Pre- and postprandial bile acids: portosystemic shunt
8-month-old Yorkshire Terrier, smaller than its littermates, with episodes of disorientation and head pressing one to two hours after meals. Urine contains ammonium biurate crystals.
| Parameter | Result | Reference |
|---|---|---|
| MCV | 56 fL | 60–77 |
| Urea | 9 mg/dL | 20–50 |
| Albumin | 2.4 g/dL | 2.6–4.0 |
| Cholesterol | 105 mg/dL | 130–300 |
| Fasting bile acids | 45 µmol/L | < 10 |
| Postprandial bile acids | 180 µmol/L | < 25 |
What is the most likely diagnosis?
chevron_right Show answer and explanation
A. Portal vein hypoplasia without portal hypertension (microvascular dysplasia)
It also raises bile acids and is common in Yorkshire Terriers, but is usually found in asymptomatic dogs without encephalopathy, microcytosis or biurate crystals. It is diagnosed after ruling out a macroscopic shunt.
B. Congenital extrahepatic portosystemic shunt
Correct. Small breed, stunted growth, postprandial encephalopathy, microcytosis, low urea and cholesterol, biurate crystals and very high bile acids (especially postprandial) are the classic picture. Confirm with Doppler ultrasound or CT angiography.
C. Chronic hepatitis
Chronic hepatitis affects middle-aged adult dogs and usually causes raised ALT. In a puppy with lifelong signs, a congenital vascular anomaly is far more likely.
D. Juvenile hypoglycaemia of toy breeds
It causes neurological signs in toy puppies, but when fasted rather than after meals, and does not explain the microcytosis, biurates or raised bile acids.
lightbulb Key takeaway
Pre- and postprandial bile acids assess hepatobiliary function and portal circulation in non-icteric patients. Signs after meals, microcytosis, low urea and biurates in a young small-breed dog: think portosystemic shunt.
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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.