68 CLINICAL VETERINARY MEDICINE AND SURGERY. 



monest cause of this paralysis. Bruises about the shoulder or arm, 

 kicks, blows from the carriage pole, collisions against the jambs of 

 doors, slips, and falls may all produce it. Prolonged compression 

 resulting from the animal lying in an awkward or enforced position is, 

 however, much the most frequent cause. Radial paralysis is often a 

 sequence of casting, when the horse has been kept down for a long 

 time with its legs crossed, or in the ordinary position, and especially 

 when, under such circumstances, it has struggled violently. As a rule, 

 though not always, the lower limb is that affected. Notwithstanding 

 the assertion of Goubaux, and several other authors, the upper limb 

 may be the seat of injury. I myself have seen one case. In operating 

 on a fore-limb, either the diseased limb itself or that of the opposite 

 side, which before casting was perfectly normal, may become affected. 



Several cases of radial paralysis occurring during work, or in the 

 stable, and quite apart from mechanical injury, have been recorded. 

 The radial may certainly become paralysed in consequence of excessive 

 contraction of the muscles which it supplies, but in cases of this kind 

 either the nerve itself is injured, the paralysis is due to inflammation of 

 muscle, or to polymyositis (inflammation of several muscles) conse- 

 quent on excessive work. 



Paralysis may occur in the stable either in consequence of slipping, 

 of a struggle when rising, or of some peculiar position in which the 

 animal is accustomed to lie. Rheumatic paralysis, or paral3'sis a 

 frigore, and that of infectious or toxic origin, are rare. 



The co-existence of radial paralysis and fracture of the first rib — a 

 fracture which may result from falls or slips — has been demonstrated in 

 many post-mortems. Hunting, relying on several cases in which 

 fracture of the first rib had been detected, expressed the opinion that 

 radial paralysis was probably always a consequence of such injury. 

 This conjecture, however, is disproved by a study of the pathological 

 anatomy of the condition. In most cases post-mortem examination of 

 animals suffering from the disease fails to demonstrate the existence of 

 fracture of the rib. The converse, however, is true, viz. that fracture 

 of the upper part of the first rib is usually accompanied by radial 

 paralysis — a result due to the proximity of the radial nerve to the point 

 of fracture. 



Radial Paralysis generally produces sufficient functional disturbance 

 to permit of diagnosis, but the clinical picture is far from clearly defined. 

 Sometimes the symptoms are very acute and alarming, leading both 

 skilled and unskilled persons to suspect some extremely grave condition 

 like fracture, as in the case we have just seen ; sometimes they are 

 obscure, their significance only becoming clear on careful examination. 



