THE ROUNDWOEMS OF DOMESTIC SWINE. 37 



suggest the possibility that development occurs without an inter- 

 mediate host. From the fact that the embryos are well developed in 

 the uterus before oviposition, it would seem that but little time is 

 required for incubation, and the thickness of the shell would indicate 

 the necessity of the gastric juice of the host to dissolve the shell and 

 liberate the embryo. 



PREVENTIVE MEASURES. 



In the absence of knowledge as to the life cycle of the parasites, no 

 prophylaxis or treatment specially adapted to the case can be formu- 

 lated. The following general prophylactic measures are suggested: 



1. Hogs suffering from loss of appetite or failing to fatten under 

 proper food and hygiene should be examined for evidence of infection 

 by killing one or two and looking in the stomach for worms; or, where 

 practicable, the feces of the entire herd may be examined micro- 

 scopically. 



2. Those swine found infested with stomach worms should be 

 isolated from noninfested or presumably noninfested swine in clean 

 pens, and the dung removed daily and mixed with quicklime or 

 disposed of by carting it to places to which hogs do not have access. 



3. The noninfested swine should not be allowed to remain in the 

 same pens formerly occupied by the infested animals, but should have 

 clean quarters. The old pens should be thoroughly disinfected with 

 lime after removing the dung and burning over the ground where 

 feasible. 



MEDICINAL TREATMENT. 



Youatt (1847c), referring to Spiroptera strongylina, recommends 

 turpentine and salt with the food for treating these worms. Coal-tar 

 creosote, gasoline, and copper sulphate have been found more or less 

 efficacious in treating stomach worms (Hsemonchus contortus) in sheep, 

 and similar treatment might be tried on pigs (see Bureau of Animal 

 Industry Circular 102). Santonin and calomel, 3 grains each per 

 hundred pounds of body weight, given after a fast of 12 to 16 hours, 

 is another remedy which deserves trial. 



Whatever drug is used should first be given in small quantities and 

 tried on a few of the most heavily infested swine, the size of the dose 

 being increased as occasion demands. 



