PNEUMONIA 591 



passages. It is a disease which may occur at any season of the 

 year, but is especially common in the winter and spring. It is 

 much more common in fat, plethoric animals than it is in the lank, 

 thin hogs. Overcrowding and overheating, followed by exposure 

 to cold rainy weather, is a most fruitful cause for pneumonia. 

 Animals coming out of a hot nest into the raw bleak winds that 

 prevail in March and April are especially likely to develop bronchi- 

 tis or pneumonia. 



Pneumonia is especially common in animals that have been sud- 

 denly changed from sanitary quarters to a drafty, ill-ventilated 

 shed. This is very commonly seen in the winter months, when 

 hogs are purchased at a pubHc sale and moved to a neighboring 

 farm and placed in a pen where they are overcrowded and liable to 

 become overheated. The home herd that is used to this misman- 

 agement may not be affected, as they have become gradually accus- 

 tomed to it. The newly purchased animals are unable to stand the 

 sudden change and often develop a fatal pneumonia and die. In 

 like manner, shipping of animals in open stock cars in the winter 

 months is often followed by pneumonia. 



Hogs not infrequently develop a pneumonia as a result of chill- 

 ing after passing through a dipping vat. Inhaling of irritating 

 gases and vapors is another common cause of the disease. Unskil- 

 ful drenching, resulting in the passage of the fluid down the wind- 

 pipe rather than the food passages, is also liable to be followed by 

 pneumonia. 



Pneumonia is a very common compUcation of other diseases in 

 swine. This is especially true in hog-cholera and in swine plague. 

 Hog-cholera is comphcated by a pneumonia in perhaps 50 per cent, 

 of cases. What was formerly known as swine plague is, in reality, 

 hog-cholera with a complicating pneumonia. Lung worms also 

 frequently set up small areas of pneumonia in the lungs. This 

 form of pneumonia is more common in Europe than in the United 

 States. 



The specific cause of pneumonia is a small germ which is known 

 under the name of the pneumococcus. It is a small lancet-shaped 

 organism, and is found in the nose and throat of healthy animals. 

 It is unable to produce disease unless the resistance of the animal 

 be lowered in some manner, as by exposure to chilling winds. This 



