222 SWINE PKACTICE 



Prevention of pig scour is far more satisfactory than the treatment 

 of affected animals. Breeders should be advised to keep pregnant 

 sows in clean quarters, particularly during farrowing time. Pigs 

 may be immunized against the various microbian agents cited as 

 probable causative factors in pig scour, and the practice of immuni- 

 zation of small pigs against scour may be the proper solution of 

 overcoming the losses incidental to this malady. 



PULMONARY ASCARIDIASIS 



There has been an unusual loss of little pigs during the last few 

 years, more especially during the last two years, in the United States, 

 and from investigations it is apparent that these losses have been 

 largely due to an embolic pneumonia of parasitic origin. Many 

 swine breeders have lost fifty per cent of their pig crop, and instances 

 have been recorded where 80 to 90 per cent of pigs have died as a 

 result of the invasion of the lung with parasites. Loss occasioned by 

 these parasites is not only from the death of the little pigs but from 

 the loss of condition of shotes and larger swine. 



Etiology. — The specific cause of pulmonary ascaridiasis is the larval 

 form of the Ascaris suum. The life cycle of this parasite according 

 to the investigations of Stewart, Ransom, and Foster, is briefly as 

 follows : The ovum of the ascarid is eliminated from the adult in the 

 intestine of the swine and passes out with the feces. The ovum 

 incubates outside the animal body. The time required for it to pass 

 through the various stag'es and become infective depending upon the 

 temperature. It requires about three weeks at a temperature of 

 75° F. and two weeks at a temperature of 90° F. It will not be- 

 come infective when incubated at body temperature; therefore it is 

 necessary for the ovum to pass out of the body of the swine before il 

 successfully incubates. 



The infective incubated ova are ingested by swine on their food 

 or in their drink and may be obtained by the suckling pig from the 

 teat of the sow. The ova may also be obtained by rooting in infested 

 pens. After the incubated ova are ingested they pass with the food 

 into the stomach but are not liberated from their capsule until they 

 reach the intestine. After emerging from their encysting capsule 

 they begin migration into the tissues. "Within four or five days some 

 of them are found in various tissues but only those that reach the 

 lung successfully develop, those remaining in other tissues ultimately 

 perish. When the larval stage is completed the larvae pass up the 



