Using ultrasound to diagnose problems in the horse is not a new concept, but it is not as often used in foals as it is in mares. Rob Franklin, DVM, Diplomate ACVIM, of the Goulburn Valley Equine Hospital in Victoria, Australia, discussed ultrasonography of the neonatal foal at the Western Veterinary Conference, held February 15-19 in Las Vegas, Nev.

"You can do quite a bit more with that probe (that most of you carry around already) than you think," he said. "It's good for imaging structures in the abdomen, umbilicus, and thorax (chest), as well as rectal examination of the mare. The only way to get good at it is to get a good atlas or ultrasound text and go to work!"

His first focus was on imaging the colicky foal's abdomen, noting that several problems can be clearly visualized when scanning from under the belly. He used multiple images and videos to illustrate the characteristic appearance of several problems.

"A strangulating obstruction shows as a hypoechoic (black), thickened intestinal wall, and an intussusception (telescoping in of a part of the intestine on itself) has a characteristic target-like appearance (on the screen)," he said. "Also, an abscess is a distinctive mottled-looking region with areas of blackish gray and white. Its size can vary, and an abscess can be quite big. There might also be several small abscesses in the mesentery (membrane that supports the intestine in the body cavity) with Rhodococcus equi infection."

He also described the diffusely swollen small intestinal wall characteristic of enteritis, adding that the horse's moderate pain level, fever, and abnormal white blood cell count can help diagnose the condition. Hernias were also covered, as was ruptured bladder.

Franklin described normal anatomy and normal sizes of the umbilical artery and vein in the neonatal foal, explaining that arteries can look very different in terms of size and shape and still be normal. He also discussed the problem of an abscessed umbilical vein. "These may represent a surgical dilemma if they don't respond to treatment," he said.

Franklin went on to discuss cellulitis in the umbilical stump (which shows as white areas) and several disorders of the urachus. "Urachal abscesses are very common--this is actually the most common finding a veterinarian will see when ultrasounding the umbilicus," he said.

"This (thorax imagery) is certainly the one you can and should put into practice if you're not using it," Franklin stated. "Just keep in mind that you can only see the surface of the lung. If a lesion is deeper than that, you'll miss it."

He described and showed characteristic lung lesions from R. equi, bronchopneumonia, and pleural abnormalities (of the membrane lining the chest cavity). "Angle the probe to match the angle of the ribs," he said. "The normal lung has a hard white line as its border. With bronchopneumonia lesions, you see these 'searchlight' or 'comet tail' lesions beginning at the lung surface and extending into the lung. A R. equi abscess will have a  hypoechoic cavitary appearance.

"The bottom line is that you've already got the tool, and it can help you do a lot for the foal," Franklin said.

About the Author

Christy M. West

Christy West has a BS in Equine Science from the University of Kentucky, and an MS in Agricultural Journalism from the University of Wisconsin-Madison.

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