Question of the Day

An 11-week-old male old English sheepdog is presented with a history of intermittent vomiting and diarrhea since weaning. He drinks and urinates frequently and is undersized compared to his littermates. The owners report pacing, disorientation, and weakness.

Physical exam is unremarkable, but only one testicle has descended. As the puppy explores the room he appears ataxic, stumbles a few times, and presses his head into the wall.

A congenital portosystemic vascular anomaly (PSVA) is suspected.

What laboratory findings would support this diagnosis?