This case report describes the occurrence of clinically significant osteochondrosis of the seventh lumbarvertebra in a 10-year-old, female Beagle with progressive monoparesis, lumbosacral pain and urinaryincontinence.A presumptive diagnosis was made using radiography and computed tomography. The dog wassurgically treated by a dorsal laminectomy and the detached bone fragment was removed. A postoperativecomputed tomography scan demonstrated the complete removal of the osteochondrotic tissue. Although thedog recovered remarkably after surgery, she developed a clinical relapse after several weeks. The ownersdeclined further diagnostic tests and the dog was euthanized. Histopathological examination of the removedtissue was in agreement with a diagnosis of osteochondrosis of the seventh lumbar vertebra.