504 INFLUENZA 



debility, grave cerebal symptoms, severe gastro-intestinal 

 inflammation, laminitis and petechial fever, all of which have 

 been described as accompanying complications. 



The duration of the disease is from six to ten days, although 

 severe cases may run for two or three weeks and very mild 

 ■cases may recover in from three to six days. 



The mortality varies at different times and in dift'erent 

 places. The average appears to be from 0.4 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 Siedamgrotzky, one of 10 per cent. It 

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

 infected horses died. 



§ 389. 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 hyperemic, swollen and sprinkled with slight 

 hemorrhages. The submucosa is yellowish in color and infil- 

 trated 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-cecal 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 

 hyperemic and swollen. In rare ca.ses, the mucosa of the 

 larynx is inflamed, also the subcutis when inflammatory swell- 

 ings appear on the skin. Schiitz found that in the brain and 

 spinal cord the arachnoid spaces are filled with a fluid which 

 is generally clear, although it may contain leucocytes. He 

 reports one case in which the lateral ventricles contained a 

 large quantity (20 c. c.) of fluid. The other lesions which 

 may be found depend upon the extent or localization of the 

 disease. Usually the spleen is slightly enlarged ; small 

 hemorrhages in the intestines, under the serous membranes 

 and in the lungs, eyes and brain ; gelatinous infiltration of the 



