468 FARM ANIMALS 
of insects. In combating this disease medical treatment 
is of little value. Fortunately a vaccine has been discov- 
ered that is very effective as a prevention. 
3. Blackleg.—An infectious disease produced by the 
blackleg bacillus, a parasite that lives and propagates in 
the soil of infected districts and in the bodies of diseased 
animals. The disease is characterized in the appearance 
of large swellings on various parts of the body, usually 
on the upper portions of one of the legs, and never below 
the knees. Swellings vary in size and are always formed 
by the presence of gas formed in the tissue just beneath 
the skin. This gas is a product of the germ. A peculiar 
cracking sound is noticed as the hand is passed over the 
swellings. When punctured, these swellings emit a 
bloody fluid of disagreeable and sickening odor. 
Associated with the disease are loss of appetite, high fever and 
lameness. Death follows shortly after time of attack. No medical 
cure for treatment has been discovered. The only safe practice in 
regions where bDlackleg 
is prevalent is in the use 
of protective inoculation 
or vaccination. Such 
vaccination renders the 
animals immune, and 
even if attacked, there is 
almost no appearance of 
the disease. 
4. Fistule. — A 
chronic discharge 
from some tubelike 
channel, with no 
tendency to heal 
and most common in 
horses. They may 
be located on the withers (fistulous withers), on the side 
of the face (tooth fistula), on the breast bone (sternal 
fistula), or on the lower jaw (salivary fistula). Fistylous 
( 
. FISTULA OF THE WITHERS 
