ANIMAL PARASITES 259 



animals should be dosed daily until tiicv have received from live 

 to ten doses, depeudiu*;- on the condition of the animal. 



Intestinal Worms of Sheep. — The most widely distributed 

 and seemingly most injurious intestinal worm of sheep is the 

 CEsophagodomum cohimhianum. It is a small worm from 0.5 

 to 0.75 inch (12 to IS mm.) long. It penetrates the lining mem- 

 brane of the intestines and encysts in the intestinal wall. A 

 tumor, varying in size from that of a millet seed to a hazelnut, 

 then forms in the wall of the intestine. These tumors undergo 

 a cheesy degeneration, and when mature, may appear as gTeenish, 

 cheesy-like masses, covering a large portion of the lining mem- 

 brane of the intestine. Diarrhoea and emaciation may result. 

 These symptoms are most evident during the winter months. 



The treatment recommended for ridding sheep of this in- 

 testinal worm is largely preventive. Very little can be done 

 with the medicinal treatment of a sheep whose intestinal tract is 

 badly infested with this parasite. Good care and the feeding 

 of a proper ration are the only curative measures that are effec- 

 tive in such cases. The occasional administration of a vermi- 

 fuge for the purpose of ridding the digestive tract of worms, 

 together with the frequent changing of pastures during the 

 spring and summer, are the most effective preventive lines of 

 treatment. The same treatment recommended for stomach 

 worms may be used for this disease. 



Intestinal Parasites of Hogs. — The Ascaris suis or common 

 round worm is very commonly found in the small intestine. It 

 is quite frequently found in large numbers, almost filling the 

 lumen of the intestine of an unthrifty pig (Fig. 75). It may 

 also work its way into the bile duct. Sometimes, after a hog has 

 died, this parasite migrates forward into the stomach and gullet. 

 The A. suis is from 4 to 10 inches (10 to 26 cm.) long. 



The Echinorhynchus gigas or thorn-headed womi is the 

 most dangerous of all intestinal worms (Fig. 7-i). It is usually 

 found with its proboscis or thorn imbedded in the wall of the 



