[Chylothorax in a calf]

A case of chylothorax caused by fracture of thoracal vertebrae in a two-day-old Swiss Braunvieh male calf ist described. The clinical symptoms were those of a unilateral, progressive pleural effusion. This was confirmed by radiological and ultrasonographic examinations. Thoracocentesis was performed under ultrasonographic assistance. The liquid obtained from the pleural cavity was turbid and contained chylomicrons, lymphocytes and neutrophilic granulocytes as well as a high concentration of triglycerides. These qualities go together with chylus. Immunohistological examination for BVD virus turned out to be positive. An intrauterine disturbance of osteogenesis due to BVD virus must be considered a possible cause for fracture of vertebrae during delivery.