ly^ Influenza of Horses. 



braiie from other causes, while pectoral influenza may easily 

 be confounded with sporadic croupous pneumonia. Although 

 the edematous infiltrations of the subcutis, as well as the 

 tendonitis and the tendo-vaginitis, also the icteric discolora- 

 tion and chemotic infiltrations developing in association with 

 the conjunctivitis, are quite characteristic of influenza, these 

 s}^nptoms are not infrequently absent, especially in the early 

 cases of an outbreak. In such cases the infectious character 

 of the disease, and its rapid spread among horses, reveals the 

 nature of the affection. In practice it is advisable therefore 

 to suspend diagnosis in the first cases, until the appearance 

 of new cases, or dependable data disclose the infectious nature 

 of the disease, or until characteristic symptoms develop, or 

 on the other hand, until the infectiousness of the affection may 

 be excluded. In consideration of these diagnostic difficulties 

 every suddenly appearing catarrhal affection, and particularly 

 every croupous pneumonia, should be considered as if it were 

 an attack of influenza, that is, as an infectious disease. Ac- 

 cordingly an immediate isolation of the affected animal is in- 

 dicated in all such cases. Influenza is distinguished from 

 the non-infectious catarrhs, principally by the fact that in the 

 former the catarrhal manifestations are preceded by high fever 

 of sudden development, while in the latter the catarrhal symp- 

 toms are rather latent and develop only mth slight rises in 

 temperature. 



If influenza has been established in a stable, or if the dis- 

 ease is present in nearby localities, all febrile affections should 

 be considered as suspicious of the disease. Further, as the 

 febrile rise of the temperature represents the first sjTuptoms 

 of influenza, it is advisable in order to separate immediately 

 the newly affected animals, to take the temperatures of the 

 horses in the infected or endangered stables systematically 

 twice a day. A rise in the temperature of two degrees or over 

 is sufficient to indicate the probable presence of the disease. 



Infectious anemia may possibly be mistaken for the 

 catarrhal form of influenza, especially when it is associated 

 with severe intestinal disturbances. The condition of the blood 

 affords a means of differentiation since in anemia it coagulates 

 incompletely, at the same time the serum frequently appears 

 opalescent and of a more reddish color (Vallee). The appear- 

 ance of pneumonia, or pleuro-pneumonia, or the development 

 of similar symptoms in other horses of the stable would be 

 indications of influenza; on the other hand, rapid emaciation 

 and cachexia, without organic affection, as well as the pres- 

 ence at autopsy of a greatly enlarged spleen, would suggest 

 the presence of infectious anemia. Strangles may also" be 

 considered in the beginning of the affection, from the standpoint 

 of a differential diagnosis; in this, however, the swelling and 

 suppuration of the lymph glands reveals the nature of the 

 affection. 



