34 DISEASES OF POULTRY. 



beak is kept open in order to breathe, the sight is de- 

 stroyed by inflammatory products, the eyes are often 

 closed and bulging from the head, the breathing is very 

 difficult, a thick, sticky discharge escapes from the 

 nostrils, the subjects are emaciated, prostrated, sleepy 

 and perhaps unconscious. When these severe symp- 

 toms appear, the strength is soon exhausted and death 

 follows. 



Contagious catarrh spreads rapidly through a flock, 

 affecting the greater part of the birds and causing the 

 death of a variable proportion according to the viru - 

 lence of the contagion. It is always a very serious 

 disease and is difficult to eradicate. 



Causation. — That roup is a contagious disease 

 admits of no question. Its origin in a flock can fre- 

 quently be traced to the introduction of a bird from 

 some other premises where the disease exists. Often, it 

 is contracted by exposure to affected birds at shows, 

 or to the contagion clinging to coops, houses or 

 infected runs. Many writers teach that roup' may 

 originate from exposure to cold or draughts of air. 

 This prevalent opinion is probably accounted for by 

 the fact that the first stages of roup are almost identical 

 in their symptoms with simple catarrh or a common 

 cold. It is not likely, however, that such exposure is 

 sufficient to produce roup. Contagious diseases are 

 caused by parasites, each specific disease having its 

 particular species of animal or vegetable life to call it 

 into existence, and without its particular parasite the 

 disease cannot be developed. It is, therefore, logical 

 to conclude that if the germ or parasite of roup is not 

 already infecting a given poultry yard, the disease will 

 not appear until this parasite is introduced. Colds and 

 catarrh may become aggravated and even fatal by neg- 



