Seventy-one paraplegic dogs with confirmed intervertebral thoracolumbar disc disease and intact deep pain sensation were treated by hemilaminectomy and fenestration of at least two adjacent discs. The success rate of treatment in the overall population was 86 per cent (61/71 cases), with a mean length of time to regaining the ability to walk of 10·8 days and a mean follow-up time of 29 months. The rate of onset of clinical signs significantly influenced the clinical outcome (P=0·01) but not the length of recovery time (P=0·45). Conversely, the duration of clinical signs did not seem to significantly affect the outcome (P=0·27), but did affect the length of recovery time (P=0·001). Animals which had shown clinical signs for more than six days took significantly longer to regain the ability to walk (ie, an additional 6·9 days, P=0·04 and 4·5 days, P=0·01), when compared with those which had shown clinical signs for less than two days, or more than two but less than six days, respectively.