussed with Dr. Martinsen in advance. A full Embryo Transfer service is also available for mares that are not able to become pregnant or carry a foal to term.

Insemination with Fresh Semen

Stallions are collected at Bella Vista Equine or at local farms. The semen is checked immediately for motility and concentration and diluted with an appropriate extender. The extenders contain substances that improve quality and survival time of the semen and increase the chance of conception. Stallions with poor semen quality and some problem mares, daily insemination with fresh semen is applicable.

Insemination with Cooled Semen

The farm manager where the stallion is located is informed that the mare is being monitored at Bella Vista Equine. We require a current negative EVA test from the stallion before the semen can be shipped to Bella Vista Equine. Information regarding collection schedule and semen quality is gathered in advance to optimize synchronization of semen shipment with mare ovulation. If we are informed that the quality of the semen is not adequate for next day delivery than we will make arrangements for same day pick up at the airport. Semen shipment will be ordered when the mare has a mature follicle associated with uterine edema and cervical relaxation. Not every mare will show signs of heat at the time of breeding, and therefore ultrasound and palpation expertise is crucial at this time. The size of the follicle at the time of breeding may vary between mares and different horse breeds. For example, Arabian mares tend to ovulate smaller size follicles than Friesian mares. We will make all efforts to order semen via Fedex or UPS for overnight delivery, however under special circumstances same day shipments are required. We will be able to provide a courier for semen airport pickup if necessary. When semen arrives at Bella Vista Equine, concentration and motility are immediately estimated. Pregnancy rates are optimized when insemination occurs within 24 hours pre-ovulation or within 6 hours post-ovulation.

Insemination with Frozen Semen

The longevity of frozen/thawed semen is shorter than fresh or chilled semen. Therefore, insemination needs to be performed as close as possible to ovulation. In some cases, stallions can impregnate mares inseminated 24 hours prior to ovulation. However, better results are obtained if insemination occurs within 12 hours prior to ovulation and/or within 6 hours post ovulation. Frozen semen inseminations at Bella Vista Equine are performed within 6 hours from ovulation, and in most cases within 4 hours from ovulation. Timing insemination as close as possible to ovulation is the key success for a high pregnancy rate. Bella Vista Equine is proud to offer convenient frozen semen services. Dr. Martinsen resides on the premises and the mares are monitored and inseminated 7 days a week. The Deep Horn insemination technique is used in all mares bred with frozen semen. Not every mare is a good candidate for frozen semen insemination. Some mares bred with frozen semen may have a reaction and develop uterine inflammation and/or uterine fluid. We try to minimize inflammation by breeding our mares post ovulation with only one insemination dose. The mares are checked 12 to 24 hours post breeding and treated if signs of inflammation are present. The frozen semen can be shipped well in advance in the beginning of the breeding season and stored at Bella Vista Equine. The clinic offers permanent semen storage. We encourage our clients to obtain information about the quality of the semen they intend to use for their mares, including post-thaw motility and number of sperm per insemination dose. Knowledge of the stallion pregnancy rates with frozen semen prior to purchase of the frozen semen is very important and it will usually set the expectations for the upcoming breeding. Bella Vista Equine will only accept frozen semen from EVA negative stallions.

Embryo Transfer Services

Bella Vista Equine offers full Embryo Transfer Services. Dr. Martinsen has more than ten years of experience in the area. Please refer to the Embryo Transfer Brochure for more information.

Foaling Services

Foaling Services are provided to mare owners that intend to breed their mares at Bella Vista Equine after foaling. We use the foal alert system to monitor Foaling. This system contains a small device which is attached to the vulvar lips a few days before the mare’s due date. Upon foaling, the device will transmit a signal to an automatic dialer that notifies the veterinarian on call. The mare is monitored until she passes the placenta and the foal stands up for nursing. We supervise nursing frequency for the first 24 hours and perform a blood test on the foal to determine if colostrum intake has been adequate.

