16 DEPARTMENT OF AGRICULTURE. 



SIGNS OR SYMPTOMS DURING LIFE. 



It is necessary to draw special attention to the fact that in States or on farms where 

 the lung plague has never before existed it is the more readily recognized, in the earlier 

 stages, as in case of other epizootics, the more complete the history. The fact that cattle 

 have been recently purchased, or that drift cattle have crossed the farm or prairie, the 

 knowledge of the existence of such a disease in adjoining States or farms, or of sick cattle 

 being sold by auctions or in the markets, are all most important elements in guiding to a 

 correct conclusion as to the nature of the disease. 



Very frequently an animal is bought, placed among others, dies, and the remaining 

 cattle cough, get out of condition, and some soon sicken. The purchased animal may show 

 no signs of illness, however ; it may be suffering from a latent form of the disease, or it 

 may be in the convalescent stage, and gaining flesh daily. 



A dairyman, especially in a large town, may have had pleuropneumonia among his 

 cattle, which had subsided, and his stock, composed of animals that had withstood the dis 

 ease, might be regarded as healthy. But some still discharge a degree of poison, and infect 

 the atmosphere, and a newly bought animal dates the period of the incubation of the mal 

 ady from the moment it entered the stable. 



The incubation of the disease may be said to vary from eight or nine days to three or 

 four months. In the inoculated malady the exudation commences sometimes as early as 

 the fifth day, more commonly about the ninth or twelfth, and it may be as late as thirty 

 or forty days. In the disease communicated by cohabitation, a cough, to which very 

 special attention was drawn by the experiments of the French commission on contagion, 

 supervenes about the ninth day and later. It is usually noticed by cow-feeders, who buy 

 cows which have just calved, that they drop with the disease about the time they should 

 manifest oestrum, that is to say, six weeks after their admission. 



There are false and true periods of incubation of the lung plague. And this has been 

 overlooked too much in descriptions of the disease. The actual incubation is from the 

 period of contamination, by contact or inoculation, to the moment that a special morbid 

 change commences. Our means of observation have not been exact enough, and it is very 

 desirable that thcrmometric observations should be made on experimental animals, and 

 these, with the ordinary phenomena derived by auscultation, etc., will assure us of the 

 actual length of the stage of the lung disease which is unattended by any appreciable sign. 

 We shall then know the true period of incubation. The false periods of incubation are 

 those derived by persons from observing an animal to sicken, say four months after pur 

 chase, and drawing the conclusion that this period represents the incubation stage. As a 

 rule in such cases, two or three latent instances of the disease have preceded the obvious 

 one. Then, again, the period of incubation is not usually stated correctly by farmers, as 

 they overlook the first signs of the disease, which occur several days before cessation of 

 appetite, secretion of milk, &c. 



Invasion of the lung plague is characterized by local phenomena which most frequently 

 show themselves by the cough already referred to. With one of Casella s self-registering 

 thermometers it will be found that in an infected herd some animal or animals in apparent 

 health, which no one suspects to be diseased, will manifest a temperature of 104 or 105 

 Fahrenheit. I have never seen a case in which, when the temperature was thus elevated, 



