SHORTHORN BREEDERS. 347 



stages. First, the incubative or hatching stage, secondary or middle stage, and the- 

 fatal stage. The incubative stage is when the disease is making its way silently 

 into the system without any external svmptoms. This we know from the fact that 

 animals slaughtered for the market, apparently in good health, and had exhibited 

 no symptoms of any disease when killed, have shown considerable disease in one 

 or both lungs when dead, and to this difficulty of recognizing the affection in its 

 first stage may be ascribed much of the fatality of pleuro-pneumonia, as before 

 any means of preventing its spreading, or curing the diseased ones, can be adopted, 

 itjla past medical aid, and has acted as a focus of contagion to the rest of the herd. 

 This stage may last some days, varying from forty days to two months. In the 

 second stage symptoms begin to develop themselves, though at first slight. The 

 animal looks dull and dispirited, and rumination is suspended ; a slight shiver or 

 shaking, probably a little cough, with slight accelerated breathing ; if a milker, 

 the supply of milk is suspended. These will be the only symptoms observed, but 

 as the disease advances the cough becomes louder, the pulse is quickened, usually 

 numbering from 80 to 100, and the temperature rises, and all the appearance of 

 acute fever sets in ; the breathing becomes accelerated, and with each respiration, 

 the animal gives a peculiar, low grunt ; the secretions of milk gradually dimin- 

 ish from day to day, until entirely suspended. Digestion is now interfered with, 

 and constipation, sometimes attended with tympanitis, is present. In the last stage 

 the symptoms are distressingly aggravated. The grunt is changed to a loud moan 

 of pain; the breathing is laborious ; offensive diarrhrea sets in ; the pulse is almoBt 

 imperceptible ; the legs and horns get cold, the abdomen filled with gas, and death 

 quickly takes place. In auscultation, or sounding the chest, which is applying the 

 ear to the sides of the chest, over the region of the lungs. To do this effectually it 

 is necessary to be acquainted with the sounds in the healthy lung. In health, a 

 peculiar sound is heard at each respiration. This is called the respiratory mur- 

 mur, and is caused by the air passing into the minute structure of the lungs. In 

 the secondary stage, or, in fact, when the disease commences, these sounds change, 

 and are not heard at all, the lungs becoming impervious to air. Percussion, or 

 striking the sides of the chest between the ribs with the ends of the fingers, assists 

 us in detecting the lung which has become solid or hepatized. In health, a hollow 

 sound is emitted, but when hepatized a sensation is given to the hand as if it had 

 struck a solid body. On examination after death the lungs (or oftener one lung) 

 are found enormously enlarged — so much so, in some cases, as to fill up the cavity 

 of the chest. Upon cutting into the substance of the lung, which in health is light 

 and spongy, the cut edges will have a veined or marbled appearance, having 

 abscesses of various sizes, filled with pus or matter. The cavity of the chest is 

 filled with lymph ; strings of it cover the pleura and that portion of it lining the 

 ribs, and extending from one to the other. These are infe( tious as well as con- 

 tagious diseases — infectious from having the qualities of infection, the thing which 

 taints, poisons or corrupts, communicating it from one to another ; contagious 

 from containing or generating contagion that may be communicated by contact 

 from poisonous excreted matter or poisonous exhalation, the containing of which 

 may be propagated and communicated from one to another. As to the causes of 

 those infectious and contagious diseases, all writers on the subject seem to agree^. 