Breeding Soundness Exam

Prior to the beginning of the breeding season a Breeding Soundness Exam should be performed in all stallions intended for transported semen. The exam should include semen concentration, motility, morphology and cultures in addition to test cool. The size and consistency of the testicles are also measured and the results recorded for future reference. An EVA test is also performed in all stallions intended for breeding. Stallions with poor semen quality receive special management in order to maximize pregnancy rates. Deep horn insemination performed at Bella Vista Equine allows insemination of mares with stallions that have a low sperm number without a significant decrease on the conception rate.

Test Cool

During the test cool, the semen is diluted with different extenders at different concentrations and the motility is evaluated immediately after collection as well as 12 hours, 24 hours and 48 hours later. According to the test cool we can determine the best extender and the best concentration ideal for the semen shipments. Extenders provide nutrients, antibiotics and protection against the variation in temperature during semen transport. The volume of extender added to the semen has to be at least twice the volume of the semen. The volume of the extender is very important. If the semen dose is too concentrated, then it will lack protection and nutrients and the quality of the semen will be poor 24 hours later.

Shipped Semen

On average, the semen dose shipped should be at least 1 billion in order to account for the abnormal, non-motile sperm at the time of insemination. Stallions are usually collected on Monday, Wednesday and Friday, unless special arrangements are made in advance. Semen shipments should be requested by 9 AM Eastern Time on Monday, Wednesday and Friday, the day of the collection, for all Fed-Ex shipments. Requests for same day shipments need to be made 24 hours prior to regular collection days. We do not guarantee same day services to all locations since the airlines we use may not service all areas.

Frozen Semen

Many breed registries are now accepting frozen semen inseminations. The advantages of frozen semen are numerous. Stallions can produce foals while they are at shows, performance events or recovering from an injury. The breeding market can be extended to include overseas transactions. The breeding season can be prolonged all year around considering the difference in the seasons in the northern and southern hemispheres. Semen from valuable stallions can be saved as insurance for future use after the death of the stallion. Once the semen is frozen and stored properly, its characteristics remain indefinite.

Processing Frozen Semen

Frozen semen results vary among stallions. Some stallions have excellent semen quality after freezing while others have very poor results. Different freezing extenders and freezing methods can influence the quality of the frozen semen. The first step in the process is to perform a test freeze. Semen is collected from the stallion and analyzed for volume, concentration, motility, and morphology. If the semen quality is adequate, the freezing process begins. Several different freezing extenders and methods are used to determine which extender/method will result in better semen quality after thawing. The semen is diluted with a milk base extender and centrifuged. Centrifuging the semen separates the sperm from the remainder of the ejaculate. The supernatant is removed and discarded. The pellet containing the sperm is diluted with several different types of freezing extenders. The solution containing the sperm is packed in straws. At least two different freezing techniques are tested. First, the semen is frozen in the nitrogen vapor and then immersed in liquid nitrogen. The straws are placed in large nitrogen tanks and stored until they are used. One straw from each different freezing extender and method is thawed and the motility analyzed and compared. If results are favorable then further semen collections are performed. If results are unfavorable then the freezing technique is adjusted and the semen re-tested. Some stallions will just not freeze well regardless of the technique and their semen should in these cases not be used frozen. Several insemination doses or straws are obtained per semen collection. An average collection can yield 10 to 15 doses of frozen semen, but it can vary from 2 to 18 doses.

Frozen Semen Inseminations

We recommend testing the frozen semen in a few young fertile mares before banking large quantities of semen. Inseminations have to occur as close as possible to ovulation to optimize the results. The mare must be checked several times during the estrus cycle so we can determine precisely when ovulation occurs. Inseminations with frozen semen are performed within 6 hours from ovulation. A maximum of two doses of frozen semen are used per cycle.

Bella Vista Equine Services offers high quality embryo transfer (ET) services. The technique developed more than two decades ago has evolved into a well accepted and successful procedure. Many horse registries accept embryo transfers, however, you should first contact your horse registry to get an update on their regulations before considering this procedure.

