Neurohistopathological findings of the effects of amprolium on the brain and spinal cord changes in the a animal model: An experimental study

The aim of the study was to evaluate the polioencephalomalacia induced with amprolium in goats: pathologic changes of the central nervous system. Eight apparently healthy goats of 6 to 9 weeks of age were drenched with amprolium (200 mg/kg body weight) till the development of clinical signs. Three goats of the same age group were drenched with tap water only and these served as controls. Amprolium drenched goats were allowed to die after the onset of clinical signs and control goats were euthanised after the death of amprolium fed goats. At the time of development of typical clinical signs of cerebrocortical necrosis (CCN) the goats were killed and necropsied and a complete histopathologic examination was performed. At necropsy of the four goats, large necrotic lesion was found in the cerebral cortex, and tissue thiamine levels decreased significantly, especially in cerebrum and cerebellum. However, the brain as a whole in all experimental animals, exhibited moderate to severe congestion, oedema and numerous small yellowish foci of varying sizes scattered on the surface of the cerebral hemispheres.Microscopic changes in the brain were limited to gray matter structures of cerebral and cerebellar cortex, caudal colliculi of mid brain, thalamus, cerebellum and spinal cord. There was shrinkage of neurons, perivascular and pericellular edema, necrosis of neurons, satellitosis, glial nodule, gliosis, middle laminar necrosis and deep laminar edema. Blood vessel walls were thickened due to hypertrophy and hyperplasia of endothelial and adventitial cells. Swollen and prominent capillary epithelium, satellitosis, presence of ghost cells, gliosis and perivascular cuffing were also observed but only in some of the animals. In the cerebellar cortex, there was degeneration of Purkinje cells. The caudal colliculi of mid brain showed bilateral malacia. To the best of our knowledge, these researchers questioned the hypothesis that the amprolium could be the major factor causing polioencephalomalacia. This is the first documentation of Amprolium-Induced cerebrocortical necrosis on goat in Iran.