Portosystemic shunts are anomalous connections that allow blood absorbed from the digestive tract to skip the liver entirely, so that ammonia and other neurotoxins that would normally be detoxified reach the brain unfiltered. The condition has been documented in cats, dogs, pigs, camelids, horses, cattle and goats, and in young livestock it typically shows up around weaning, when the shift from a milk-based diet to a higher-protein diet increases ammonia production in the rumen and the metabolic burden placed on the liver. Affected animals may fail to thrive, grow poorly, or develop diarrhea, vomiting and neurologic signs such as ataxia, circling, head pressing, seizures and cortical blindness. In livestock, an antemortem diagnosis is often presumptive, built from signalment, history, clinical signs and clinicopathologic findings such as hyperammonemia alongside normal or only mildly elevated liver enzymes.

The five kids in the report came from a single herd in east-central Alabama and were presented to Auburn University’s Large Animal Teaching Hospital between March 2023 and April 2025, at ages ranging from seven to twelve weeks. The first case, a twelve-week-old doeling, was seen on an emergency basis for abnormal behavior, staggering and the development of blindness. The second, a seven-week-old buckling presented in April 2025, showed ataxia and head pressing. After that kid was euthanized following a diagnosis of a portosystemic shunt, three additional kids from the same embryo flush, sharing the same sire and dam but carried by different recipient dams, were brought in for screening even though they showed no clinical signs.

Each diagnostic modality played a distinct role. Transabdominal ultrasonography, performed on the two neurologic kids by a board-certified radiologist using a portable machine with a 3 to 5 MHz transducer, included a complete abdominal examination with color flow Doppler assessment of the portal vein and caudal vena cava. Despite the examinations being considered diagnostic, no structural abnormalities were seen in either kid: the liver appeared normal in size and echogenicity, no intra- or extrahepatic shunts were identified, and portal flow and the caudal vena cava looked normal on both standard and Doppler imaging. Part of the liver could not be evaluated because of overlying lung. The authors attribute this failure to detect the shunts to the anatomy of the goat, in which the rumen obstructs the left side and lung superimposition hampers tracking of the vessels around the sixth and seventh intercostal spaces; in their experience ultrasound has high specificity but poor sensitivity for this condition in goats.

The centerpiece of the report is trans-splenic nuclear scintigraphy, performed in four of the five kids. After sedation with xylazine and midazolam, each kid was positioned in right lateral recumbency over the detector head of a gamma camera. Under ultrasound guidance, 105 MBq of sodium Tc-99m pertechnetate was injected into the splenic parenchyma, and a dynamic acquisition at four frames per second for four minutes captured the transit of the radionuclide bolus. In a normal animal, the bolus travels from the spleen through the portal system into the liver before reaching the heart; in a shunted animal it heads straight for the heart. Regions of interest drawn over the heart and liver allowed the team to calculate a shunt fraction, the percentage of counts reaching the heart relative to the combined heart and liver counts over seven seconds.

The results were striking. In the first kid, the bolus traveled immediately from the spleen through the splenic and portal veins into the caudal vena cava and then the heart, bypassing the liver entirely, with a calculated shunt fraction of 91.7 percent. In the three screened siblings, radioactivity entered the liver and circulated within it before appearing in the heart, with shunt fractions of 2.8, 2.3 and 6.6 percent, and no evidence of a macroscopic shunt. The second neurologic kid did not undergo scintigraphy at all.

Computed tomographic angiography provided the definitive anatomic characterization in the two affected kids. Using a 128-slice helical scanner with a two-phase contrast protocol at 814 mg iodine per kilogram body weight, the team found in the first kid an abnormal branch of the portal vein traveling dorsally and axially to join a hepatic vein branch near its termination in the caudal vena cava, confirming an intrahepatic portosystemic shunt. In the second kid, CTA revealed a large anomalous vessel arising from the left portal branch division and entering the left aspect of the caudal vena cava near the left hepatic vein branch, consistent with a left divisional intrahepatic shunt. Ultrasound had detected none of this.

Clinicopathologic data supported the imaging in the two sick kids. Both had hyperammonemia, with values of 1,284 and 378 micrograms per deciliter against a reference range of 0 to 60, along with leukocytosis with neutrophilia, hypoalbuminemia and, in the first kid, markedly elevated AST and creatinine kinase and mild hyperbilirubinemia. Cerebrospinal fluid from the first kid was blood-contaminated and non-diagnostic, though the cell count remained within normal limits. Necropsy of that kid found no grossly visible shunt, but liver histopathology showed lobular hyperplasia, arteriolar hyperplasia, portal vein hypoplasia, biliary hyperplasia and hepatocyte degeneration, and the brain showed mild multifocal Alzheimer type II astrocytosis, findings the authors describe as consistent with a portosystemic shunt and hepatic encephalopathy.

The authors are careful about what the series does and does not show. With only four animals undergoing scintigraphy and just one shunt-positive case among them, this is a description of technique rather than a validation study; the screened siblings were not confirmed shunt-free by CT, and blood ammonia was not measured in them, which the authors list as a limitation. They note that portal scintigraphy is regarded as a quick, non-invasive, sensitive and specific method in other species, that per-rectal administration is unsuitable in goats because the caudal rectal vein drains into the systemic circulation and can produce false positives, and that scintigraphy may be more financially accessible than CTA where the specialized equipment is available. They also stress a food-safety point: animals given sodium Tc-99m pertechnetate must never enter the food chain, since the radionuclide has a six-hour radioactive half-life but tissue residue of up to 17 days, and no ruminant reproductive-safety studies exist. Larger studies with both normal and affected animals will be needed to establish the test’s true sensitivity and specificity in goats.

What makes the report notable is less the individual diagnoses than the shift it reflects. As goats and other livestock increasingly live as pets, their owners are seeking a level of veterinary care and diagnostic imaging once considered impractical for food and fiber animals. The Auburn team showed that a scintigraphic protocol well established in small animals can be executed in goat kids, that it correctly flagged the one shunted animal among four scanned, and that CTA can then pin down the shunt’s anatomy. For owners of valuable pet livestock facing an animal with unexplained neurologic disease, the work suggests a practical diagnostic pathway, while making clear that in goats, ultrasound alone may not be enough to rule a shunt out.

Subject of Research: Diagnostic imaging, including trans-splenic nuclear scintigraphy and CT angiography, for detecting congenital portosystemic shunts in five Boer goat kids

Article Title: Case Report: Diagnostic imaging for evaluation of five goats suspected to have congenital macroscopic portosystemic shunts

Article References: Schwartz, D. W., Saucedo-Gonzalez, M., Cole, R., Berry, C., Huertas, O., Prim, J. G., Benson, B. C., Waters, K., & Stockler, J. W. (2026). Case Report: Diagnostic imaging for evaluation of five goats suspected to have congenital macroscopic portosystemic shunts. Frontiers in Veterinary Science, 13, 1971772. https://doi.org/10.3389/fvets.2026.1971772

Image Credits: AI Generated

DOI: 10.3389/fvets.2026.1971772

Keywords: goat, portosystemic shunt, nuclear scintigraphy, computed tomography angiography, veterinary imaging, hyperammonemia, hepatic encephalopathy, Boer kids, ultrasonography, pet livestock, case series, Tc-99m pertechnetate