CRURAL PARALYSIS. 943 



Though post-mortem examination sometimes shows the rectus 

 and vasti muscles in a marked state of fatty degeneration after 

 this disease, that fact in no way proves the condition to have 

 been myopathic lameness, as has been suggested. 



Symptoms. In consequence of loss of power in the sartorius and 

 extensor muscles of the stifle, weight cannot be supported by the 

 paralysed limb, which, at rest, appears drooped at the quarter, flexed 

 at the stifle and hock, with the foot, carried a little forward, resting 

 on the toe. In movement, attempts to sustain the body on the 

 affected limb are at once followed by flexion of all the joints, including 

 the phalanges. The weakness of the stifle is very marked. The skin 

 on the inner surface of the thigh loses its sensibility, and later and 

 gradually the patellar muscles undergo atrophy, while the adductors 

 of the thigh become hypertrophied. 



In incomplete crural paralysis the body sinks towards the affected 

 side, whilst all the joints become somewhat flexed (Fig. 524), the last 

 period of the stride being consequently shortened. Animals suffering 

 from this disease learn to move better, however, in time, the ab- and 

 ad- ductors of the limb co-operating to fix the stifle-joint. This action 

 is easily detected when the animal is walked very slowly past the 

 observer : it is then seen that the upper end of the tibia is not only 

 drawn backwards and upwards, but the patella is fixed on the 

 condyles of the femur. The last symptom to disappear in convalescence 

 is the upright position of the os suffraginis, a consequence of incom- 

 plete action of the rectus and vasti. 



Paralysis of the crural nerve or of the above muscles may be mistaken 

 both for muscular rupture and for lateral luxation of the patella (vide loc. 

 cit.). Ruptures in the various extensors of the i>atella have been seen by 

 numbers of practitioners. Delwart saw three cases of rupture of the rectus 

 femoris in the horse, all caused by slipping or falling ; two proved incurable. 

 The symptoms resembled those of the above-described paralysis. Not 

 infrequently a depression could be detected in the muscle. Post-mortem 

 examination showed the muscles to be pale, as though boiled, their fasciculi 

 shredded out and partly separated. 



Schmidt describes rupture of the vastus externus. A horse had trodden 

 in a deep rut, and, the ground being frozen, was unable to withdraw its foot 

 without assistance. Severe lameness was immediately apparent, the limb 

 was relaxed, and collapsed at every attempt to sustain weight on it ; the 

 stifle and hock were markedly flexed. At first no change could be detected 

 in the muscles, but after some days a depression, about 4 inches deep, 

 became visible on the outer side of the muscles attached to the patella. 

 The horse was unable to rise for fourteen days, but in three weeks' time 

 could again place weight on the limb. In two months it was put to light 

 work, and in three months had entirely regained its usefulness. During 

 its course this case also showed some resemblance to crural paralysis, and 

 it is possible that it may have been of that character. 



