DISEASES OF THE NERVOUS SYSTEM. 229 
concussion, or shock, or any disease in which the whole brain struc- 
ture is involved in functional disturbance. 
HEMIPLEGIA (PARALYSIS OF ONE SIDE OR HALF OF THE BODY).—Hemi- 
plegia is frequently the result of a tumor in the lateral ventricles of 
the brain, softening of one hemisphere of the cerebrum, pressure 
from extravasated blood, fracture of the cranium, or it may be due 
to poisons in the blood or to reflex origin. When hemiplegia is 
due to or the result of a prior disease of the brain, especially of an 
inflammatory character, it is seldom complete; it may affect only 
one limb and one side of the head, neck, or muscles along the back, 
and may pass off in a few days after the disappearance of all the 
other evidences of the primary affection. In most cases, however, 
hemiplegia arises from emboli obstructing one or more blood vessels 
of the brain, or the rupture of some vessel the wall of which had 
become weakened by degeneration and the extravasation of blood. 
Sensibility in most cases is not impaired, but in some there is.a 
loss of sensibility as well as of motion. In some cases the bladder 
and rectum are involved in the paralysis. 
Symptoms.—tin hemiplegia the attack may be very sudden, and 
the animal fall, powerless to move one side of the body; one side of 
the lips will be relaxed; the tongue may hang out on one side of the 
mouth; the tail curved around sideways; an inability to swallow 
feed or water may be present, and often the urine dribbles away as 
fast as it collects in the bladder. Sensibility of the affected side may 
be entirely lost or only partial; the limbs may be cold and sometimes 
unnaturally warm. In cases wherein the attack is not so severe the 
animal may be able to maintain the standing position, but will have 
great difficulty in moving the affected side. In such cases the animal 
may recover from the disability. In the more severe, in which there 
is complete loss of power of movement, recoveries are rare. 
PaRaPLEGIA (TRANSVERSE PARALYSIS OF THE HIND EXTREMITIES) .— 
Paralysis of the hind extremities is usually due to some injury or 
inflammation affecting the spinal cord. (See “Spinal meningitis,” 
p. 232, and “ Myelitis,” p. 233.) It may also be due to a reflex irri- 
tation from disease of peripheral nerves, to spinal irritation or 
congestion caused by blood poisons, ete. 
Symptoms.—When due to mechanical injury of the spinal cord, 
from a broken back or spinal hemorrhage, it is generally progressive 
in its character, although it may be sudden. When it is caused by 
agents in the bood, it may be intermittent or recurrent. 
Paraplegia is not difficult to recognize, for it is characterized by a 
weakness and imperfect control of the hind legs and powerless tail. 
The urine usually dribbles away as it-is formed and the manure is 
pushed out, ball by ball, without any voluntary effort, or the passages 
may cease entirely. When paraplegia is complete, large and ill-con- 
