Dr. Corey Miller is the director of the reproductive department at Equine Medical Center of Ocala. Dr. Miller, Dr. Phillips and Dr. Benker provide hospital-based and ambulatory services to local breeding farms and haul-in clients. Dr. Miller is a board-certified specialist as certified by the American College of Theriogenology (reproduction). Our comprehensive, specialized array of reproductive services include stallion reproductive services, mare reproductive services and imported frozen semen.

  • Stallion fertility evaluations
  • Collection of semen for freezing and cooled transport
  • Mare evaluations
  • Management of mares for breeding with cooled and frozen semen
  • Embryo transfer and vitrification (freezing)
  • Management of the sub-fertile mare and stallion

We welcome you to contact us at Equine Medical Center of Ocala to discuss your case and our ability to offer a specialized course of treatment for your mare or stallion.

Corey D. Miller, DVM, MS, Diplomate ACT
Cell (352) 266-7828

Fred W. Benker, DVM
Cell (352) 362-0866

Justin Phillips, DVM
Cell (352) 266-1720



Stallion reproductive evaluations are performed for a number of reasons. Examination of a breeding stallion may be a prelude to the breeding season or prior to purchase. Additionally, a reproductive evaluation is done to assess damage after an injury or if a fertility problem is suspected. A stallion evaluation includes the collection of semen and evaluation for volume, motility, concentration and total sperm numbers. To assess potential pathogenic bacterial growth, a set of cultures is taken from the prepuce, urethra, and semen. In addition, spermatozoal morphology is assessed to determine the structural integrity of the sperm cells. Lastly, the stallion’s testicles are evaluated by palpation and ultrasound for consistency, conformation, orientation and size. Once all results are gathered, a full report that provides descriptive details of the findings is provided to the stallion owner. The report makes recommendations on breeding procedures, treatment of any bacterial pathogens, and the general suitability of the horse as a breeding stallion.


A breeding phantom is a man-made object that a stallion mounts so semen may be collected. Use of a phantom not only eliminates the need for the stallion to mount a mare in heat, but also reduces the potential for injury and disease transmission. Most stallions can be trained to use the phantom within a short period of time. We have an adjustable phantom in our breeding room, which has cushioned, non-slip rubber flooring. Because of its adjustability, the phantom can be tailored to fit various-sized stallions as well as those with injuries that prevent them from properly mounting.

We also accept breeding stallions with behavioral issues that prevent them from breeding efficiently or that cause the stallion to be dangerous to handlers, mares, or themselves. Examples include any of the following undesirable behaviors: sour attitude, over aggressiveness, self-mutilating behavior, slow breeding, inconsistent performance, inadequate erection, failure to ejaculate, and mounting dysfunctions. These and other issues can be evaluated and corrected in most cases, normally by changing methods of handling or managing the stallion. Attempts will be made to retrain and/or find a management scheme that will allow the stallion to be functional at the farm again.


The Equine Medical Center of Ocala provides a cooled semen program that allows stallion owners to offer cooled, transported semen for their breeding operation without needing the knowledge, skills and equipment to do so. Our staff will collect semen from your stallion and ship it to desired locations throughout the United States and Canada. For same-day service, semen can be collected in the morning, delivered by a courier to Orlando International Airport and shipped via airlines to the city/airport of choice. Next-day delivery is routinely done utilizing Federal Express.

Initially, we recommend that each stallion entering a cooled-shipped program be tested with various semen extenders that contain different antibiotics to determine which antibiotic and extender works best for a particular stallion to optimize spermatozoal longevity. This test is performed by collecting semen and storing semen samples at cooled temperatures for up to 48 hours in different semen extenders. Once there is a firm understanding of semen longevity, then recommendations are made as to the best method of shipping the semen, including dilution ratios and the type of extender to use.
With minimal advanced notice, owners can trailer their stallion to our facility, have semen collected, and take the stallion back home while the semen is processed for shipment. Although it is desirable to have stallions trained to the phantom, we do provide jump mares for untrained stallions.


The Equine Medical Center of Ocala offers a semen freezing service for those horse owners looking to expand their breeding program and/or preserve their stallion’s ability to produce offspring even after injury or death. The first step taken is to determine whether the stallion is a good candidate for semen freezing. This determination is based on the findings from a full reproductive evaluation and test freezing. Our freezing program is based on the programmable-cell freezing method utilizing different protocols, including three different types of extenders. If an acceptable protocol is achieved, the stallion is collected every other day and the semen processed and frozen until the desired number of breeding doses is obtained. The frozen semen is cryogenically preserved in a tank filled with liquid nitrogen which maintains a temperature of -196° Celsius.

Frozen semen can be stored at our facility for a monthly fee or shipped to any destination within the United States. For shipping purposes, the frozen semen is packaged in a dry shipper charged with liquid nitrogen which maintains an adequate temperature for 7 to 14 days.

If a horse owner desires to export frozen semen from their stallion to countries other than the U.S. or Canada, the Equine Medical Center of Ocala is a USDA-approved quarantine and collection facility for the export of frozen semen. In this case, the stallion will need to be boarded and quarantined at our facility according to the requirements of the countries to which the semen will be exported.



