26 CIRCULAR 14 8, U. S. DEPARTMENT OF AGRICULTURE 



doses of phenothiazine as described above, experience has shown that 

 strongyles can be kept at minimum numbers by allowing pastured 

 animals free access to loose mixtures containing about 1 part of pheno- 

 thiazine to approximately 40 parts of granular salt or mineral mixture. 

 It is generally necessary to encourage consumption of the mixture by 

 adding, from time to time, a small amount of grain feed. Animals on 



Figure 17. — Horse suffering from gross infestation with parasites (strongylosis)- 

 Note marked emaciation. Following treatment for the removal of parasites, 

 this horse made a good recovery. 



such a regimen should be given some surveillance in order that thera- 

 peutic treatments may be given, if necessary, to animals which may 

 not consume sufficient amounts of the free-choice mixtures. 



Another drug often used for the removal of large strongyles is oil 

 of chenopodium. It is very effective and usually safe, but horses 

 are sometimes slow to recover from the after effects of the medication. 

 When this drug is used, the animal should be fasted for 24 to 36 

 hours before treatment and the drug should be given in a dose of 

 from 4 to 5 fluid drams (16 to 20 cubic centimeters) for a 1, 000- 

 pound animal, or at a dose rate of 1 fluid dram (4 cubic centimeters) 



