108 POULTRY DISEASES AND THEIR TREATMENT. 



or considerable loss will follow from continued exposure of the 

 flock. 



Prognosis. — This disease is usually fatal in a few minutes or 

 hours after its symptoms are noted. According to Salmon the 

 patient sometimes develops pneumonia. 



Pneumonia. 



This disease is a step beyond congestion of the lungs. The 

 ■vessels are not only distended but liquid escapes through their 

 walls and coagulates in the air spaces. The kmg of a chick 

 dead of pneumonia is dark colored and firm and heavier than 

 water. A normal lung floats but a lung filled with this coagu- 

 lated serum sinks. 



Diagnosis. — The symptoms resemble those of congestion of 

 the lungs. Salmon gives the following symptoms : "The breath- 

 ing is rapid, difficult and painful. There may be coughing with 

 discharge from the mouth or nostrils of thick, adhesive mucus, 

 grayish or yellowish in color or tinged with blood. The bird 

 stands with ruffled plumage, drooping wings, head drawn in, 

 and every appearance of severe illness. There is loss of appe- 

 tite from the first, with thirst and constipation. 



On examination of the lungs after death one or both of these 

 organs are found dark in color, engorged with l)lood and solidi- 

 ;fied. The pneumonia may take either one of two forms. There 

 may be what is known as broncho-pneumonia, in which case the 

 inflammation affects more particularly the bronchi and the lung 

 is not much solidified. The bronchial tubes in this case are 

 more or less filled with thick mucus and exudate. In the other 

 form, called croupous pneumonia, the tissue of the lung is prin- 

 cipally affected. It is then that the lung is solidified by the 

 filling up of the air-cells. A piece of lung so affected, if dropped 

 into a bucket of water, sinks to the bottom, while healthy lung 

 tissue will float. The bronchial tubes and air-sacs are also in 

 some cases filled with a thick, yellowish fibrinous exudate which 

 blocks up these air-passages and becomes partly solidified." 



Btiology.~The cause of pneumonia in birds is not known. 

 Salmon suggests that it may be caused in birds as the similar 

 disease is known to be in some of the mammals and man. Rob- 

 inson briefly summarizes Salmon's statement as follows: "He 

 says it is supposed that to produce pneumonia there must be 

 ^^ith the causes that produce congestion of the lungs the agency 



