Sheep Scab 167 



other farm animals are effected with the mite causing sheep scab. How- 

 ever, the mite causing scab of cattle is quite similar. Sheep scab is in- 

 troduced into healthy herds by the introduction of scabby sheep or har- 

 boring healthy sheep in stock cars, pens, or barns that have previously 

 been occupied by scabby sheep. Just how long such inclosures or pas- 

 tures will hold the infection seems to vary with the weather conditions. 

 The mite seems to live longer without the sheep in summer. An in- 

 fected barn would probably harbor the disease from April to Septem- 

 ber. In cold weather 30 days would probably be the limit of life of the 

 mite without the sheep. However the scab seems to thrive best on sheep 

 before they are shorn. After shearing, the disease often is not noticea- 

 ble till fall, and then may reappear. 



SYMPTOMS 



The first symptom that attracts the shepherd's attention is itching 

 or rubbing of the sheep against fences, posts, buildings or any object 

 the sheep may come in contact with. 



The back, flank, sides or tail are the first places attacked. The mite 

 does not bother the head, bare legs, chest or abdomen. The rubbing is 

 especially noticeable after the sheep become warm by driving and is 

 more noticeable in the evenings. At this stage of the disease if the wool 

 is parted, a reddish or yellowish nodule the size of a timothy seed may 

 be found on the skin. These spots may be scattered over the regions ef- 

 fected or the one spot may continually grow larger in area till a large 

 per cent of the wool is lost. After the first symptoms appear, (itching 

 and nodular spots) the wool of the area will bulge out further than the 

 wool surrounding and it may become yellowish at first, no larger than 

 a pin head. After the wool is lost the nodules of the skin or scabs may 

 crack open and bleed. The sheep becomes emaciated and weak. Some- 

 times wool is lost from sheep from an unknown cause. Com is supposed 

 to cause loss of wool when excessively fed. Lice or ticks might cause 

 itching, so an exact diagnosis can only be made by finding the mites. 

 They are more numerous at the outer surface of the nodular swelling 

 close to the skin. Pull some of this wool and a portion of a scab, 

 place it on black paper and try to find the mites smaller than the diameter 

 of a pin and 1-50 of an inch long. A hand reading glass will aid the eye 

 in locating the mites. A warm room will induce them to crawl. The 

 finding of these grey mites is not so easy as one would suppose but it 



