144 



FARMER'S CYCLOPEDIA OF LIVE STOCK 



Scab — Taking the country as a whole 

 scab is the most important disease af- 

 fecting sheep. It is due to the pres- 

 ence of a mite (Psoroptes communis 

 ovis) in the skin and is readily 

 contagious from one animal to another. 



Fig. 99 — A SMALL PORTABLE DIPPING VAT 

 FOR SMALL FLOCKS 



The mite burrows in the skin, causing 

 an intense itching and irritation which 

 leads to the formation of pustules, scabs, 

 and the loss of wool. The infected area 

 of the skin rapidly extends as the mites 

 multiply, so that the disease pro- 



stages before scabs have formed and be- 

 fore the wool begins to fall off. Loose 

 locks of wool are soon observed and as 

 the scabby area extends over the shoul- 

 ders, back and sides, the affected sheep 

 presents a very disagreeable appearance. 

 Investigation and results — It has 

 been found that scab mites may live for 

 six months or longer in the soil of infest- 

 ed localities without any nourishment 

 derived from sheep. If the eggs of the 

 mite are kept at a temperature nearer 

 that of the body they hatch within 

 about four to eight days. Sheep scab 

 prevails to the greatest extent over the 

 western range districts, where sheep are 

 kept under less careful supervision than 

 when raised in small flocks on farms in 

 the thickly settled eastern agricultural 

 regions. Too little attention was paid to 

 the gradual spread of this disease un- 

 til it finally became a veritable plague 

 and was forced upon the attention of 

 federal and state sanitary officers and 



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Fig. 100 DIPPING PLANT 



grosses over nearly all parts of the 

 body, which are heavily covered with 

 wool. The irritation makes the sheep 

 restless and causes them to rub and bite 

 affected parts and these actions on the 

 the part of the sheep constitute one of 

 the surest symptoms by which the dis- 

 ease may be recognized in the early 



upon the sheep raisers themselves. The 

 work of eradication was then taken up 

 in a vigorous manner by the Bureau of 

 Animal Industry and by various state 

 veterinarians and other local stock of- 

 ficials and has been carried on for many 

 years with striking results. In 1904, 

 the Bureau of Animal Industry in- 



