PARALYSIS OF THE HIND EXTREMITIES. 745 



other unexplained causes were at work in these cases. Complete 

 paraplegia has been seen in horses after powerful electric shocks 

 produced by lightning. Paraplegia and general severe nervous 

 depression follow shocks by high-tension electric currents (500 

 volts). Cadiot recently published an interesting report on the 

 subject. (See Jour. Comp. Path., and The Veterinarian, March, 

 1903.) 



Paraplegia may also follow changes in the nerves, vessels, or 

 muscles of the hind limbs. As these will afterwards be considered 

 separately it is only necessary here to mention lesions of the lumbo- 

 sacral plexus and thrombosis of the aorta. 



Since olden times every permanent disturbance of function in the 

 hind limbs has been described as incomplete chronic paraplegia. 

 As a rule such disturbances are accompanied by peculiar irregularities 

 in movement and rolling gait, but these symptoms cannot be viewed 

 as characteristic of any one disease ; they may be caused in various 

 ways. Without doubt change in the spinal cord plays a chief part, 

 but unfortunately in paralysis thorough post-mortem examinations 

 have not been made. The difficulty in movement and the course 

 of the disease point to chronic morbid processes in the spinal cord. 

 In horses, there is usually a difficulty in co-ordinating movement 

 termed ataxia, similar to that in tabes dorsalis in man. The separate 

 groups of muscles do not act together ; harmony of function is 

 wanting. 



The conditions, however, to which these symptoms are due 

 cannot be brought about, as Dieckerhoff believes, by over-extension 

 of the fasciae. In Dourine, which is followed by progressive paralysis 

 of the hind-quarters, changes have been found in the spinal cord. 

 Haemorrhagic myelitis with formation of cavities in the spinal cord 

 (syringomyelitis) and degenerative processes were met with at isolated 

 points. In other varieties of paraplegia changes could doubtless 

 be found in the spinal cord, provided examinations were made in 

 advanced stages and by proper methods. Wolff saw the hind-legs 

 trailed in horses in consequence of fracture of the caudal vertebrae ; 

 here the change had clearly extended to the spinal cord from the 

 point of fracture. On the other hand, it must be allowed that 

 incomplete paraplegia is not always the result of primary disease 

 of the cord, nor even of changes produced in it by infection as in 

 influenza or strangles ; it may also follow disease of the vertebrae. 

 In France, paraplegia is generally considered to result from injury 

 to the spinal column in the dorsal or lumbar region, and is described, 

 therefore, as vertebral displacement (entorse dorso-lombaire). Vatel 



