Acute Croupous Pneumonia. Pneumonitis in the Horse. 215 



inclusive 146 cases = 20.85 per month, and in the 5 months from 

 May to September inclusive 62 cases = 12.4 per month. 



Exciting Causes. Nearly all the above causes when acting with 

 unusual force may become direct factors in causation. The ef- 

 fect of a sudden and extreme chill is especially to be feared. 

 Even in cases that are unquestionably due to a microbe as the es- 

 sential cause, the nervous disorder manifested in the chill, and the 

 clogging of the pulmonary circulation in connection with the re- 

 trocession of blood from the surface of the body furnishes the op- 

 portunity for the colonization of the germ. The average horse 

 at pasture will stand with impunity cold storms of rain, snow, and 

 sleet, and transitions from a warm noonday sun to a cold night 

 wind and dew and even frost, but under other conditions of the 

 system, with the fatigue and fret and sudden changes of food and 

 regimen attendant on domestication, or with any derangement of 

 an important bodily function the chill is often the manifest occa- 

 sion of disturbance of the balance of health, and the supervention 

 of pneumonia. Fatigue, a system charged with leucomanies, 

 and a free perspiration, which is suddenly checked by exposure, 

 at rest, to a cold rain , or snow, to a draught between door 

 and window, to immersion in the cold waters of a river, or 

 to sponging with cold water is quite liable to cause pneumonia. 

 An unduly heavy winter coat, an individual peculiarity or deter- 

 mined by a cold environment in autumn often predisposes strongly 

 to such dangerous chills, by the frequency and profuseness of the 

 perspirations and general relaxation of the system. Clipping of 

 such subjects is a true hygienic measure though it entails the 

 need of extra care in blanketing. Again in the animal that has 

 already suffered from disease of the respiratory organs these 

 chills are more dangerous factors. 



Direct irritation by inhalation of smoke and other products of 

 combustion ; or acrid or irritant gases or dust ; by the drawing of 

 food by aspiration into the lungs (as in paralysis of the larnyx or 

 pharnyx, choking, apoplexy, vomiting, etc.); by pouring irri- 

 tant or insoluble drugs (oil, lard) through the nose ; by the pres- 

 sure of neoplasms (actinomycosis, tubercle, glanders, cancer) ; or 

 by the presence of parasites (strongyles, distomata, echinococci, 

 linquatulas. 



Pneumonia from Contusion of the chest, fracture of a rib, or 

 puncture or laceration of the lung is recognized. 



