Technique of Spinal Anesthesia in the Dog.

Abstract

Lumbar puncture of the spinal canal of the dog has been practiced in the Laboratory of Experimental Surgery for the administration of regional anesthesia as well as during the course of other experiments. In the literature, however, it is generally conceded to be virtually impossible to perform successful lumbar puncture upon the dog. 1 We are describing the technique of the method in the hope that it may be of value to others. Out of 45 successive dogs upon which lumbar puncture has been attempted, 37 were successful; the failures were obtained in the earlier attempts when the technique was being elaborated.

The dog has 7 lumbar vertebrae. The spinous processes of these vertebrae in contrast to the human point cephalad. The vertebrae and their processes are closely united in the living animal, especially in the mid-line, and it is virtually impossible to pass a spinal puncture needle between them at this point, except between the last lumbar vertebra and the sacrum. Injection of anesthetics at this point does not ordinarily allow for diffusion to a level sufficiently high to induce true spinal anesthesia, and usually results only in sacral anesthesia. Laterally, however, there is a very definite interspinous aperture between the superior and inferior surfaces of any 2 adjacent lumbar vertebrae. Upon arching the spine of the animal, the aperture attains a diameter of about 2 to 3 mm., is about 2 to 3 mm. deep and connects directly with the dura. The axis of this canal in the sagittal plane is about 10 degrees with the frontal plane in the upper lumbar region, and about 45 degrees in the lower lumbar region. In the frontal plane, the axis of this canal is about 5 decrees with the sagittal plane.