44 



CIRCULAR 148, U. S. DEPARTMENT OF AGRICULTURE 



are formed, and the hair over the affected parts stands erect and some 

 of it drops out. In some cases the affected areas of skin become dry 

 and scurfy, and may have a leatherlike appearance (fig. 28.) 



The mechanical injury to the skin resulting from rubbing and biting- 

 causes large scabs to form, which adhere firmly to the underlying 

 tissues. The large scabs often are broken by the movements of the 

 animal, and blood or serum may stain the scabs a reddish yellow. 



As the disease advances the skin becomes more or less bare in irregu- 

 lar-shaped, bald patches, and is greatly thickened and thrown into 

 wrinkles or folds (fig. 29). In severe cases the horse loses flesh 



Figure 29. — A well-developed case of sarcoptic mange. 



rapidly, becomes greatly weakened, and unless property treated 

 may die. 



Contagiousness . — Sarcoptic mange is transmissible from one species 

 of animal to another, and also from animals to man. Ordinarily when 

 one species of animal contracts the contagion from another species the 

 mites live only a limited time on the new host. Sarcoptic mites of the 

 sheep, hog, camel, dog, cat, and rabbit may 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, espe- 

 cialJy 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. 



