Figure 14-96.

Focal Symmetric Encephalomalacia, Brain, Transverse Section at the Level of the Basal Nuclei and Rostral Thalamus, Sheep.

A, There are bilateral discoloration and malacia (arrows) in a portion of the basal nuclei. These lesions are caused by an enterotoxin produced by Clostridium perfringens type D. B, Early stage. Note the acute neuronal necrosis (red neurons) with perivascular and perineuronal edema. Inflammatory cells (arrows), including neutrophils and macrophages, are beginning to appear in the perivascular space and will migrate to the necrotic neurons and phagocytose the debris. H&E stain. C, Later stage. Microscopically, the walls of arterioles can be hyalinized and endothelial cell nuclei swollen and vesicular (not shown here) with perivascular leakage of proteinaceous fluid. Pericapillary hemorrhage and acute necrosis of neurons and macroglia can occur. With longer survival, as seen here, lesions include destruction of neuropil, accumulation of neutrophils and foamy macrophages, and lymphocytic perivascular cuffing. In this case the inflammatory response is pronounced and would not be considered typical of this disease. H&E stain.

(A courtesy Dr. D. Cho, College of Veterinary Medicine, Louisiana State University; and Noah's Arkive, College of Veterinary Medicine, The University of Georgia. B courtesy Dr. B.E. Walling, College of Veterinary Medicine, University of Illinois. C courtesy Dr. J. Simon, College of Veterinary Medicine, University of Illinois.)