Spinal cord compression caused by osteocartilaginous exostoses of the spine in two dogs

Two dogs, one 4 months old and the other 1 year old, had histories of progressive posterior weakness. In both cases, there was severe asymmetric proprioceptive loss but appreciable preservation of strength. Benign, cystic expansile lesions involving the facets and lamina of the thoracic spine were observed radiographically; a single lesioons was demonstrated in the other. Examination of biopsy speciments taken at the time of laminectomy revealed the lesions to be osteocartilaginous exostoses (osteochondromas, ecchondromas, exostoses). The progress of dogs 1 and 2 has been monitored for 1 1/2 years and 9 months, respectively. Dog 1 has no weakness or proprioceptive loss; dog 2 has a mild proprioceptive loss in the right hindlimb.

Myelographic localization of spinal cord compression in dogs. A comparison between cisternal and lumbar injections of metrizamide "Amipaque" in diagnosing and locating spinal cord compression

Metrizamide is a new water-soluble contrast medium possessing unique properties, one of which is that even in an isotonic solution it has a radiographic density sufficient for a diagnostic myelogram. Whereas in the past myelography with water-soluble preparations invariably entailed lumbar injections, which are technically difficult in dogs, the fact that isotonic metrizamide causes so little tissue irritation has made it possible to inject the contrast solution into the cisterna magna. The author has compared metrizamide myelograms obtained with both cisternal and lumbar injections. Myelography with a cisternal injection is preferable for demonstrating cervical cord compressions and also in cases in which it is desirable to obtain myelographic information on both the cervical and the thoraco-lumbar areas. If, on the other hand, it is necessary to determine exactly the extent of a thoraco-lumbar compression before decompressive laminectomy, the contrast should be injected in the lumbar region in such an amount and at a pressure high enough to ensure that the contrast is forced past the site of the compression. The safety of metrizamide will probably enable a better prognosis following surgery than was previously possible.

Some aspects of the pathology and pathogenesis of the myelopathy caused by disc protrusions in the dog

The pathological changes in 23 cord lesions caused by disc protrusion are described. It is suggested that three broad classifications of damage can be found: (1) compressive change; (2) malacia; and (3) diffuse demyelination. The distribution of damage, within the segment, was different in each type of change as were the glial and vascular reactions. It is suggested that vascular factors play a major part in the pathology of the malacic and demyelinating lesions and may be of secondary importance in compressive lesions.

Morphological changes caused by pressure on the spinal cord

The morphological changes in the spinal cord caused by pressure are described in a series of domestic animals of various species. Three types of lesion are distinguished: totally malacic, partially malacic, and non-malacic. In the non-malacic lesion changes are predominantly in the white matter and consist of de-myclination and hyalinisation of small vessels. The possibility that the immediate cause of such non-malacic lesions may be obstruction of venous drainage from the spinal cord is discussed.