14 CIRCULAR 148, U. S. DEPARTMENT OF AGRICULTURE 
worms were present in the lungs and in the windpipe and its 
branches. It is probable that similar symptoms are present in heavy 
ascarid infestations which are acquired naturally in stables and on 
pastures. Ordinarily, ascarid infestations in foals result in un- 
thrifty animals with rough, staring coats, and the removal of the 
worms frequently leads to marked improvement in condition, hair 
coat, and gain in weight. 
Thus it is evident that the ascarid, both as an adult and as a 
wandering larva, has the capacity for causing great damage, and 
that its presence in horses, especially foals, is a possible source of 
2 
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O17? PAUSTUES: S 
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Ficurn 7.—Life cycle of the horse ascarid, Ascaris equorum. The eggs shown in 
this illustration are enlarged about 50 times 
danger. Heavy infestations, in which hundreds of worms may be 
present, may cause illness and even death as a result of the horse’s 
absorption of toxic products produced by the worms. 
Treatment.—Carbon disulphide is an effective remedy for the re- 
moval of ascarids from the horse. The drug is given as follows: 
Fast the animal for 18 hours and give carbon disulphide in a dose 
of 6 fluid drams (24 cubic centimeters) for a 1,000-pound animal or 
at a dose rate of 1.5 fluid drams (6 cubic centimeters) for each 250 
pounds of weight. The worms usually pass for several days follow- 
ing treatment. Purgatives should not be given with this treat- 
