Putative congenital bilateral lens anomaly in a free-ranging American black bear cub from North Carolina,USA

Abstract

An ~6-mo-old, free-ranging, male, American black bear (Ursus americanus) cub that was observed stumbling, acting disoriented, and falling, was dispatched and sent for postmortem evaluation. Bilaterally, round concretions were present in both the anterior and posterior aspects of the lens, disrupting the lens epithelium. These concretions were continuous with and extended from the inner surface of the lens capsule, as seen with a periodic acid-Schiff–hematoxylin reaction. Immunohistochemistry for alpha A crystallin was inconsistent, with weakly positive immunolabeling indicative of lens fibers. Other findings in this cub included emaciation and ursicoptic mange. Based on histopathologic findings, in conjunction with the clinical signs observed prior to death, we suspect that the bilateral lens lesions in this cub caused visual impairment. Congenital ocular defects are rarely reported in free-ranging wildlife. Developmental anomalies affecting the lens have not been previously described in Ursidae, to our knowledge.