Abstract

A 7-year-old, 467-pound male California sea lion (Zalophus californianus) presented with severe neurological signs caudal to the pelvis. The animal was unable to move its hind flippers and pelvis, the rear flippers were atrophied and abraded, rectal tone and deep pain were absent, and it was mentally depressed and inappetant. Therapy included prednisone and ampicillin. Over a 15 day period the animal showed improved attitude and appetite; however, there was no indication of muscular innervation caudal to the pelvis. To better visualize the spinal cord, a myelogram was performed. While restrained in a chute under general anesthesia, contrast medium was injected into the subarachnoid space at the atlanto-occipital joint. Ventro-dorsal (VD) myelogram showed a complete obstruction of flow at T6–T7 and a stricture at T3–T4. A shortening of the disc space at T3–T4 was also identified, with bony remodeling. The animal was euthanized due to poor prognosis. Necropsy indicated lesions within the spinal cord and the regional intradural spinal nerves. There was marked spongiosis of the T3–T4 cord, with progressively more severe neuronal degeneration caudally. Intradural spinal nerves had diffuse myxomatous change with mild gliosis and perivascular cuffing. Extradural spinal nerves also had myxomatous change at their periphery caudally. An intra- or extradural mass was not found. Disc material from T3–T4 was degenerate. The changes likely developed from a progressive extradural compression of the cord leading to degeneration of white and gray matter, likely due to a ruptured intervertebral disc.

Acknowledgements

The authors would like to thank Dr. Gary Watson of Michigan State University-College of Veterinary Medicine and the Detroit Zoological Institute hospital and keeper staff.

* Presenting author
+ Student presenter

Literature Cited

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