DISEASES OF SWINE 531 



turn to the normal, but may go through other diseased changes. In 

 some cases the effect is to enlarge the bronchi or to cause saculation. 

 Method of Infection. The life history of the lung worm is not 

 fully known. In most domestic animals infection with lung worms 

 depends largely on the humidity of the soil, and is more prevalent 

 on swampy pastures containing ponds and stagnant water than it ia 

 on high ground. This disease is more prevalent during wet seasons. 

 Lung worms are often present in pigs when kept under the best pos- 

 sible conditions. The eggs are laid in the bronchial tubes. Before 

 they hatch it seems necessary for them to be expelled by coughing, 

 and undergo a part of their development outside of the body. Just 

 what these changes are is not known. In all probability the pig be- 

 comes infected through the food supply, by rooting in the mud and 

 by inhaling the immature form in the dust that may accumulate 

 about the sleeping quarters and pens, as a result of the mud carried 

 on the bodies of the animals. 



Symptoms. The disease is largely confined to pigs. The first 

 symptoms begin as a cough, occurring upon leaving the bed, after ex- 

 ercise and after eating. In badly infected cases the paroxysm of 

 coughing is quite severe, beginning slowly and becoming harder 

 and harder, and finally the pig will put the nose on the ground and 

 press hard while coughing. The paroxysm ends by the expulsion 

 of some mucus or by vomiting. This is referred to frequently in 

 the journals as whooping cough in pigs. The cough may become 

 frequent and persistent, and is generally spoken of as chronic. In 

 the majority of cases the infection is so slight that the presence of 

 the lung worm is not suspected by the owner. The appetite remains 

 good in such cases and the thriftiness of the pig is not interfered 

 with. Death seldom occurs and as the pig grows and thrives, it 

 gradually recovers from the affection. 



Treatment. Keep the pig in a healthy, growing condition. 

 Conditions in pastures and pens should be as hygienic as possible. 

 Drinking water should be pure, and all ponds and mud holes 

 drained or filled. Clean watering troughs and floors are necessary. 

 The sleeping quarters should not be dusty. Medicine is of little 

 value. Feed a highly nutritious ration, and wait until age will give 

 the necessary strength and resistance to overcome the disease. 

 (Ind. B. 100.) 



Young, growing pigs are sometimes attacked by lung worms, 

 which bring about an inflammation of the air passages. The most 

 important symptoms produced by these are general unthriftiness, 

 and a hard cough. Old hogs are rarely attacked and the younger 

 hogs usually recover. The worms that produce this trouble are very 

 small (one-half to 1 inch in length) and examination of the frothy 

 expectoration of sick hogs or of the lungs after death is usually re- 

 quired to make a positive diagnosis. In this disease there is an en- 

 tire absence of symptoms of acute illness such as usually accompany 

 an attack of hog cholera. This fact coupled with the cough would 

 point to lung worms; examination of the lungs and expectoration 



