The Lung Plague of Cattle. 



may be altogether due to the environment ; and that the 

 doctrine of contagion is either founded on insufficient 

 data, or true only in a restricted sense and entirely sub- 

 sidiary to the generally acting causes. But the malady 

 as known to veterinarians of to-day is always and only 

 the result of contagion or infection, therefore we should 

 select a name better adapted to set forth this character 

 without the risk of misleading. This we have in the 

 Imng Plague of Cattle, the near counterpart of the Imngen- 

 sevclie by which it has been long known in Germany. 

 The old term Pulmonary murrain is equally good. 



The German Lungenseuche is especially apposite, the 

 real meaning being Lung-contagion, which conveys the 

 idea of transmission by contagion only. 



Definition. — A specific contagious disease peculiar to 

 cattle, and manifested by a long period of incubation (ten 

 days to three months), by a slow, insidious onset, by a low 

 type of fever, and by the occurrence of inflammation in 

 the air-passages, lungs, and their coverings, with an ex- 

 tensive exudation into lungs and pleurae. 



History. — As in the case of all genuine plagues, small- 

 pox, cholera, rinderpest, aphthous fever, etc., we know 

 nothing of the original source of the lung-fever contagium. 

 We know the disease only as it is introduced into a 

 country or herd by a diseased animal or some of its in- 

 fecting products. In ancient as in modern times, in the 

 Old World as in the New, the malady can ever be traced 

 in connection with the aggregation of cattle in herds 

 made up from different districts and countries. Aristotle, 

 writing three hundred and fifty years before Christ, says . 

 " The cattle which live in herds are subject to a malady 

 during which the breathing becomes hot and frequent. 

 The ears droop and they cannot eat. They die rapidly, 

 and the lungs are found spoiled." Here the facts that 

 cattle alone suffered, that large herds suffered most, that 

 the lungs were the seat of the diseased changes, and that 



