Inutero infection with which virus can cause cerebellar hypoplasia in calves?

• A. Postnatal Infection with BVD Virus
• B. In Utero Infection with BVD Virus
• C. Bluetongue Virus Infection
• D. BVD Vaccine Reaction

Answer: (B)

Viral infection during pregnancy can disrupt the development of the fetal brain, and the timing of that infection is crucial. Bovine viral diarrhea virus acting in utero during the period when the cerebellum is forming interrupts normal cerebellar development, leading to cerebellar hypoplasia at birth. The resulting calves often show ataxia, tremors, and a wide-based stance due to impaired cerebellar function.

If infection occurs after birth, the cerebellum isn’t still forming, so cerebellar hypoplasia doesn’t develop. A vaccine reaction is not the typical cause of this congenital defect. While Bluetongue can cause fetal abnormalities if the dam is infected during pregnancy, the classic or most repeatedly tested cause of cerebellar hypoplasia in calves is in utero infection with BVD virus.