Embryo transfer has many advantages. It allows the production of foals from older sub-fertile mares and from mares that foaled late in the year. High performance mares can produce foals while they are still in training. Occasionally, more than one foal can be obtained from a single mare in a given year.

The success rate of embryo transfer is dependent upon many individual components. For example, age and fertility status of the donor mare and recipients, stallion semen quality, synchronization of both donor and recipients, and handling of the embryo after recovery. In general, the success rate of ET is around 70 - 75%. Sub-fertile mares may require treatment before entering the program to maximize the success rate. Dr. Elizabeth Martinsen can evaluate your mare on an individual basis to give you a better prediction of results.

Embryo Transfer Technique

The donor and recipients are monitored daily at Bella Vista Equine. At least two recipient mares will be synchronized with each donor mare. The donor is bred as close as possible to ovulation to increase the chances of fertilization. Ovulation timing is also important in order to schedule the day and time for the embryo flush. This should occur 7 to 8 days after ovulation. During embryo recovery, several liters of a special solution are placed inside the donor's uterus and the flush is recovered through a special cup containing an embryo filter. The filter allows separation of the embryo from the fluid recovered from the uterus. The cup containing a small amount of this special solution is transferred into a search dish. The dish is placed under the microscope and the embryo is searched.

Once the embryo is found and determined to be healthy, it is transferred to other dishes containing a holding solution. The embryo is "washed out" of any debris. The embryo is manipulated carefully and placed inside a special embryo transfer pipette. The recipient mares that were synchronized with the donor are palpated and ultrasound performed to determine the recipient that best meets the criteria for the embryo transfer. The recipient mare is prepared and the vulvar area is cleaned for the procedure. The embryo is deposited into the recipient mare's uterus.

Following the embryo transfer, the recipient starts receiving injectable progesterone. The first pregnancy check occurs at 14 days (6 days after the embryo transfer, since the embryo was 8 days old at that time). The recipient is then checked at 25 days for a heart beat and again two weeks later. The recipient mare can be released from Bella Vista Equine after the 45 day pregnancy check. Please refer to the contract for additional requirements that need fulfilled prior to release of recipient mare.

Recipient Mares

Recipient mares are provided by Bella Vista Equine. We will synchronize at least two recipient mares per donor mare in case one of the recipients fails to have a normal cycle. The recipient mare can ovulate a day prior, the same day or up to 3 days after the donor mare. However, just prior to the embryo transfer, the recipient mare will undergo another selection. Based on palpation and ultrasound of the ovaries, uterus and cervix we will determine the recipient that has the best uterine and cervical tone and is the best candidate to receive the embryo. Choosing a good recipient mare at the time of the transfer is crucial for the success rate. Recipients are usually young (less than 10 years old) and free of any reproductive pathology.

Foaling Services are provided to mare owners that intend to breed their mares at Bella Vista Equine after foaling. We use the foal alert system to monitor Foaling. This system contains a small device which is attached to the vulvar lips a few days before the mare’s due date. Upon foaling, the device will transmit a signal to an automatic dialer that notifies the veterinarian on call. The mare is monitored until she passes the placenta and the foal stands up for nursing. We supervise nursing frequency for the first 24 hours and perform a blood test on the foal to determine if colostrum intake has been adequate.

The following article was presented in Horses Magazine April 2009:

Prior to foaling:

Caring for the newborn foal starts with the broodmare care. Appropriate nutrition and pre-foaling vaccinations of the broodmare are crucial in producing a healthy foal. The pregnant broodmare should receive her pre-foaling shots 4 to 6 weeks prior to the mare’s due date to ensure appropriate level of immunity in the colostrum. Bella Vista Equine* does not recommend the administration of modified live vaccines to any pregnant mares. If you plan to move your mare to a large breeding farm for foaling, you may be required to give additional pre-foaling vaccinations to protect the mare and the newborn foal against organisms that may be common in large breeding farm operations. You should always discuss with your veterinarian about the pre-foaling vaccines recommended for your region.

