Objective To establish a canine model of intervertebral disc extrusion by surgery and observe the histological and microcirculatory changes of the spinal cord , in order to accumulate data for studies on the pathology and mechanism of treatment for intervertebral disc extrusion .Methods Normal healthy adult dogs were divided randomly into two groups:normal control group and model group .To simulate the intervertebral disc extrusion caused by spinal cord compression, 6Fr double lumen catheter with ballon was inserted into the spinal cord T 12-T13 and filled with about 5 mL Iohexol after the exposure of spinal cord L 1 by hemilaminectomy .The spinal cord blood flow ( SCBF) at the L1 level before and after compression was measured by laser-Doppler flowmetry .Morphological changes of the compressed spinal cord at 14 days after compression was examined by histopathology .Results The ( Texas spinal cord injury score ) ( TSCIS) scores of the motor function of bilateral hind limbs were highly significantly decreased (P<0.01).The blood flow of spinal cord at the L1 level was significantly decreased (P<0.05) after compression than that before .Compared with the normal control group, the model group showed abnormal vacuolization in the white matter and the number of normal neurons in the ventral horn of gray matter was significantly lower ( P<0.01 ) .Conclusions Our findings demonstrate that canine models of intervertebral disc extrusion can be successfully established by balloon catheter compression , showing local impairment of microcirculation and histological changes in the spinal cord .This canine model may provide a useful model for evaluation of therapeutic effects of acupuncture and for mechanism studies .