[A case of a congenital high-grade hydrocephalus internus and Dandy-Walker syndrome in a black and white German Holstein calf].

A black and white female German Holstein calf showed a highly deformed cranium. The animal was not able to stand. Further findings were bilateral strabismus divergens and negative pupillary light reflexes. Magnetic resonance imaging and pathological-anatomical examination showed that the cerebrum was replaced to a high degree by the ventricle system filled with 1.5 liters of cerebrospinal fluid. The hemispheres of the cerebellum were ruptured by the dilated fourth ventricle. In addition, the vermis and pons were missing and fluid accumulation in the subarachnoidal space extending up to the first spinal cord segments was visible. Inbreeding was not detected in the 3-generation-pedigree. No other affected calves from the same parents were known at the farm. Chromosomal abnormalities could not be detected after examination of 30 metaphase spreads using a light microscope. Infections and parasitic diseases could be ruled out for this anomaly. Very rare defect alleles might have been involved in the development of these inborn defects.