INFECTIOUS DISEASES. 563 
try. Two distinct stages may be noted which vary somewhat from 
those described in textbooks, but probably no more than could be 
expected when differences of climatic conditions and methods of 
handling are taken into consideration. 
The first stage chiefly concerns the sexual organs and therefore 
differs somewhat in the male and female. In the second stage the 
symptoms indicating an affection of the nervous system are more 
prominent and are not dependent upon the sex of the animal. 
Following a variable period of incubation of from 8 days to 2 
months, there is seen in the stallion an irritation and swelling about 
the penis and sheath. In a few days small vesicles or blisters may 
appear on the penis, which later break, discharging a yellowish, 
serous fluid and having irregular, raw ulcers. The ulcers show a 
tendency to heal rapidly, leaving scars which are permanent. There 
may be more or less continuous dripping from the uretha of a yel- 
lowish, serouslike fluid. Stallions may show great excitement when 
brought in the vicinity of mares, but service is often impossible be- 
cause of the fact that a complete erection of the penis does not occur. 
In the mare the first symptoms may be so slight as to be overlooked. 
The disease, being the result of copulation, usually begins with in- 
flammation of the vulva and vagina. There may be a muco-purulent 
discharge, which may be slight or profuse in quantity, agglutinating 
the hairs of the tail. The mare may appear uneasy and urinate 
frequently. Vesicles may appear on the external vulva and mucous 
membrane of the vulva and vagina which later rupture and form 
ulcers. On the dark skin of the external vulva the scars resulting 
from healing of the ulcers are white, more or less circular in outline, 
from one-eighth to half an inch in diameter, and pitlike. This depig- 
mentation of the skin about the external genitals is permanent. 
Urticarial eruptions or plaques which break out over various parts 
of the body are a frequent symptom seen in animals of either sex. 
These are sharply defined and edematous swellings of the skin about 
the size of a half dollar or may be even larger. The usual locations of 
these plaques are the croup, belly, and neck. 
The intensity of the symptoms mentioned which are significant 
of the early stage of the disease may vary to a wide extent and in 
many instances be so mild as to escape the attention of any but the 
most careful observer. They commonly disappear after a brief 
period. The apparent recovery, however, is not permanent, for such 
animals after a period of variable length manifest constitutional or 
nervous symptoms. These may not appear for several months or 
even years. They consist of a general nervous disorder with stagger- 
ing, swaying gait, especially in the hind limbs. The animal generally 
becomes emaciated, the abdomen assuming a tucked-up appearance. 
The first indication of paralysis will be noted in traveling, when the 