At foaling:

Foaling frequently occurs during the early morning hours. Farm personnel should be observant and call a veterinarian for assistance if a problem arises. Intervention by the owner or farm personnel may be necessary and the level of intervention depends on the handler’s experience. Too much intervention during a normal foaling could be detrimental to the mare and foal. It is important to understand the normal turn of events so that you can recognize any problems early on. Foaling is divided into 3 stages. During the first stage the mare will have uterine contractions that will position the foal and move it towards the birth canal. This stage lasts between 1 to 2 hours and sometimes may go unnoticed by the observer. The fetal membranes will be visible and the sac breaks initiating the second stage. The mare starts delivering the foal during the second stage. If the mare does not progress delivering the foal during this second stage or if the delivery lasts more than 30 minutes then you must call your veterinarian. Should you suspect that the position of the foal is abnormal, such as hoof soles in the upward position or only seeing one front leg at delivery, you need to immediately call in your veterinarian. After the delivery of the foal, the third stage of labor begins. During this stage the placenta will be expelled. Expulsion of the placenta may take up to 3 hours. Any delay beyond this point is a concern. Another worry is “redbag”. A “redbag” may occur during foaling, when the placenta separates from the uterus prematurely and the oxygen supply of the foal is compromised. During the course of a “redbag” delivery, the mare starts foaling with the intact red bright placenta attached to the foal and covering the foal’s airways. If the mare is presented with a “redbag” at foaling then direct intervention is necessary. The foal may die asphyxiated if the placenta is not broken on time and if the foal is not delivered immediately. However, some foals may look normal for the first 12 to 24 hours only to turn into dummy foals 36 hours post-foaling. “Redbag” foals should always be examined by a veterinarian. It is not recommended to cut the umbilical cord with scissors since it can cause excessive bleeding of the umbilical stump. The umbilical cord can be left alone or separated manually by holding it firmly with 2 hands and twisting and pulling on it, so that it breaks about one inch from the foal’s abdomen. After the umbilical cord is ruptured, the blood vessels will shrink and it should stop bleeding by itself. Tying the cord is not recommended. By tying the cord you may prevent the natural closure of the blood vessels and predispose the umbilical stump to infection. Assuming a normal foal delivery and everything appearing normal, allow the mare and the foal time to bind alone.

First 24 hours:

If the foal seems weak and not acting normal you should contact your veterinarian. A normal foal will stand and move around within the first 2 hours, and by 3 hours it should have located the teat and have nursed. Foals that fail to locate the teat and don’t nurse within 3 hours will need some assistance. It is highly recommended to administer a foal enema to every foal as soon the foal is able to stand. At times foals refuse to nurse just because they have not passed enough meconium (first dark stool), even without showing obvious signs of a meconium impaction. Bottle feeding the foal with the mare’s colostrum or frozen colostrum may be an alternative if the foal fails to nurse on its own within the first 5-6 hours from foaling. At this time you should contact your veterinarian for advice. The foal may require tube feeding with colostrum by your veterinarian if it fails to nurse by 8 hours from foaling. The goal is to have adequate colostrum intake before the first 12 hours. The volume of colostrum necessary for the first 12 hours depends on the quality of the available colostrum and the size of the foal. Normally, a volume intake of 1,000 ml of colostrum in the first 12 to 16 hours is adequate. At birth, the foal’s intestinal cells are able to absorb the large immunoglobulin molecules from the colostrum. However, after 12 hours there is very little or maybe no absorption of colostrum. This is why early intervention is important! Intake of colostrum during the first 24 hours is also important to protect the foal’s intestine against diarrhea. Commercial colostrum sold in stores should only be used as a supplementation and not as a replacement of colostrum. Colostrum from other species will not provide adequate immunity to newborn foals. The newborn foal is immunologically naive at birth. The placenta of the mare does not allow the transfer of large immunoglobulin molecules that would provide resistance to infections. Therefore, the newborn foal needs the colostrum intake in order to obtain the immunoglobulins to fight any infections. A foal that fails to obtain the passive immunity from the mare is at risk of becoming sick and may eventually die. A very simple blood test can be performed by your veterinarian when the foal is 16 -24 hours old to check for adequate colostrum intake. Foals that have failure of passive transfer or poor colostrum intake can be treated by receiving a plasma transfusion. Leakage of colostrum prior to foaling can also affect the quality of colostrum intake by the foal and it should be discussed with your veterinarian. Navels are treated every 8 hours for the first 24 hours. It is recommended to dip the navel with either a diluted 0.5% chlorhexidine solution (the number one choice) or a diluted betadine solution while avoiding strong iodine preparations. If iodine is the only solution available then you need to make sure that the solution is 2% diluted iodine. Stronger iodine solutions are likely to cause burning and necrosis of the navel and predispose navel infection and patent urachus (urine dripping from the navel). Remember that newborn foals don’t roll. If the newborn foal is rolling, switching the tail, or positioning the legs flexed when lying down and restless a likely cause is colic. The most common cause of colic in the newborn foal is meconium impaction. The meconium impaction can occur up to 24 hours from foaling even if the foal has already passed some meconium. Signs of colic in the newborn may also be a sign of a ruptured bladder or a discomfort that precedes diarrhea. If you notice any signs of discomfort in your foal do not hesitate calling your veterinarian for care instructions.

