Acquired structural kyphoscoliosis in a captive adult female rhesus macaque (Macaca mulatta)

Abstract

A female, wild-caught, rhesus macaque (Macaca mulatta), in captivity for 23 years and estimated to be older than 26 years, had an 8-year history of progressive spinal curvature. Scoliosis was initially noted 1 year after a therapeutic bilateral ovariectomy to treat endometriosis. Eight years after the initial diagnosis, the curvature had progressed to a structural (nonflexible), lumbar scoliosis with a curvature to the left and a structural thoracolumbar kyphosis. The spinal curvature was characterized radiographically by a severe, major lumbar curve to the left with vertebral rotation and severe thoracolumbar kyphosis. The Cobb method of measurement identified a major left lumbar curve of 80 degrees. When the animal's condition deteriorated, the animal was euthanized, and a necropsy with postmortem radiographic and microscopic examination was performed. Radiographically and grossly, multiple intervertebral disc spaces were narrowed along the entire spine with ventral bridging intervertebral spondylosis of the lumbar spine. Radiographically, vertebral bodies appeared to be less radiodense and multiple features of degenerative disc disease were present. No clinical evidence of concurrent neuromuscular or mesenchymal disease was noted, and development of lesions after bilateral ovariectomy suggested the kyphoscoliosis was secondary to osteopenia that developed as the result of a surgically induced estrogen deficiency.