240 IOWA DEPARTMENT OF AGRICULTURE. 



having a digestive apparatus infest tliese materials wliile others take 

 them through the sliin. 



Of the external parasites of hogs, perhaps the one most commonly met 

 with is the hog louse, known as the Haematopinus suis. This is a large 

 louse, the female sometimes attaining the length of a quarter of an inch. 

 They have a long rather narrow head, and the mouth is fitted for sucking. 

 These lice are found mostly behind the ears, about the root of the tail 

 and in the wrinkles of the skin, although when they become numerous 

 they may be seen anywhere along the back. They cause great irritation 

 to the host, because of the fact that they pierce the skin with their mouth 

 parts many tiriies each day in their efforts to secure the blood of the host. 

 The free use of some one of the good dips will destroy these parasites. 



The mite or parasite which causes mange or scabies of hogs is quite 

 frequently met with, and it is of great economic importance, because when 

 a drove of swine becomes affected with mange they are very much reduced 

 in vitality, and the financial loss is soinetimes quite great. The parasite 

 known as sarcoptes scabei is quite small, although it is the largest variety 

 of its species, the female being only about 1-45 of aa inch in length and 

 about 1-70 of an inch in width. It is quite difficult to locate owing to the 

 fact that it burrows into the skin, and it is only by removng the scab, 

 scraping the skin below it clear down to the quick, and then examining 

 the scrapings with a hand lens, that it is possible to determine definitely 

 the presence of the parasite. 



The condition is at first manifested by a violent itching and inflamma- 

 tion of the skin, seemingly first on the head, especially on the ears and 

 around the eyes. It then spreads to the withers, croup and inner surface 

 of the thighs, and later it invades the entire surface of the body. The 

 presence of this parasite in the skin excites the secretion of a morbid 

 fluid-like substance, which, together with the abundant amount of epider- 

 mic cells, from the dry whitish-gray crusts so characteristic of sarcoptic 

 mange. The skin beomes wrinkled, and the bristles are usually shed, 

 and become glued together into small tufts which lie on the skin and fall 

 off after a time. 



Scabies is transmitted from hog to hog either by direct contact, or 

 through the medium of the bedding in which the hogs sleep. The disease 

 travels slowly, but will in time, unless vigorous means of eradication is 

 instituted, spread to the entire herd. Thorough and frequent dipping or, 

 in bad cases, the application of turpentine eight parts and flour of sulphur 

 one part gives good results. 



Of the internal parasites of hogs the trichina spiralis is a very im- 

 portant one, as it is the cause of the disease known as trichinosis, and 

 which disease may be readily transmitted to man through the eating of 

 the flesh from animals affected with the parasite. 



The parasite (trichina spiralis) is, in case of the female, about an 

 eighth of an inch long and quite slender. The male is only about a six- 

 teenth of an inch long. In the adult stage they always live in the in- 

 testines, and it is the larval form which lodges in the muscles, there be- 

 coming encysted and remaining until the flesh is eaten by some other ani- 

 mal. The parasite is always transmitted from one animal to another by 

 ingestion, either of infected flesh or of excremetitious matter, in which 



