120 SWINE PRACTICE 



is parasitic in its larval stage. Its life cycle lias not been entirely 

 worked out, but the ova are discharged from the animal body in 

 the feces and hatch, if climatic conditions are favorable, into em- 

 bryos. Later changes are unknown, but the larvae are ingested 

 with food or drink and bore into the submucosa of the large intes- 

 tine, where they remain from six to seven months and produce small 

 nodules in which they undergo various metamorphoses, finally be- 

 coming sexually mature. They then leave the submucosa nodules 

 and migrate into the lumen of the intestine, where copulation occurs 

 and the female later ovulates in the same location. 



Lesions. — The principal lesion is the submucous nodule that occurs 

 in the large intestine. There may be only a few nodules, or there 

 may be many. These nodules are inflammatory, caused by the pres- 

 ence of the larvae. They are definitely circumscribed with a fibrous 

 capsule; the content of which is inflammatory exudate that later 

 becomes purulent, then caseous, and may ultimately calcify. The 

 nodules first cause a slight, hard, spherical elevation of the mucous 

 membrane about the size of millet seed, but they may later become 

 as large as a pea. In the later stages they assume a greenish-gray 

 cast due to the accumulation in them of pus. The nodules frequently 

 produce erosions and ulceration of the intestinal mucosa, and they 

 may persist and appear as caseated incapsulated masses. The adult 

 parasites may be found free in the large intestine. They are about 

 three-fourths of an inch in length. 



Symptoms. — The extent of invasion sufficient to produce visible 

 symptoms has not been determined, but it is not uncommon to find 

 a few nodules in the intestine of swine that were slaughtered in 

 packing houses and were known to have been previously healthy. 

 The usual symptoms consist of a profuse and persistent diarrhea, 

 emaciation, weakness, and death in the intensely infested animals. 

 The disease is essentially chronic. The course is from two to three 

 months. 



Treatment. — Because of the location of the offending larvae, medi- 

 cation is of no avail. A small percentage of the animals may be 

 saved by dieting and treating the symptoms as they arise. Preven- 

 tion of further spread of the disease should be the chief consideration. 



Trichocephahis Crenatus 

 This parasite is not of common occurrence in America. The worm? 

 are in shape similar to the old-fashioned blacksnake whip, the head 



