PARALYSIS OF THE HIND LIMB. 



941 



lower parts of the thigh and about the phalanges was also impaired. 

 The animal, however, regularly reacted to stimuli in the region of the 

 quarter and upper thigh. 



Three weeks after the first appearance of lameness an inflammatory 

 swelling appeared between the anus and tuber ischii, showed 

 fluctuation, and on incision discharged about two quarts of very 

 offensive lumpy pus. After enlarging the orifice, the hand could be 

 introduced into an extensive cavity consisting of several divisions, 

 some lying between the muscles of the quarter, some in the paraproctal 



Fig. 523. — Paralysis of the external popliteal nerve. 



connective tissue. Except for compression by the abscess, the rectum 

 seemed to have escaped any disease change. As the abscess cavity 

 closed, the difficulty in movement gradually diminished though the gait 

 for long remained uncertain, especially when the horse was on uneven 

 ground, the phalanges failing to be extended and the animal ' ' knuckling " 

 at the fetlock. At this stage the animal passed from observation. 



There can be no doubt that the abscess originated in the paraproctal 

 connective tissue in consequence of infection from the rectum. It 

 then extended between the muscles of the quarter and pressed on the 

 great sciatic nerve, so that both the external and internal popliteal 



