270 DISEASES OF THE HORSE. 
When varicose veins exist superficially and threaten to produce incon- 
venience, they may be ligated above and below and thus obliterated. 
Sometimes absorption may be induced by constant bandages. 
AIR IN VEINS, OR AIR EMBOLISM. 
It was formerly supposed that the entrance of air into a vein at the 
time of the infliction of a wound. or in blood-letting was extremely 
dangerous and very often produced sudden death by interfering with 
the circulation of the blood through the heart and lungs. Danger 
from air embolism is exceedingly doubtful, unless great quantities 
were forced into a large vein by artificial means. 
PURPURA HEMORRHAGICA. 
Purpura hemorrhagica usually occurs as a sequel to debilitating 
diseases, such as strangles, influenza, etc. It may, however, arise in 
the absence of any previous disease in badly ventilated stables, among 
poorly fed horses, and in animals subject to exhausting work and 
extreme temperatures. The disease is probably due to some as yet 
undiscovered infectious principle. Its gravity does not depend so 
much upon the amount of blood extravasated as it does upon the dis- 
turbance or diminished action of the vaso-motor centers. 
Symptoms.—This disease becomes manifested by the occurrence of 
sudden swellings on various parts of the body, on the head or lips, 
limbs, abdomen, etc. These swellings may be diffused or very mark- 
edly circumscribed, though in the advanced stages they cover large 
areas. They pit on pressure and are but slightly painful to the touch. 
The limbs may swell to a very large size, the nostrils may become 
almost closed, and the head and throat may swell to the point of suf- 
focation. The swellings not infrequently disappear from one portion 
of the body and develop on another, or may recede from the surface 
and invade the intestinal mucous membrane. The mucous lining of 
the nostrils and mouth show more or less dark-red or purple spots. 
There may be a discharge of blood-colored serum from the nostrils; 
the tongue may be swollen so as to prevent eating or closing of the 
jaws. In the most intense cases, within from twenty-four to forty- 
eight hours bloody serum may exude through the skin over the 
swollen parts, and finally large gangrenous sloughs may form. The 
temperature is never very high, the pulse is frequent and com- 
pressible, and becomes feebler as the animal loses strength. A cough 
is usually present. The urine is scanty and high colored, and when 
the intestines are much affected a bloody diarrhea may set in, with 
colicky pains. Some of the internal organs become implicated in the 
disease, the lungs may become edematous, extravasation may occur 
in the intestinal canal, or effusion of serum into the cavity of the 
