CONTAGIOUS PLEURO-PNEUMONIA 435 



this country, it had become widespread, and the 

 deaths very numerous. 



In all probability another reason for its infectious- 

 ness having been overlooked may be found in the 

 fact that the lung disease does not manifest itself in 

 recognisable symptoms, for at least six weeks after the 

 animal has become infected. 



Instances have been cited tending to show a 

 period of incubation or hatching for twelve months, 

 but undoubtedly the average period of incubation in a 

 primary and uncomplicated case of epizootic pleuro- 

 pneumonia is six weeks. 



SYMPTOMS. The first and earliest symptom is a 

 cough of a peculiar short, sharp, and dry character, 

 increase of temperature, pulse full and quick, breath- 

 ing quickened, nostrils dilated, bowels constipated, 

 a slight grunt at expiration, and marked tenderness 

 when spine is pressed. On recourse to auscultation 

 and percussion, certain sounds are heard which in- 

 dicate the existence of bronchial disturbance and 

 lung disease. As the disease advances the tempera- 

 ture increases, the grunt becomes louder, and the 

 breathing distinctly abdominal. 



CAUSES. The cause of this, like all other specific 

 diseases, is the entrance of the living specific organism 

 into the lungs. Unlike many other specific or germ 

 diseases, it cannot be propagated by inoculation of the 

 diseased exudates of the lungs, neither can it be 

 propagated by ingestion, that is by the introduction of 

 the virus into the stomach in food or drink. It can 

 only be propagated in one way, and that is by In- 

 halation, inhaling the breath of the living affected 

 animal, and the moment the animal dies the infection 

 or power to infect ceases. 



