Leukoencephalomacia due to ischemic vascular accident in a Tremarctos ornatus (Spectacled bear)

Abstract

Tremactor ornatus (Spectacled bear) are the only ursids natives of South America and are present in many Zoo collections. Neurologic diseases are not common in this species and brain injuries are linked mainly to viral diseases; however ischemic brain events are not commonly reported. The aim of this paper is to describe the clinical, gross, microscopic, and immunolabeling findings of leukoencephalomacia due to an ischemic vascular accident in a Tremactor ornatus. A captive spectacled bear presented left-sided non-ambulatory hemiparesis, and left-sided hemineglect, but without mentation impair. The animal died spontaneously. Gross findings included asymmetric bilateral friable dusky discoloration areas of malacia, sharply defined in the white matter of the forebrain right hemisphere. Lesions were observed in right parietal and temporal cortex, extending to the thalamus, striate body, and medullary body. Histologically, there was a non-hemorrhagic leukoencephalomacia, with accentuated myelin rarefaction and astrocytes proliferation embedded with Gitter cell infiltrate. Moreover, Luxol Fast Blue highlighted extensive severe myelin loss. The diagnosis was established through the clinical history along with extensive ischemic right hemisphere leukoencephalomacia. Immunohistochemistry was primordial to access repair and inflammatory lesions. To the best authors' knowledge, this is the first report of leukoencephalomacia due to ischemic vascular accident in a Tremarctos ornatus.