Progressive ataxia in a captive North American river otter (Lontra canadensis) associated with brain stem spheroid formation.

Progressive ataxia, particularly of the hind limbs, developed in a paretic female juvenile captive North American river otter (Lontra canadensis). Severe bilaterally symmetrical axonal degeneration in the medulla oblongata (nucleus gracilis and nucleus cuneatus) and multiple scattered spheroids in the region of the pons were detected microscopically. This is the first description of ataxia associated with axonal degeneration in otters.