884 Diseases of Sheep. 



country being that known as the Dermatodedes ovis. It 

 dwells upon the skin, deriving its nouiishment by sucking 

 the fluids of the animal. Its bites cause severe irritation, 

 and a discharge of serous fluid, which dries on the surface 

 into scabs, whence the disease derives its name. 



The notion that the scab ever arises from neglect, cold and 

 wet, starvation, etc., is obsolete, as it would involve the 

 spontaneous generation of the insect, which is absurd. That 

 it is worse under such conditions is natural ; and that it oc- 

 casionally arises without known cause is owing to the in- 

 tensely contagious nature of the complaint, the astonishing 

 fecundity of the insect, and its tenacity of life. A pasture 

 which has been trod by a flock of scabby sheep has been 

 known to give the disease to another flock three years after- 

 ward. 



It is surprising that Col. Randall, in his able works on 

 sheep husbandry, says that the scab is "comparatively little 

 known" in the United States. On the contrary, it is a very 

 common disease in New England, New York, and other 

 sheep-growing centres. 



S3^ptoms. — The first and most prominent symptom is 

 itchiness, which soon gives the animal a ragged appearance, 

 tufts of wool being pulled out, leaving bare patches. If the 

 skin is closely examined at these places, a small, reddish 

 pimple will be noticed, upon the surface of which a small blis- 

 ter or vesicle forms. Close examination may discover the 

 insect in the vicinity. 



Under this irritation the sheep becomes exceedingly rest- 

 less. It rubs itself against trees, fences and rocks, and bites 

 and scratches itself with feet and teeth. The scabs are torn 

 off, sores form and extend, the appetite is lost, the fleece is 

 ruined, and the animal dies, worn out with the increasing 

 torment. 



