PARASITES AND PARASITIC DISEASES OF HORSES 4] 
live on horses, and those of the horse, dog, and hog are known to 
be readily transmissible to man. 
Sarcoptic mange of horses is contagious to all classes of horses 
and is usually transmitted by direct contact. with infested animals. 
It may, however, be transmitted by other objects, such as currycombs, 
blankets, or harness, or in stables or other premises. It is important 
that mangy horses be isolated and all equipment kept separate until 
the disease is eradicated. 
Apparently the disease spreads slowly during warm weather, 
especially among horses on pasture, but it makes rapid headway in 
horses closely confined or crowded together in small inclosures. 
Exposure to cold, inclement weather, insufficient feed, or feed of poor 
quality, or any other circumstances ‘tending to lessen the vitality or 
functional activities of horses hastens the spread and development of 
mange. When the mites are active under favorable conditions the 
FIGURE 29.—A well-advanced case of sarcoptic mange 
lesions extend rapidly, and the entire body surface may become 
involved in about six weeks. 
Although they do not propagate themselves except on the bodies 
of animals, the mites as well as their eggs may retain their vitality 
for a considerable time off the host animal. When exposed to sun- 
hght in dry places the sarcoptic mites live only a few days, but 
in moist, protected places they may live three weeks or even longer. 
Although it is difficult to infect horses experimentally from infested 
premises, the possibility that the disease may be contracted from 
such sources should not be overlooked. It is good sanitary practice 
to clean and disinfect all stables and small inclosures which have 
been occupied by mangy horses, also all currycombs, brushes, blan- 
kets, and other objects used on such horses, before using them 
for clean animals. Cleaning and disinfecting for sarcoptic mange 
may be done in the same manner as for lice. 
Treatment—On account of their burrowing habits, sarcoptic 
mites are difficult to eradicate. The common dips, such as lime- 
