A Closer Look

Ultrasound is the main diagnostic tool for breeders, and for good reason.

Breeding season is nearly upon us and with it comes many trips from your vet, checking to see when your mares are coming into heat, ready to breed and then whether or not they are in foal. And the main tool of the trade for these examinations is an ultrasound machine.

Vets began using ultrasound regularly in the 1980s. A safe, relatively non-invasive technique, it allows for accurate monitoring of a fetus and diagnosis of reproductive problems. Ultrasound machines all work in basically the same way: They emit high frequency sound waves and pick up low-level echoes that are bounced back by the tissues. Typically, these echoes are then translated into a 2D image that is displayed on a monitor in grayscale. High-density areas, such as bone, appear white, and low-density areas, such as fluid, are black.

Using Ultrasound

According to Stewart Brown II, DVM, a reproductive specialist and partner with Hagyard Equine Medical Institute in Lexington, Ky., the biggest change in ultrasound since it came into use has been its size. “The very first machine fit in the back of a Volvo station wagon and the probe was as big as a hot dog.” Today, there are small, handheld devices and the probe can fit in the palm of your hand. (No doubt the mares appreciate the smaller probe!) These probes now also have multiple frequencies so the vet can look at different depths of the mare and have even more diagnostic options.

There are a variety of reproductive reasons why vets use ultrasound. For one, they are able to monitor follicular and luteal changes in the ovaries to pinpoint exactly when a mare will ovulate. This allows the mare owner to more accurately schedule the breeding, whether it is via live cover or artificial insemination. The fewer breedings it takes to get the mare in foal, the more cost effective. It is possible to ultrasound for pregnancy at 10 to 12 days, but this increases the chances for early embryonic death. Waiting until 14 days is advisable, and at this point the vet can also see if twins are present and evaluate fetal viability and heartbeat. When the fetus is 50 to 70 days old, ultrasound can be used to determine the sex.

In later gestation, ultrasounding is done through the mare’s abdomen rather than via rectal palpation. This allows the vet to monitor fetal heart rate, examine the mare’s internal structures and monitor high-risk pregnancies. It allows the vet to safely monitor the mare in an effort to catch a potential problem right away.

Brown confirms that the risk of doing an ultrasound is no more than that of doing regular rectal palpation. It is a very safe technique and relatively non-invasive. Vets have also not found any problems with frequency of ultrasound in fetal health.

Another area in which Brown finds ultrasound beneficial is immediately after breeding. Some mares hold fluid and he is able to use ultrasound to determine delayed uterine clearance, which (if not addressed) can lead to secondary bacterial infections. Normal fluid appears black in the ultrasound, but if a lot of debris or infection are present, there will be various grey shapes in the fluid. If this is seen, the mare can be treated quickly to remove excess fluid and clear up any infection. She then can be re-bred and has a better chance of getting into foal.

Finding a Machine

If you are in the market for an ultrasound machine, there are various websites dedicated to buying and selling all types of new and used farm and veterinary equipment. Two examples are and And yes, you can even find ultrasound machines on eBay. For more technical information, pricing guides and to arrange for a live demonstration, you may choose to contact manufacturers directly.

Here’s a look at some of the ultrasound machines currently available.

Diagnostic Imaging Systems, Inc., is offering a veterinary ultrasound that will include 61 image memory on a digital clip, 256 shades of gray for finer detail, a built-in shade for daylight scanning and an OB calculations package.

Classic Medical Supply markets two different ultrasound machines. The Micro V6 is a battery-powered, lightweight, rechargeable handheld unit with a 6-inch monitor. It has a USB port that allows for connection to a computer, and it can also connect to a video image printer. The Telavet 500TM, a notebook ultrasound, produces high-resolution digital images with precise measuring capabilities. This machine also supports different probes and is able to output data in various formats. The system comes with the Windows operating system and a CD-R/RW drive.

Universal Ultrasound markets several ultrasound machines to work within different needs and budgets. The UMS700 offers hand-held portability; the Sonovet 600 provides quality black and white images at an affordable price and features a waterproof keyboard. Best-known is the Sonovet 2000; an updated version is scheduled to appear in 2008. This unit is designed for the farm and office. Its rugged construction, including a water-resistant carrying case, is made to endure harsh, outdoor conditions.

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