156 SWINE PRACTICE 



BRONCHIAL AND PULJIONARY STRONGYLOSIS 



Pulmonary strongylosis and bronchitis are very common in swine 

 in the United States; however, the infestation is only rarely of 

 sufficient extent to produce serious damage. The lungs from a thou- 

 sand swine were inspected in a Kansas City abattoir and sixty per 

 cent of them contained pulmonary Strongyli in such numbers that 

 the lesions could readily be observed by gross examination. 



Etiology. — Metastrongylus apri is the causative parasite of por- 

 cine pulmonary strongylosis. It is a white or brownish-white thread- 

 like worm from one inch to one and a half inches in length. The 

 adults inhabit the middle-sized and small bronchioles, usually in the 

 posterior superior part of the lung, although they may be found 

 elsewhere in the lung. The ova are carried out from the lung in 

 the discharge and may pass out directly or pass into the pharynx 

 and be eliminated in the feces. The exact life cycle is not known, 

 but it is probable that the ova hatch and undergo several moults 

 before regaining the animal body. The parasites gain entrance 

 to the animal body in the food or water, infestation of swine being 

 accomplished. Young pigs are most susceptible; however, the para- 

 sites have been identified in swine of all ages. After the parasites 

 gain entrance to the animal body they begin to migrate, some of 

 them ultimately reaching the bronchial tubes. The exact route of 

 migration is still a disputed question, but they pass either by way 

 of the pharynx through the larynx to the bronchial tubes, by way of 

 the blood stream, or directly through the tissues. 



Lesions. — The principal lesions in swine are found in the posterior 

 lobes and in the superior part of those lobes. At first the lesions are 

 confined to centers, or foci, which are coneshaped and usually atelec- 

 tatic, though they may protrude and be of a doughy consistency. 

 In a later stage these foci are found to contain mucopurulent, puru- 

 lent, or even caseous substances in varying quantities in addition 

 to from one to many Strongyli and their ova. Similar discharges 

 will be found in the bronchial tubes and even in the trachea, and 

 occasionally disintegrated vermes and their ova will be found in 

 the expectorate. There may be bronchiectasis, but this condition is 

 not common. The visceral pleura may show evidence of chronic 

 inflammation. 



Symptoms. — The period of incubation varies from four to eitrht 

 weeks. Although this condition is very prevalent, the infestation 



