UNITED STATES DEPARTMENT OE AGRICULTURE 



FARMERS' 

 BULLETIN 



Washington, D. C. 



713 



April 17, 1916 



Contribution from the Bureau of Animal Industry, A. D. Melvin, Chief. 



SHEEP SCAB. 



By Maiuon Imes, yelerinai h f}iHi)ccto)-, Zoological Division. 



CONTENTS. 



History and characteristics 



The parasite which causes sheep scab. 



Symptoms of scab 



Contagiousness of scab 



Page. 



Treatment 15 



Dipping sheep 15 



Cleaning and disinfecting premises 27 



Dipping plants 28 



HISTORY AND CHARACTERISTICS. 



Scabies in sheep, commonly known as sheep scab, is one of the 

 oldest known, most contagious, and most injurions diseases affecting 

 sheep. Its history dates back to the earliest ages of civilization. It 

 is a highly contagious skin disease, easily transmitted from one sheep 

 to another, and spreads very rapidly after being introduced into a 

 flock. It is caused by a small animal parasite, commonly known as a 

 " mite," wdiich lives on the skin. Although the disease is not heredi- 

 tary, it is possible for a new-bom lamb to become infected from a 

 diseased mother shortly after birth, and this fact has led some 

 sheep owners to think it is hereditary. Besides common sheep scab 

 there are several other varieties of scab affecting sheep, each caused 

 by a distinct species of mite, but they are of comparatively little im- 

 portance and will not be considered in this bulletin. 



When allowed to spread, sheep scab causes great financial loss to 

 the industry. These losses are caused by (1) a decrease in the 

 quantity of wool produced, (2) loss in weight and general condition 

 from irritation and other effects of the disease which render the ani- 

 mals unthrifty, and (3) the death of large numbers of infected sheep. 



Note. — This bulletin is intended for the information of sheep raisers and live-stock 

 sanitary officers concerned in the prevention, cure, or eradication of sheep scab. It super- 

 sedes Farmers' Bulletin 159. 



25745°— Bull. 713—16 1 



