706 I'oinpressioii of the Spinal Cord. 



Homo, the liypoderiiia lineata occurs comparatively frequently 

 in the second stage of its development in the epidural fat in 

 cattle (according to Hinrichsen in forty to fifty per cent of 

 slaughtered cattle). Symptoms are produced very rarely be- 

 cause they leave the cord before their development is complete. 



Abscesses have been observed very rarely in the spinal ca- 

 nal (one case, Raoul). The penetration of pus through the 

 intervertebral spaces from abscesses in the immediate neigh- 

 borhood of the vertebrae is observed somewhat more frequently. 

 In some cases, pus enters the canal by extension of suppura- 

 tive processes involving bone as in the case of glanders (Chauv- 

 rat, Decoste, Anbury, Boisse, Stanton, Tapken). 



Pathogenesis. Any of the primary conditions mentioned 

 may lead to a gradual reduction in the size of the vertebral 

 canal, the result being that the cord and nerve roots are sub- 

 jected to pressure. This occurs earliest in the dorsal region 

 where the canal is comparatively small, and latest in the pos- 

 terior half of the lumbar portion. Many processes cause a 

 local edema of the spinal cord owing to obstruction of the 

 blood or lymph circulation. Hard growths lying outside the 

 cord hinder its motility and consequently tend to cause tearing 

 or crushing of the cord and nerve roots. Degeneration of the 

 intervertebral discs, or caries of the bone, are likely to lead to 

 excessive curvature of the spinal column at the diseased part, 

 dislocation, or fracture of individual bones (Lienaux), and thus 

 lead to compression of the cord or nerve roots. Finally, chronic 

 inflammation of the cord is set up by the persistent mechanical 

 irritation. 



According to Jakob degeneration of the intervertebral discs plays a primary 

 part in the paraplegia which frequently occurs in dachshunds, but in some cases a 

 secondary part through excessive flexion of the spine. Paraplegia is caused far 

 more frequently by stretching and tearing of the peripheral nerves, and particularly 

 at their point of exit through the intervertebral foramina. The correctness of this 

 idea, which is not based upon an analysis of the clinical aspect of the disease, is 

 opposed by the fact that the paraplegia involves all the nerves of the hind parts. 

 This usually indicates supranuclear paralysis and is associated with incontinence of 

 urine and feces. 



Anatomical Changes. In addition to the lesions of the 

 spine and memln-anes already mentioned, the cord is reduced to 

 about a third of its normal thickness at the point where the 

 pressure has been applied. The consistence is often reduced, 

 but in rare cases that have been in existence for some time, 

 it may become more dense. The appearance of the surface on 

 cross section is asymmetrical, the shape of the gray cornua and 

 of the inferior fissure being altered. In very exceptional cases 

 there are no visible lesions of the cord, although the animal has 

 shown severe symptoms during life. 



Exhaustive histological examinations were carried out by Dexler in eases in 

 which the compression of the cord was due to enchrondrosis, enostosis, or neoplasms. 

 At the point where pressure had been exerted and for a certain distance on each 



