THE ACTION OF ANTHELMINTICS ON PARASITES LOCATED 

 OUTSIDE OF THE ALIMENTARY CANAL. 



INTRODUCTORY. 



As commonly employed, the remedies known as anthelmintics are 

 usually efficacious preparations. Their action is based on the prem- 

 ises that they are poisons which can be taken into the digestive tract 

 of such animals as man, the horse, dog, or cat, in quantities not large 

 enough to poison the host but sufficient to stupefy or kill verminous 

 parasites with which they come in contact. The parasites are usually 

 in the small intestine (intestinal helminthiasis) and occasionally in 

 the stomach (gastric helminthiasis). In order to avoid dilution of 

 the medicine, and also to give a more effective contact with the para- 

 site, the patient is prepared in advance by fasting to empty the 

 stomach and intestine. Finally a purgative is administered to carry 

 out the dead or stupefied worms. All this is comparatively simple 

 .and in practice effective. 



Though anthelmintics may be used very successfully in treatment 

 for parasites in the stomach and small intestine of certain animals, 

 they are, as a rule, less satisfactory when applied to ruminants. Medi- 

 cines administered to ruminants must first pass the first, second, and 

 third stomachs, some or all of which are usually well filled with food 

 and difficult to empty in any reasonable period of fasting, before 

 reaching the usual location of gastric parasites, the fourth stomach, 

 through which in turn the medicines must pass before they reach 

 the small intestine. In some cases, however, gastric and intestinal 

 helminthiasis in ruminants may be treated successfully. Perroncito 

 (1885) 1 and Stiles (1902), for example, have reported satisfactory 

 results from the use of various remedies for stomach worms of sheep. 

 Certain experiments have indicated that under the right conditions 

 remedies may pass directly through the first stomach and thus arrive 

 more or less promptly in the second and following stomachs and the 

 intestine. Powers (1909), however, has questioned this, and con- 

 siders medicinal treatment for stomach worms in ruminants unsat- 

 isfactory. 



As to the treatment of parasites located in the large intestine, it 

 has been found in actual practice, even in animals with simple 



1 References to literature will be found In bibliography at end of bulletin. 



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