33S INFLUENZA 



due to oedema caused by passive congestion. L,ess frequent!}' 

 the swellings are of an inflammatory nature. The swelling of 

 the extremeties causes the gait to be stiff and unwieldy. 

 Inflammation of the sheaths of the tendons is sometimes 

 observed. 



The respiratorj' mucosa are congested. At first there is a 

 serous and, later on, a muco-purulent discharge from the nose, 

 slight swelling of the submaxillary glands, moderate accelera- 

 tion of respiration and a cough. As a rule the animal becomes 

 emaciated during the course of the disease, pregnant mares 

 may abort. 



The average duration of the disease is from six to ten 

 da3's, although severe cases may run for two or three weeks 

 and very mild cases may recover in from three to six days. 



In certain cases complications may arise such as cardiac 

 debilit}-, grave cerebral symptoms, severe gastro-intestinal 

 inflammation, laminitis and petechial fever all of which have 

 been described as accompanying complications. 



The mortality \'aries at different times and in different 

 places. The average appears to be from 0.5 to 4 per cent. 

 Dieckerhoff saw a loss of 4 per cent among 1,700 horses: 

 Aureggio, one of 3 per cent among 800 horses ; Friedberger, 

 one of 9 per cent ; and Siedamgrotzkj-, one of 10 per cent. It 

 is stated that in 1872, in Philadelphia, 7 per cent of 30,000 

 infected horses died. 



J^ 256. Morbid anatomy. The principal tissue changes 

 of influenza are met with in the organs of digestion. The 

 mucous membrane of the pyloric portion of the stomach and 

 of the intestines is h^-peraemic, swollen and sprinkled with 

 slight hemorrhages. The submucosa is yellowish in color and 

 infiltrated with a gelatinous substance causing the membrane 

 to form thick somewhat translucent elevations containing a 

 fluid which coagulates. Peyer's patches are enlarged especially 

 those in the neighborhood of the ileo-caecal valve. The 

 mucous membrane of the mouth and sometimes that of the 

 pharynx show similar changes. 



The mucous membrane of the upper air passages is 

 hyperaemic and swollen. In rare cases, the mucosa of the 



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