CHAPTER XXIX. 



ENZOOTIC AND EPIZOOTIC DISEASES. 



INFLUENZA. 



Under this term is included three diseases, which every now 

 and then prevail as epizootics in this and other countries, and 

 which have been indiscriminately denominated fever of the 

 horse, epizootis of the horse, nervous fever, putrid fever, in- 

 fectious pneumonia, typhus, &c. 



Falke, however, has reduced these to two conditions recog- 

 nised under the term influenza, — namely, the red disease, for 

 which he has reserved the term influenza, and the other form he 

 has named typhus. Whilst giving due credit to Ealke for 

 endeavouring to abolish the mystification concerning influenza, I 

 feel constrained to state that under the term I can recognise three 

 different morbid conditions, namely — (1) Epizootic catarrhal 

 fever : (2) Epizootic cellulitis or pink-eye ; and (3) Epizootic 

 pneumonia, — all being due to miasmatic or malarial — saprse- 

 mic — organisms generally existent in large horse establishments, 

 and liable to cause epizootic outbreaks under certain alterations 

 of external surroundings, which seem to determine either the 

 receptivity of animals subjected to their action, or a transforma- 

 tion of the vital properties of the microbes. For example, the 

 disease may have been absent in a stable for a period ol time, or 

 until fresh animals are introduced. Then there is an outbreak 

 of the malady amongst the freshly introduced animals, and from 

 which it spreads indefinitely amongst those which have had 

 immediate or mediate contact. Here I think we have an 

 example of the action of a non-contagious facultative parasite 

 becoming transformed during its passage through the animal 

 body into a contagious parasitic microbe, and which at first is 

 thus increased in virulence, but after a period of time the 



