162 THE CANADIAN HOESE 



INFLUENZA. 



Influenza belongs to the class of diseases termed epizootic, 

 which are distinguished by extending over a large tract of 

 country, and attacking a number of horses at the same time. 

 In its nature it resembles an epidemic form of catarrh, but 

 it is essentially different, and is easily distinguished from 

 that complaint by its epizootic character, and the marked 

 prostration and low typhoid form of fever which always 

 accompanies it. It does not affect horses alike in all seasons ; 

 some years it is apt to involve the lungs principally, with a 

 marked tendency to dropsical effusion, whereas in others the 

 liver and digestive organs are chiefly implicated. 



Causes. —It is usually supposed to arise from " atmos- 

 pheric " causes, — some changes which are said to exist in the 

 atmosphere which are ' not easily explained. It occurs 

 mostly in spring or autumn, and is most commbnly seen in 

 over-crowded, ill-ventilated stables. City horses are more 

 liable to it than those in the country, and coarser breeds are 

 more subject to it than the finer breeds. 



Symptoms. — It is early characterised by weakness, a 

 quick, weak pulse, hot mouth, shivering, dulness, watery eyes. 

 The lining membrane of the nose is reddened, accompanied 

 by a watery discharge, which soon becomes thick and puru- 

 lent, accompanied by sore throat and difiiculty of swallow- 

 ing ; the appetite is impaired, and the bowels costive. 

 These symptoms, instead of abating, as in catarrh, increase, 

 the breathing becomes hurried, and there is lifting of the 

 flanks. The low form of fever is characteristic, as also its 

 occurring in spring or fall, and attacking a number of 

 animals in the same way, distinguish it from common 

 catarrh. 



In some seasons the lungs are primarily aflected, and 