Similar to a stallion evaluation, a mare reproductive evaluation is very important when a mare has a poor reproductive history, is being purchased with the intent of breeding her, or has had a previous dystocia (difficult birth) that may have caused trauma to the reproductive tract. It is not uncommon for mares to have underlying problems that were previously undetected. If a mare has any history of fertility problems, a full evaluation may detect a reason for the subfertility and help to better understand the future chances of getting her in foal and maintaining a pregnancy. In an attempt to recognize potential complications, many breeders elect to have a reproductive evaluation done before the breeding season. Certain management schemes can be put in place to help sustain a pregnancy if issues are detected early.
The mare reproductive evaluation at the Equine Medical Center of Ocala includes an examination of the perineal (vulvar) region; palpation and ultrasonography of the reproductive tract; vaginal speculum examination; and culture, cytology and biopsy of the uterus. Shortly after the results are compiled, a full report is provided to the mare owner describing the findings and making recommendations with regard to treatment, breeding procedures, and suitability of the mare for breeding.


The technique of passing an embryo from one mare (donor) into another mare (recipient) has become a viable option for many horse owners. This procedure enables older, genetically superior mares that no longer have the uterine competency to maintain a pregnancy to continue to produce offspring by transferring their embryo into a younger, reproductively sound mare. It can also be utilized when a foal is desired out of a competition mare who can’t be given time off to have a foal on her own or when multiple foals are desired out of one mare the same year, either by the same or different stallions.
After standard breeding procedures, the donor mare needs to be transported to the Equine Medical Center of Ocala 7-8 days after ovulation for embryo recovery. This procedure involves lavaging the mare’s uterus with specialized flushing media and running the fluid back out of the uterus through a filter that will trap the embryo. The embryo can be transferred directly into another mare, can be shipped to a distant location for transfer into a recipient mare, or it may be vitrified (frozen) and stored until the owner wishes to transfer it into another mare.


Artificial insemination has become common place in the equine industry, but without proper training and experience, the breeding process can still be rather intimidating to many horse owners and veterinarians. Our reproductive staff is available to work with your mare either at your farm or in our facility. If the mare is brought into the clinic, we evaluate follicular growth, determine the optimal breeding time; order, evaluate and inseminate the semen, and perform post-breeding uterine lavage and antibiotic infusions.


Because frozen semen has a shorter lifespan in the mare’s reproductive tract when compared to fresh or cooled semen, it is essential for frozen semen to be inseminated as close to ovulation as possible. To optimize pregnancy rates, mares should be examined for follicle development several times throughout the day and night (every 5-6 hours). As one could imagine, this becomes very impractical for most veterinarians on the farm. The management program at the Equine Medical Center of Ocala allows mares to be checked for ovulation at least four times per day when ovulation is imminent.
The result is a more accurate prediction of ovulation and insemination timing, and therefore a higher pregnancy rate per cycle. Additionally, a technique called deep-horn insemination is routinely employed to place the thawed spermatozoa in closer proximity to the site of fertilization, rather than just the standard uterine body. Use of this procedure is particularly important if a low dose of frozen semen is being used or if the stallion’s frozen-thawed semen is not of good quality.


For inexperienced or concerned mare owners, we offer a service where mares are boarded at our facility so that experienced staff is on site 24 hours a day to attend and, if necessary, assist in the foaling process.


For mares that are foaling and are having difficulty passing the foal, we offer 24-hour emergency service to help the mare extract the foal. In most cases, we are able to deliver the foal vaginally by anesthetizing the mare and changing the foal’s position. However, there are instances when we are forced to do a Caesarean section to deliver a live foal.


The staff at the Equine Medical Center of Ocala is experienced in the breeding management of mares that have a history of abortion, early embryonic death or failure to conceive. The best chances for a sustained pregnancy may only come when these mares undergo very detailed management practices. Routine ultrasound examinations are very important when assessing ovarian or uterine characteristics. Close attention is paid to follicle growth patterns, impending ovulation, uterine edema, cysts, fluid retention within the uterus and insemination frequency and volume. Management of these mares may include minimizing inseminations, performing uterine lavages and infusions with antibiotics, and administering hormonal treatment.


Mares can have conformational problems that limit their ability to produce a foal. Although some mares are born with poor conformation (such as a mare that pools urine in the vagina, in which case a urethral extension is needed), many times a difficult foaling will create lacerations that need to be repaired before the mare can maintain a pregnancy again. The staff at the Equine Medical Center of Ocala is able to evaluate and repair these problems. Mare reproductive surgery includes urethral extensions, perineal laceration repair, cervical laceration repair and ovariectomies.


We are the exclusive agent for imported frozen semen from over 20 horse and pony stallions from Britain and Ireland. This section of the department is managed by Christine Miller, who is responsible for all aspects of the marketing and distribution of the semen throughout the United States and Canada.

Visit the website at for more information about these stallions.

Christine Miller
(352) 266-4669

Equine Medical Center of Ocala offers a premier equine hospital facility and the best team of boarded internists and boarded surgeons in the Southeast United States. EMCO can handle all of your horse healthcare needs and provide you with the best service in the industry. We provide direct service as well as referral service, and we pride ourselves on our relationship with our referring veterinarians.