Hydronephrosis in a dairy calf: A diagnosis delayed by a clinician's Bayesian brain reasoning.

A 3-week-old female dairy calf was presented because of severe weakness and diarrhea. Physical examination and ultrasound findings lead to a tentative diagnosis of intestinal obstruction, although serum biochemistry suggested a primary renal disorder. Reassessment of ultrasound images allowed diagnosis of hydronephrosis that had been misdiagnosed probably because of the clinician's biased Bayesian reasoning. Pyelonephritis without renal failure was diagnosed 2.5 months later. The calf was euthanized and the diagnoses were confirmed.