PARALYSIS OF THE II IN I) EXTREMITIES. 747 



of the spinal cord or fracture of vertebrae, but more often results 

 from distemper and depends on chronic disease of the brain or spinal 

 cord. Siedamgrotzky found oedema of the cord, Johne yellow points 

 of softening in it ; and acute or chronic myelitis and atrophy of the 

 cord have also been detected. In three dogs and one rabbit Mauri 

 noted paralysis and rolling movements ; red softening of the cere- 

 bellum was discovered on post-mortem. 



Complete and incomplete paraplegia have also been seen in swine. 

 Complete paraplegia is commonest in sucking-pigs on account of 

 the little animals being trodden on by the mother ; in older 

 swine rickets may produce it. Paraplegia has also been seen in 

 birds ; Siedamgrotzky noted it in parrots. Its cause is little- 

 understood. 



Symptoms and course. It is clear that conditions differing o 

 much in their anatomical causation are not likely to agree in their 

 symptoms. Nor do the clinical appearances usually exhibit such 

 well-marked peculiarities as to admit of definite anatomical diagnosis. 

 The nature of these conditions has already been determined to some 

 extent in man, but in animals it still remains obscure. Researches 

 are specially needed in incomplete paralysis ; exact diagnosis of the 

 causative condition in complete paralysis of the hind-quarters is 

 less interesting on account of the animals being killed as incurable, 

 or dying in consequence of decubitus (a complication which can 

 seldom be prevented), though exceptions occur even here, as, for 

 example, in commotio medullae spinalis, and the course of the disease 

 must, therefore, be carefully watched. The sudden appearance of 

 symptoms, however, does not necessarily indicate acute disease ; 

 an army horse which had suddenly shown paralysis of the hind- 

 quarters was found to be suffering from an osteo-sarcoma of the 

 spinal column. 



Complete paralysis of the hind-quarters is distinguished : — 



(1) By inability to stand. The animals lie and are unable to 

 rise without assistance. In exceptional cases, the function of the 

 crural nerves, and therefore the ability to stand, is preserved, though 

 the animal is unable to walk. This may be due to the fact that the 

 lesion of the spinal cord is behind the exit of the nerve referred to 

 (fourth to sixth lumbar vertebrae). The same peculiarity also occurs 

 in fracture of the spinal column in the dorsal region, as has been 

 noted in horses. Dogs sometimes learn to walk on the fore-legs, 

 as related by Nocard ; they lift the hind-quarters into the air by 

 powerfully contracting the longissimus dorsi, &c, after the manner of 

 circus dogs. 



