ANIMAL PARASITES IN THE INTESTINES 137 



horse. The emigration of the larvae from the aneurysm, 

 back to the intestine occurs in that they are carried by the 

 arterial blood to the peripheral intestinal arteries. They 

 then form embolic worm nodules in the bowel walls. Later 

 the larvae perforate the mucous membrane, reenter the 

 bowel and attain sexual maturity. 



Sclerostomum Edentatum.— This parasite is found 

 in the large intestine in about one-half of the horses. The 

 eggs are passed out with the feces. The embryos are taken 

 up with the food and water and enter the digestive tract 

 of healthy horses. They pass into the bowel walls and reach 

 the subserosa of the parietal peritoneum, where they produce 

 hemorrhages in the peritoneum. Occasionally in colts they 

 cause anemia. Their presence frequently induces an ad- 

 hesive peritonitis. Rarely the parasite is found free in the 

 abdominal cavity or in the scrotum. From the subserosa 

 the larvae wander between the leaves of the mesentery back 

 to the large intestines, in the wall of which they become 

 encysted. They later enter the lumen of the bowel and attain 

 sexual maturity. 



Sclerostomum Quadridentatum. — Sclerostomum quadri- 

 dentatum is very rare and does not seem to have a pathogenic 

 action. 



Strong xxus Tetracanthus. — This palisade-worm lives 

 in the mature state in the colon where often large numbers 

 appear in colts. They produce a hemorrhage and even 

 necrotic enteritis with colic and bloody diarrhea. In the 

 feces large numbers of very small strongyli are found. 

 Sometimes death results from bowel hemorrhage. The 

 eggs pass out with the feces and from them rod-shaped 

 embryos form which are ingested by horses with the food. 

 In the intestines they bore into the mucous membrane of the 

 colon and cecum and become encysted. There are frequently 

 found as submucous nodules in the middle of which are the 

 larvae surrounded by pus. Finally the larvae penetrate the 

 capsule into the lumen of the bowel where they reach sexual 

 maturity. 



Treatment. — The treatment consists in the use of vermi- 

 fuges as recommended for round-worms. Of late atoxyl 



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