DISEASES OF THE BESPIRATOEY ORGANS. 47 



Influenza is an epidemic diseftse, wliicli is characterizecl by catarrh of 

 the respiratory, and often aJso of the digestive organs. Its attack is sudden, 

 great and rapid weaJoiess is developed, and fever of greater or less inten- 

 sity is associated. The disease may occur among dogs, uninfluenced by 

 the age of the animal or the season of the year. 



Causation . — Of the exciting causes of influenza little is known. It has 

 not been established thatlihere is any connection with atmospheric condi- 

 tions. An essential diflference is noted between this and the non-epidemic 

 catarrh, since the latter affection is traceable to " catching cold," and 

 follows exposure. Influenza on the other hand, prevails when catarrhal 

 affections are rare, and it may appear in any season of the year, hot and 

 dry, or cold and damp. Some authors assume it to be contagious, others 

 refute the theory, and the question has remained a mooted one. 



Inl872 an influenza prevailed widely among horses, and in New York 

 alone attacked about sixteen thousand; no special causes for it were 

 ascertained. 



Symploms . — The frequent location of the disease is upon the mucous 

 membrane of the respiratory organs, it being more rarely affected than 

 that of the stomach and intestines. 



The onset of the disease is generally sudden, marked by lassitude and 

 shiverings, indicative of a chill. In severe cases fever soon manifests 

 itself assuming a remittent type. The pulse varies in character being full 

 and frequently irregular. The affection of the mucous membrane of the 

 respiratory organs is indicated by symptoms essentially of a catarrhal 

 nature. Most frequently is observed at first sneezing, the eyes reddened 

 and watery, the nasal membrane swollen and reddened. 



In some cases the throat becomes sore, and the catarrhal inflammation 

 extends to the larynx and bronchi, the invasion of these parts being evinced 

 by hoarseness an4 a tendency to cough. Not unfrequently in the very begin- 

 ning, a cough sets in dry and disturbing, occurring in paroxysms frequently 

 Inducing vomiting. The expectoration is usually scanty but sometimes 

 becomes more abundant later in the disease. While the physical exami- 

 nation of the chest is negative, the breathing frequently becomes hurried 

 and at times the restlessness of the animal will indicate pain, probably of 

 a pleuritic character. The digestive organs are very often affected. Loss 

 of appetite, a coated tongue, thirst, and not infrequently vomiting and 

 diarrhoea accompany the disease. At times however, constipation exists. 



Prostration is often very marked, the animal is dull, heavy, and sleepy. 

 It will be frequently noted that in walking about he will act stiff and lame 

 and sometimes his movements will appear painful. 



