Benign focal L5 nerve root enlargement in a dog

An English Springer Spaniel presented with an acute onset, progressive, left pelvic limb lameness. Magnetic resonance imaging (MRI), computed tomography (CT) and intra-operative findings revealed an enlarged L5 left nerve root without additional abnormalities and therefore no underlying cause for the nerve root enlargement could be identified. The dog made a quick recovery following hemilaminectomy and was clinically normal 45 months after surgery. Morphometric analysis was obtained by measuring sagittal intervertebral foramen (IVF) surface areas. IVF areas in the clinical case were similar to unpublished data in normal English Springer Spaniels. Although a diagnosis of primary IVF stenosis could not be confirmed morphometrically, the lack of additional anatomical abnormalities in combination with an excellent clinical outcome was supportive of this condition. Nerve root enlargement can be caused by benign or malignant conditions.