Uterine Tubal Patency Examination

Breeding is big business. Those who doubt need only look at the results of the 1998 Keeneland November breeding stock sale for verification. Prices for broodmares and weanlings soared--top price for a broodmare, $7 million; for a weanling, $1.5 million. That sale merely continued a trend developing over the last few years in one segment of the horse industry.

If the Thoroughbred sales can be used as a barometer for the horse business in general, then all breeds are affected by the upsurge in prices obtained for horses sold at auction or sold privately. With more disposable income at hand, consumers are willing to spend money on items that help fill their leisure time. Horses, no matter the breed or the discipline, are at a greater demand than ever.

It is little wonder that getting a mare in foal and producing a healthy offspring are of prime importance. These goals often are not easily achieved. There are many points along the journey where missteps can occur.

To begin with, it is not always easy to get a mare in foal. As the producing mare ages, the cumulative wear and tear on her reproductive system might lead to problems that prevent conception. If this mare is a high-quality producer, her failure to conceive and produce a live foal results in an economic loss, the effects of which last for more than a year or until the next time she can conceive and foal. Therefore, the more a breeder can do to learn about his or her mare's possible problems before the breeding season begins, the more can be done to overcome those problems and ensure that the mare conceives and produces a healthy foal.

One of the first places that a problem can occur is within the mare's reproductive system, an intricate series of interrelated parts that must function together. The ovaries are the areas of the reproductive system where the eggs are produced. Shaped like kidney beans, the ovaries have the ability to enlarge, as they do when the mare is in a period of sexual activity (estrus), and to shrink, when the mare is in a period of sexual inactivity (anestrus).

Another prime piece of reproductive real estate is the uterus, which is shaped like the letter Y. It is there that the fertilized egg matures. Once the fertilized egg moves into the uterus, it spends several days moving around the uterus before finally attaching itself, usually at the base of one of the two uterine horns (the V shape part of the organ). Research has shown that this movement signals to the mare not to begin her cycle again, and thus protects the pregnancy. After attachment, the uterus houses the developing fetus, providing nutrition and protection.

Located between the ovaries and the uterine horns and connecting the two are the uterine tubes, also known as the fallopian tubes or oviducts. These, too, play an important role in reproduction, for it is here that the egg is fertilized. Hair-like projections (cilia) line the oviducts, and their beating motion aids the movement of the egg toward the uterus and the movement of the sperm toward the egg. When egg and sperm meet within the uterine tubes, conception occurs.

It sounds simple enough, but trouble spots abound, and the uterine tubes are one such area. Abnormal conditions (pathologies) of the uterine tubes might prevent the egg and sperm from joining together. For example, a blockage might exist that would prevent the egg from completing its journey or prevent the sperm from reaching the egg.

Therefore, being able to determine the patency (condition of being widely open) of the uterine tubes is invaluable in combating infertility in mares. However, the process of determining uterine tubal patency is not an easy one, nor is it inexpensive.

Researchers at the University of Virginia, including William B. Ley, DVM; John M. Bowen, BVetMed; Beverly J. Purswell, DVM; John J. Dascanio, VMD; Nikola A. Parker, DVM; and Thomas L. Bailey, DVM, investigated a technique that was both less costly for the owner and less invasive to the mare. Their findings were presented at the 1998 AAEP Convention in their paper "Modified Technique To Evaluate Uterine Tubal Patency In the Mare."

The technique uses an ultrasound to guide the depositing of fluorescent microspheres over the surface of the ovary. The procedure is performed on a standing mare and is done transvaginally. It is, therefore, less invasive than a laparotomy (a surgical incision into the abdominal wall or flank) or a laparoscopy (a procedure using an endoscope inserted into an incision in the abdominal wall or flank for the purpose of examination or performing surgery). These two methods are more complex in that they require surgical training and a sterile setting. These procedures also are expensive and require post-operative healing time. Like any surgery, there could be complications.

In the modified technique, 24 or 48 hours after depositing of the microspheres the uterus was washed out with a sterile saline solution (a uterine lavage). The fluid that recovered from the lavage was put into a centrifuge. These samples were tested for the presence of the microspheres.

Of the 13 mares tested, eight showed patency of both uterine tubes at least once, indicating that both were able to transport the microspheres.

What does all of this mean for the mare owner? It means that there is now a procedure that can be done with a minimum of invasion to the mare (a single procedure), done more inexpensively for the owner, and can determine the patency of both right and left uterine tubes.

About the Author

Tom Hall

Tom Hall is a former English professor with a BA from Georgetown College, a JD from the University of Kentucky School of Law, and an MA in English from Western Kentucky University. He is an assistant editor for Eclipse Press.

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