After 24 hours:


To prevent complications a foal navel should be checked regularly. A wet navel after the foal is more than 48 hours old is a worrisome signal and you need to contact your veterinarian. Watch the newborn foal frequently to see if it is bright and alert. The foal should constantly nurse and is often followed by a nap. Foals that wonder off and that are not interested in nursing can be a concern. If the foal is not nursing, the mare’s udder may remain full. Always check the mare’s udder to see if the foal is consuming enough milk. Be concerned when the mare’s udder is too full or too small. Mares that do not produce enough milk will have udders that are frequently small in size. In these cases the foal will be back to nurse too often and it may also skip nap time. You may think that the foal is nursing well when in fact it is seeking the mare non-stop because it is hungry. Some newborn foals have weak legs and are down in the pasterns. The legs should become stronger with time. If you notice any limb deformities in the newborn contact you veterinarian to discuss any treatments or recommendations for the condition. When the foal is about 10 to 14 days old it may present diarrhea associated with the mare being in heat (foal heat diarrhea). Generally, this type of diarrhea does not require any treatment. Diarrhea in the newborn that is not associated with the mare’s foal heat should be discussed with your veterinarian and treated accordingly. Newborn foals from mares that receive the appropriate foaling shots require no additional vaccinations. In this case the first vaccinations can be performed after 3 to 4 months of age. Foals can obtain their first wormer at 30 days. Finally, always keep the lines of communication open with your veterinarian and take the time to ask when you are in doubt. Foaling and taking care of the newborn foal is a worrisome period but after a few foaling experiences you will become familiar the foaling process. Soon you will be able to start enjoying your new additions instead. *Bella Vista Equine is a specialized reproductive clinic located in central Ohio that provides breeding and management of problem mares, complete embryo transfer services, on-site foaling facilities and comprehensive stallion work-up.

In addition to specialized reproductive services Bella Vista Equine also provides general veterinary services. We perform routine on-farm calls in Central Ohio extending as far as fifty miles from our clinic. General services we offer to clients include routine equine medicine such as vaccinations, de-worming, general herd health management, teeth floating, sheath cleaning, lacerations and wound management, colic services and minor surgeries such as castrations.

Emergency services are by nature offered closer to home and in most cases for our existing clients only. We would like you to know that due to the busy case load that we encounter, especially during the breeding season, our general and emergency services may be limited to in-house work only. Due to the large geographical area that we cover we suggest that you seek veterinary emergency assistance that is close to your location ensuring the best medical outcome for your horse.

Primary emergency treatment facility in Central Ohio:
The Ohio State University, College of Veterinary Medicine, emergencies: (614)292-6661