160 ANIMAL PARASITES IN THE STOMACH 



encysted. They remain in the walls six or seven months 

 undergoing in this time three successive changes. In the 

 early spring the larvae pass back into the bowel lumen 

 and attain full development. Iii midsummer the females 

 lay their eggs. This applies to all oesophagostoma except 

 the CEsophagostomum dentatmn of swine, which is said to 

 mature within the worm nodule in the wall of the intestine. 



Necropsy. — In sheep and cattle there appear along the 

 course of the small intestine, and often of the cecum, nodules 

 which vary in size from a pin-head to a shoe-button or even 

 larger. The nodules vary in color, the smaller being black 

 or gray and the larger grayish-white. On incision they 

 are found to consist of a thick capsule of connective tissue 

 surrounding a greenish colored, cheesy, or even purulent 

 mass. The small nodules will be found to contain the larvae. 



Symptoms. — Sheep and cattle when feeding upon low- 

 lying pastures, especially during the months of August and 

 September, ingest the larvae. It is also possible that they 

 may become infested in stables. As a rule if only a few 

 nodules are present no symptoms of disease are produced. 

 On the other hand if large numbers occtir (as many as 6000 

 have been noted) symptoms of chronic intestinal catarrh, 

 obstinate diarrhea, anemia, emaciation and cachexia are 

 noted. Nodule disease seems most fatal in pregnant ewes 

 fed dry feed during the early spring months. As half of the 

 flock can die in two or three months the disorder assumes 

 economic importance. 



Diagnosis. — A positive diagnosis can be obtained only 

 from a necropsy. An examination of the feces is of no 

 value, since the ova have not yet been found. 



Treatment. — ^Medicinal treatment is not successful. How- 

 ever, feeding highly nutritious food, keeping the sheep in 

 small flocks and less crowding during the winter season, 

 especially among pregnant ewes, are the principal indica- 

 tions to be followed. 



Echinorhynchus Gigas (Thorn-headed Worm). — Echino- 

 rhynchus gigas is a long, round, white worm varying, depend- 

 ing on sex, from 6 to 35 cm. in length, which inhabits the 

 intestines of swine. The head of this parasite is armed with 

 several rows of strong hooks. 



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