670 
PARALYSIS OF THE HIND LIMB. 
semi-tendinosus, semi-membranosus, and biceps femoris were found to 
remain relaxed and without movement. 
Sensation in the 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 croup, some in the paraproctal connective tissue. Except 
for compression by the abcess, the rectum seemed to have escaped any 
disease change. As the abscess cavity clo.sed, 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 over” 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 nerves 
were affected. The symptoms due to injury of the external popliteal 
were more marked because the function of those supplied by the internal 
popliteal (gastrocnemius, flexor perforans, perforatus, &c.) was partially 
replaced by their tendinous apparatus ; this explains why weight could 
still be borne on the limb. 
Szidon states having seen paralysis of the external popliteal nerve, 
consequent on injury by small shot. 
Goubaux gave an excellent description of paralysis of the external 
popliteal nerve as early as 1848. His case was caused by a violent 
contusion, and was unsuccessfully treated by repeated blistering along 
the course of the nerve. 
Bouley cured one case by similar applications. 
Cadiot has only seen one case. It recovered in three weeks hy 
blistering and exercise. 
(b) Moller has seen and described one case of paralysis of the 
internal popliteal nerve. In this disease the muscles lying at the 
posterior surface of the tibia are affected ; plantar flexion is impossible, 
that is to say, the hock cannot be extended nor the foot flexed (in the 
plantar sense). As, however, in the horse flexion of the hock brings 
both flexors of the foot, and especially the tendon of the flexor pedis 
perforans, into tension, the phalanges are, in this lameness, necessarily 
fixed in a position of plantar flexion. This is especially noticeable when 
