198 CLINICAL VETKRINARV MEDICINE AND SURGERY. 



rule patients become convalescent between the tenth and fifteenth days> 

 and resume work a week or two later. 



Instead of terminating in resolution, pneumonia may assume the 

 chronic form. Sometimes a few areas of necrotic parenchyma become 

 surrounded by an irdurated zone, and produce centres communicating; 

 with the bronchi, into which they pour infectious material, facilitating 

 the spread of contagion by animals to all appearance cured. In general,, 

 however, such animals show capricious appetite, cough, do not attain 

 hard condition, and soon become exhausted by work — symptoms usually 

 referred to broken wind. Such chronic lesions when limited in area 

 may long persist without producing appreciable disturbance, though at 

 last bringing about acute fatal pulmonary or pleural complications. 



When the disease has already affected a certain number of animals, 

 diagnosis offers no difficulty. Among the initial symptoms two are 

 particularly important and significant, viz. the rapid onset of fever and 

 the marked acceleration of breathing. A certain method of recognising 

 the onset of disease is to note the night and morning temperatures of 

 animals exposed to infection. The first cases may be mistaken for 

 the abdominal form of influenza, but the regularity with which the 

 principal symptoms appear in almost all patients, and the constancy of 

 the pulmonary affection (whose symptoms dominate all the others), 

 soon remove ^any uncertainty. I have drawn attention to the difficult}- 

 in differentiating between infectious and simple pneumonia. I do not 

 share the opinion of authors who suggest that these two forms are at 

 first clearly distinguishable one from the other. Apart from the history 

 — which of itself is a useful guide in the absence of well-marked 

 clinical symptoms — the contagious character of the one form is soon 

 shown by the number of cases which occur. Diagnosis is confirmed 

 by the course of the disease, and b}- its contagious or sporadic cha- 

 racter, as the case may be. 



At the present time the differential diagnosis of these two varieties 

 of pneumonia cannot be finalh' established either b}- bacteriological 

 examination or by cultivation methods. 



The prognosis of contagious pneumonia is grave. The mortality 

 varies widel}- according to the time of year, character of the outbreak, 

 and surroundings of the affected animals, but not infrequently attains 

 to 20 per cent. You have seen that numbers of secondary affections 

 occur, rendering the outlook graver. Loss of appetite, prolonged 

 intense fever (^i*^ C. — 105-8° F.), and continual lying down (decubitus) 

 are all gra^•e symptoms. Epidemics of pneumonia are not of equal 



