158 SWINE PEACTICB 



fit. This method of medication may be accomplished by providing 

 an oil stove and the medicament vaporized and conducted through 

 a flue into the closed hog house containing the swine. 



Lungs 



ATELECTASIS 



This is a condition of collapse of the lung ; the . absence of air in 

 the lung, and may be either congenital or acquired. The lung of 

 the fetus is always atelectatic before birth. This is one means of 

 determining a still birth, and is often useful as evidence in legal 

 cases. Partial congenital atelectasis may be the result of obstruc- 

 tion of a bronchus with meconium or mucus; it may also be the 

 result of excessive extrathoracic pressure. Acquired atelectasis may 

 be due to compression of the lung by inflammatory exudate (pleuritic 

 effusions), edematous transudate, or forward displacement of the 

 diaphragm. It may also be due to obstruction of the bronchus, the 

 air contained in the air cells being absorbed, permitting them 

 to collapse. This condition may occur in rickets and in pig scour. 



Lesions. — The affected lung tissue collapses and does not crepitate. 

 It is red or reddish-brown in color, feels dry, is tough, and sinks in 

 water. If the condition is of long standing, the affected area be- 

 comes darker in color and is designated cornification. In some in- 

 stances the atelectatic areas become spleen-like, due to the develop- 

 ment of flbrous tissues, and this is termjcd splenization. 



Atelectasis diminishes the breathing capacity, which is the only 

 symptom characterizing the condition. Small areas of the lung will 

 not produce visible symptoms. This condition is usually associated 

 with other disease processes, the symptoms of which mask those of 

 atelectasis. 



Atelectasis occurs in the lung of swine as a result of swine plague, 

 hog cholera, bronchitis, pneumonia, and pleurisy, as well as of other 

 less important diseases. 



EMPHYSEMA 



Pulmonary emphysema has been observed in swine but is not of 

 common occurrence. It is due to conditions that favor the inflation 

 of the lung with excessive quantities of air. Bronchopneumonia is 

 occasionally associated with emphysema. The affected areas are soft, 

 spongy, anemic, and project beyond the surface of the lung. 



