BRONCHO-PNEUMONIA OF SUCKING CALVES. 357 



Pathogeny. At the outset of these attacks of broncho- puhnonary 

 disease, a careful bacteriological examination of the organisms to be 

 found in the discharge of bronchial mucus leads to the discovery of 

 bacilli which do not stain with Gram, and which resemble varieties 

 of the colon bacillus ; in other cases of streptococci. At a later stage, 

 when the animal has become weak, micro-organisms are present in 

 much greater variety. Nocard found in lung abscesses the bacillus 

 of epizootic lymphangitis. It seems that the development of various 

 lesions in the thoracic cavity may be due to auto-infection, i.e., to 

 the penetration from the intestine of germs which, after passing 

 through the circulation, establish themselves at some point in the 

 lung. The pleura is attacked at a later period as a consequence of 

 continuity and contiguity of tissue. 



In a similar way pericarditis and even valvular endocarditis may be 

 l^roduced. 



Symptoms. The symptoms are similar to those of all forms of 

 broncho-pneumonia. Where diarrhoea has been neglected, the condi- 

 tions may apparently improve without evident cause, whilst the respi- 

 ration becomes more frequent. The patient soon suffers from cough, 

 and in a few hours the existence of broncho-pneumonia is clearly 

 apparent. Acceleration of breathing is the dominant symptom. The 

 respirations may rise to fifty to sixty per minute, at which they con- 

 tinue, while fever sets in. On percussion the thorax may appear of 

 normal resonance throughout; but when pleural lesions and exudates 

 exist, resonance gives place to partial or complete dulness. Should 

 pericarditis or small cardio-pericardial adhesions exist, they may escape 

 observation, but if the exudate is abundant or the adhesions multiple or 

 of large size the usual symptoms of pericarditis develop progressively. 



On auscultation the respiratory murmur is always found to be greatly 

 exaggerated in the healthy parts, usually the upper portions of the lung. 

 On the contrary, it is attenuated or suppressed in the afiected regions. 

 The other signs vary greatly, according to the extent, intensity, and more 

 or less advanced condition of the lesions. Crepitant and bronchial rales, 

 blowing respiration and tubal souffles, etc., are among the symptoms. 



The duration of the disease varies ; some patients may be carried oft' 

 in five or six days, while others survive for one or two months, or even 

 longer. A few recover, but they remain thin, puny, and atrophied, and 

 are not worth keeping alive. 



Lesions. The lesions extend to the bronchi, the pulmonary tissue, 

 and sometimes the pleura and pericardium. They consist in lesions of 

 difi'use broncho-pneumonia, pleurisy with false membranes and parieto- 

 pulmonary adherences, and pericarditis with partial cardio-pericardial 

 adhesions. 



