New products and novel techniques are designed to make life easier for breeders

THE TRADITIONAL approach to breeding Thoroughbreds often puts the industry at a disadvantage when compared with breeds that allow artificial insemination.

Demanding use of live cover to accomplish conception prevents Thoroughbred breeders from using technology, such as embryo transfer and in vitro fertilization, which has helped drive up conception rate in other breeds.

Yet, researchers who are dedicated to helping the Thoroughbred breeder continue to develop better breeding practices, more effective products, and enhanced neonatal care. Here are some advances in reproductive technology that have occurred recently.

Solution for 'dirty' mares

A class of drugs called immunomodulators is showing promising results in fortifying a mare's immune system to naturally destroy Streptococcus, a bacteria that causes inflammation of the lining of the uterus. Called endometritis, the condition often affects a mare's fertility by preventing her from conceiving or causing her to lose the fetus in early gestation if she does become pregnant. Persistent, unchecked endometritis also can cause scarring and degenerative changes in the uterine lining.

According to Lisa Turney, who, with her husband, Tim, owns Shamrock Glen Farm in Versailles, Kentucky, Grade 2 winner Sun King would not exist if his dam, Clever But Costly, had not been treated with Settle, the first immunomodulator to be approved by the United States Department of Agriculture as an aid in the treatment of endometritis caused by Streptococcus zooepidemicus. Settle is produced by Bioniche Animal Health USA, a biopharmaceutical company based in Bogart, Georgia.

According to John Steiner, D.V.M., a fertility specialist at Hagyard Equine Medical Institute in Lexington, a similar product has just finished favorable clinical trials.

"Settle and [the] product [we studied] work in a similar fashion, but we don't know exactly how they work," Steiner said. "In the study just completed--a randomized, double-blind clinical trial using over 100 mares and only mares that had endometritis--we had positive results. We're putting the final touches on our paper, which has been submitted for the International Symposium on Equine Reproduction meeting next year."

No-foal nurse mare

Peter Daels, D.V.M., Ph.D., a reproductive specialist at Institut National de la Recherche Agronomique in France, has discovered a way to turn a barren mare into a nurse mare by giving her a combination of progesterone and sulpiride. Progesterone is found in Regu-Mate; sulpiride, which is used to treat psychosis in humans, is similar to domperidone, a drug widely used in the horse industry to prevent fescue toxicosis and to increase milk production in foaling mares.

Nurse mares are needed when one or more situations occur:

• A foal is orphaned or is separated from its dam when the mare must be hospitalized;
• The dam is unable or unwilling to nurse the foal;
• The mare's temperament makes it unsafe for the foal to remain with her; or
• The broodmare must be transported a long distance to be rebred, and the trip would be detrimental to the foal.

Traditionally, those who provide nurse mares to the breeding industry keep a band of mares--often large ponies or draft horses--that are impregnated solely to produce milk. When one of these mares foals, the baby is taken from her and the mare is delivered to a breeding farm that needs her to nurse one of its foals. At weaning, the breeding farm returns the nurse mare to her owner in foal for the next breeding season.

Nurse mares are not cheap to lease. Moreover, the trauma--both emotional and physical--suffered by the unwanted foals these nurse mares produce each year is a skeleton in the closet of the breeding industry. Daels's discovery could eliminate both problems by allowing breeding farms to use one of their barren mares for the job.

In his study, Daels selected nonpregnant mares that had produced at least one foal during their lifetime and administered progesterone and sulpiride to them for ten days to stimulate adequate milk to sustain a foal. Once the foal began to nurse, the mare continued to produce milk until the foal was weaned.

According to Daels, for the first month a foal was on a barren nurse mare, the youngster did not gain as much weight as its naturally nursed counterpart, but by the end of the second month, it was of normal weight.

Colostrum refractometer

A foal must ingest colostrum, the yellowy substance in a mare's first milk, within 24 hours of foaling to acquire protection against disease. Antibodies that concentrate in the mare's milk in the days leading up to foaling are absorbed into the foal's gut when it nurses. From there, antibodies pass into the foal's circulatory system where they establish immunity to diseases the mare has been exposed to or vaccinated against in the last trimester of pregnancy. This is called passive transfer.

The concentration of antibodies in colostrum gives it a waxy appearance. This is why a mare that is ready to foal is said to be "waxing up" as colostrum begins to concentrate in her udder and forms a waxy deposit on her teats.

A mare produces a limited amount of colostrum, and not all mares produce colostrum that is rich enough in antibodies to pass immunity to the foal. Without adequate passive transfer, the foal quickly may become a victim of the pathogens in its environment, a life-threatening situation.

Meters to measure the quality of colostrum have been available for years, but they typically were desktop units kept in the veterinarian's laboratory. Animal Reproduction Systems has introduced a small, portable unit that is inexpensive enough even to be included in a small farm's foaling kit.

A few drops of the mare's colostrum are placed in the meter. Then the foaling person holds the meter up to his or her eye like a telescope to view the thermometer-like gauge inside. The colostrum quality registers "poor," "fair," "good," or "very good" on a vertical scale. Knowing the quality of a mare's colostrum within minutes of testing gives the farm manager ample time to notify the veterinarian of the problem, obtain donor colostrum for the foal, or purchase plasma to fortify the foal's immune system if frozen colostrum is unavailable.

The colostrum refractometer also can be used to identify mares with good quality colostrum for banking.

Combination IgG and sperm meter

Another portable appliance called a densimeter, also manufactured by Animal Reproduction Services, is a device that measures the level of immunoglobulins (IgG) in a foal's blood to assure it has received adequate passive immunity. This unit is designed for the experienced foaling manager, farm veterinarian, or veterinary technician on a commercial breeding farm because it uses blood drawn from the foal for the test.

The initial test is performed at 12 hours of age and takes ten minutes to produce results.

The unit, which is small enough to fit in one's hand, is powered by nickel metal hydride and nickel cadmium batteries, similar to those in a laptop computer, and it has a built-in battery charger.

Other less expensive tests for foal IgG are on the market, but this unit is unique because as a kit, it can be adapted to become a sperm counter for use in the stallion side of the farm's operations.

Using the sperm counter, the farm can monitor the fertility of its stallions and monitor the effectiveness of treatment for fertility problems.

Breeder-friendly equipment

Animark Inc. has produced an ultrasound unit that breeders can use to detect pregnancy in a mare as early as 14 days after conception. Unlike ultrasound units used by veterinarians, the Pregscan wand is placed externally on the mare's flank. Pregscan is precalibrated by the manufacturer to recognize the tissue change caused by conception. The Pregscan display automatically shows if the mare is in foal or not.

The test takes two minutes to complete, and Animark claims it is 98% accurate and can be performed as often as the breeder wishes, until the foal is born.

Another Animark product is the ovulation predictor, a probe the breeder can insert into the mare's vagina that samples the moisture on the tissue to detect any changes that are precursors to ovulation. Readings are displayed on an LCD (liquid crystal display) display. According to Animark, ovulation can be predicted as far as five days ahead.