Microhepatia on radiographs: gastric axis and portosystemic shunt
7-month-old Yorkshire Terrier, small for its age, with episodes of disorientation and head pressing after meals. Postprandial bile acids are markedly increased.
Which abdominal radiographic finding do you expect?
chevron_right Show answer and explanation
A. Cranial displacement of the gastric axis, more upright or tilted cranially, with the stomach close to the diaphragm
Correct. With a small liver the stomach moves towards the diaphragm and its axis becomes upright or tilts cranially. In portosystemic shunts, large kidneys and urate stones (poorly radiopaque) may also be seen.
B. Caudodorsal displacement of the gastric axis and rounded liver margins extending beyond the costal arch
These are the signs of hepatomegaly, the opposite of what is expected in a congenital shunt.
C. Diffuse mineralisation of the hepatic parenchyma
It is not a shunt finding. Hepatic mineralisations are usually focal (choleliths, granulomas, neoplasms, old haematomas).
D. Generalised loss of serosal detail due to ascites, a constant feature of congenital shunts
Ascites is rare in congenital extrahepatic shunts; it is more typical of portal hypertension (chronic liver disease, acquired shunts) or severe hypoalbuminaemia.
lightbulb Key takeaway
On the lateral view, the gastric axis (line from fundus to pylorus) usually lies parallel to the ribs or between them and the perpendicular to the spine. If it tilts cranially, think microhepatia (shunt, cirrhosis); if it moves caudally, hepatomegaly. In older or obese cats, a liver extending beyond the costal arch may be normal.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.