PARASITIC DISEASES 163 



mals. A very common source of infestion is the 

 buying of stock hogs from infested herds and 

 allowing them to mix with the herd without de- 

 stroying the lice and eggs that are on them. 

 The thinness of the coat enables the animal to 

 brush off the lice, and they become scattered 

 around the premises and crawl onto other ani- 

 mals whenever the opportunity offers. The tumble- 

 down, dirty hog houses, sheds and old straw stacks 

 that are often used as quarters for hogs, when once 

 infested with lice, become; centers of infection, unless 

 radical steps are taken to destroy the pest. 



Injurious Results. — Whenever a large number 

 of lice are present on a hog, they cause a great 

 amount of irritation, and the animal becomes 

 restless and does not feed as well as common 

 For this reason growth and thriftiness are inter- 

 fered with. Pigs suffer more than older animals. 

 The irritation to the thin parts of the skin is 

 sometimes quite noticeable, and some authors state 

 that the hog louse is one cause of urticaria (rash 

 or heat sores). Howevfer, when such a condition 

 occurs, it is generally caused by the application 

 of a remedy to destroy the lice. 



The unthrifty condition is not as marked in 

 strong, healthy herds as it is in diseased, poorly 

 cared-for ones. The coat becomes thin and 

 rubbed off, and the skin dirty and more or less 

 covered with scales and sores. There is no 

 positive evidence that the hog louse can convey 

 disease-producing germs from one animal to another. 



