Etiology. Parasites. 705 



vertebral arches (see fig. 100). Tuberculous meningitis is usu- 

 ally seen in the dorso-lumbar portion of the cord, and more 

 rarely in other parts, or even throughout the length of the cord. 

 This leads to the production of a varying number of tuberculous 

 nodules of different sizes with caseous centers. Round about 

 these nodules there are often lesions of a more acute nature. 

 Tuberculosis of the spinal membranes is of very rare occurrence, 

 and so far has been observed in the form of caseous or calcified 

 centers in the lumbar portion of the cord only (George and 

 Johne, Kitt, Steuding, Schmidt, Hamoir). One case has been 

 observed in the dog by Poulin and one in the pig by Vogt. 



In a few cases actinomycosis of the membranes has been 

 observed in cattle (Mathieusen, Koorevaar, Poes). In such 

 cases there was enlargement of the vertebrae with the formation 

 of cavities full of pus. According to Mathieusen the lesions are 

 found in the anterior parts of the neck and back. 



Neoplasms are rarely the cause of compression of the cord. 

 In many cases they develop in the neighborhood of the verte- 

 bra and, penetrating through the intervertebral foramina, or 

 through the vertebrae themselves, gain access to the canal (Dorr- 

 wachter. King, Hertwig, Petit, Hutyra & Marek). In other 

 cases they develop in connection with the bones, the membranes, 

 and, in very exceptional cases, the cord itself. In cases of general 

 melanosis in the horse, and especially in gray horses, melano- 

 mata develop in connection wdth the vertebrae, and m very oc- 

 casional cases, exclusively in the meninges. These growths ap- 

 pear to be found most commonly in the dorso-lumbar region. 

 Sarcomata have been met with in the horse, ox and dog, gho- 

 mata and glio-sarcomata in cattle, (Kitt and Dorrwachter), 

 papillomata and sarcomata occasionally in the horse, lipomata 

 principally in cattle, cholesteatomata in the horse and^ dog 

 (Dexler), and finally, chondromata in horses. From a clinical 

 point of view, inflammatory tissue produced by injuries (hem- 

 orrhages, fissures in bone; Frohner, Rubay and Navez) is as 

 important. Exceptionally aneurism of the aorta causes ero- 

 sion of the bodies of the vertebrae, and compression of the cord 

 (Schmidt). In one case recorded by Jakschatsch, there was 

 cystic dilatation of the canal of the cord at the level of the 

 seventh dorsal vertebrae of a calf showing pronounced symp- 

 toms of paresis. 



Parasites. The Coenurus cerebralis frequently penetrates 

 into the lumbar portion of the cord in sheep and cattle, and 

 exceptionally also in the horse, and develops into cysts between 

 the membranes that are elongated in shape and about the size 

 of a finger (socalled lumbar staggers). Echinococci and Cysti- 

 cerci occasionally occur (in the pig and dog), and Echinococci 

 occasionally develop in the bones themselves (Feuereissen 

 Goldmann and Stroh). According to Hinrichsen, Brauer, and 



