Computed tomography (CT) scan findings in calves with hydranencephaly

Background: Hydranencephaly is the unilateral or bilateral loss of cerebral hemispheres and their replacement by a cerebrospinal fluid-filled sac that is caused by some teratogenic viruses. This disorder can be recognized before death occurs, using computed tomography (CT) scan. Pathological findings are also useful for the confirmation of the diagnosis. Aims: The aim of this study was to determine features of hydranencephaly in calves by CT. Methods: In this study, CT images were obtained from the skulls of 7 sameage calves with neurological signs, affected by Akabane virus, after slaughter. To compare the Hounsfield unit (HU) obtained from each brain region with the normal one, a normal calf's (with the same age) CT images were considered. Then, HU was measured in different parts of the affected calves' brain and compared with the normal calf's brain. Results: Computed tomography images of affected calves indicated a hypoattenuated density of cerebral hemispheres, and the mean value of HU significantly decreased in these parts of the brain compared to normal calves (P=0.0001). There was no statistically significant difference between the mean value of the brain stem HU of the affected calves and the normal ones (P=0.066). In the gross pathology, asymmetric fluid-filled sacs that replaced cerebral hemispheres were observed, but the brain stems were intact in all cases. Conclusion: The results showed a strong correlation between CT scan and pathology findings in calves with hydranencephaly. This is the first CT scan-mediated study of calves with hydranencephaly.