What Is Your Diagnosis?

Benjamin R. Buchanan Brazos Valley Equine Hospital, 6999 Hwy 6, Navasota, TX 77868.

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 DVM, DACVIM
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Carla S. Sommardahl Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37902.

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 DVM, PhD, DACVIM
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Rebecca R. Moore Department of Pathobiology, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37902.

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Robert L. Donnell Department of Pathobiology, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37902.

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 DVM, PhD, DACVP

History

A 15-year-old Tennessee Walking Horse mare was evaluated for acute clinical signs of colic that had not resolved after IV administration of flunixin meglumine by the referring veterinarian. The horse had intermittent episodes of colic during the preceding 6 months that had resolved with minimal intervention. On physical examination, signs of abdominal pain were not detected. The horse had a heart rate of 48 beats/min (reference range, 36 to 48 beats/min), a capillary refill time of < 2 seconds, and pink mucous membranes; however, spontaneous reflux was detected from both nostrils. Results of abdominocentesis, CBC, serum biochemical analyses, and rectal examination were considered normal. Six liters of fluid (pH < 3) was obtained during nasogastric intubation. Signs of abdominal pain were detected only when the mare was permitted access to food or water. Ultrasonography of the abdomen was performed (Figure 1).

Figure 1—
Figure 1—

Cross-sectional transabdominal ultrasonographic image of the abdomen of a 15-year-old horse evaluated for acute clinical signs of colic. The image was obtained at the 13th intercostal space on the right side by use of a 3.5-MHz curvilinear probe at a maximum depth of 21 cm. Dorsal is to the left.

Citation: Journal of the American Veterinary Medical Association 228, 9; 10.2460/javma.228.9.1339

Determine whether additional imaging studies are required, or make your diagnosis from Figure 1—then turn the page

Diagnostic Imaging Findings and Interpretation

Hypoechoic fluid is evident between the duodenal and pyloric mucosal surfaces (Figure 2). In addition to the duodenal pyloric mucosal interface, a pyloric serosal interface, and a pyloric mucosal luminal mass interface can be seen. The characteristic target sign was detected in the 13th intercostal space at a depth of 10 to 19 cm, and the intussusceptum could be followed caudally to the 14th intercostal space on the right side. In the 15th intercostal space, the duodenum was filled with fluid and slightly dilated with a wall thickness of 6 mm. When the duodenum was followed cranially from the 13th intercostal space, the characteristic target sign was lost, and the duodenum appeared dilated with a solid intraluminal mass surrounded by fluid; this appearance was consistent as far cranially as the duodenum could be detected ultrasonographically. On the basis of the ultrasonographic findings, it was believed that a duodenal-duodenal or pyloric-duodenal intussusception was the most likely cause of the pyloric out-flow obstruction. A duodenal mass was also considered.

Figure 2—
Figure 2—

Same ultrasonographic image as in Figure 1. Notice the characteristic target sign is composed of the following layers: duodenal serosa (d), duodenal pyloric mucosal interface (DM), pyloric serosal interface (p), pyloric mucosa (PM), and the pyloric mass (2). Notice the hypoechoic fluid (1) between the duodenal and pyloric mucosa. These findings are compatible with a pyloric-duo-denal intussusception.

Citation: Journal of the American Veterinary Medical Association 228, 9; 10.2460/javma.228.9.1339

Comments

The duodenum can be located consistently via ultrasonography in the right cranial to middle portion of the abdomen along the caudal and medial margin of the right lobe of the liver and can be followed caudodorsally to the caudal pole of the right kidney where it turns medially along the base of the cecum. When close to the body wall, intussusceptions are easily detected by ultrasonography.1 The characteristic target sign is obtained by imaging through the apex of the intussusception where the intussusceptum is surrounded by fluid and the intussuscipiens.

Gastroscopy performed 12 hours after initial evaluation revealed narrowing of the glandular mucosa at the lesser curvature of the stomach, obscuring any view of the pyloric antrum (Figure 3). The endoscope could not be advanced through the narrowed area, confirming a pyloric-duodenal intussusception. Standing laparoscopic surgery was performed to visualize the duodenum. The mare died during the procedure because of intraoperative complications. Necropsy revealed a polypoid mass (16 × 7 × 3.5 cm) originating from the glandular region of the stomach and protruding through the pyloric antrum, causing a 20-cm intussusception of the pylorus into the proximal portion of the duodenum. Results of histologic examination indicated that the mass was compatible with adenomatous polypoid gastric hyperplasia. A similar type of mass causing a pyloric outflow obstruction, but not an intussusception, has been reported in a horse.2

Figure 3—
Figure 3—

Gastroscopic view of the lesser curvature of the stomach of the horse in Figure 1 obtained with a 3-m video endoscope. The normal pyloric recession is lost as the glandular mucosa is being pulled distally into the lumen by the intussusceptum. The ventral glandular mucosa appears hyperemic and inflamed. No ulcers were detected.

Citation: Journal of the American Veterinary Medical Association 228, 9; 10.2460/javma.228.9.1339

In horses, pyloric outflow obstructions have been detected secondary to gastric squamous cell carcinoma and gastric impactions; however, to the authors' knowledge, this is the first report of pyloric outflow obstruction secondary to pyloric-duodenal intussusception.

  • 1

    Reef VB. Adult abdominal ultrasonography. In: Reef VB, ed. Equine diagnostic ultrasonography. Philadelphia: WB Saunders Co, 1998;273363.

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  • 2

    Morse CC, Richardson DW. Gastric hyperplastic polyp in a horse. J Comp Pathol 1988;99:337342.

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