REPORT OF THE BUREAU OF ANIMAL INDUSTRY. 79 



BRIEF SUMMARY OF THE IMPORTANT FEATURES OF THIS EPIZOOTIC. 



The high, percentage of mortality in epizootics of hog cholera like 

 the foregoing is the first thing to claim our attention. Out of 119 

 animals not less than 100 perished in the brief space of two months, or 

 over 80 per cent. As no disinfection was resorted to, and no isolation 

 of the healthy attempted, it is difficult to say what number could 

 have been saved. At any rate the above figures indicate the mor- 

 tality of this disease when left to itself, and it shows that nearly all 

 young animals, such as weigh between 50 and 100 pounds, are sus- 

 ceptible to this disease. 



Most of the animals died rather unexpectedly. Only a compara- 

 tively small number were visibly diseased some time before death. 

 Since in many there was more or less ulceration in the large intestine, 

 it indicates that animals may be in a very bad condition and become 

 a source of infection for others without showing it. 



The swill feeding has already been mentioned as a probable cause 

 of the cirrhosis of the liver observed in so many of these animals. 

 This organ was tough and imparted a gritty sensation to the hand 

 when cut. The parenchyma was softened and degenerated. It seems 

 reasonable to suppose that this chronic malady may have made the 

 herd far more susceptible to the disease, and more especially -to the 

 acute hemorrhagic type. 



Hemorrhagic lesions. At least one-third of the cases examined 

 showed lesions of a hemorrhagic character. The most common 

 was an infiltration of the cortical portion of lymphatic glands with 

 blood; sometimes the entire gland appeared hemorrhagic on section. 

 As regards the relative frequency of this condition, the bronchial, 

 posterior mediastinal (aortic), and inguinal glands stand first; next 

 the retro-peritoneal, meso-colic glands, and those in the lesser curva- 

 ture of the stomacn. The mesenteric glands were rarely affected. 

 Accompanying this condition of the lymphatics is usually a very 

 large spleen, its great size being simply due to an engorgement with 

 blood. 



Next in frequency were the hemorrhagic lesions of serous mem- 

 branes in the form of punctiform extravasations, larger ecchymoses, 

 and very rarely of collections of blood infiltrating the muscular lay- 

 ers beneath the serous membrane. These extravasations are most 

 frequent on the auricles and ventricles of the heart, under the serosa 

 of the large and small intestines, beneath the pulmonary pleura, and 

 in the subcutaneous tissue. In the severest cases blotches appeared 

 on the diaphragm and costal pleura. In about 10 per cent, the 

 kidneys were hemorrhagic. Usually the glorneruli appear as minute 

 blood-red points. To this may be added hemorrhages in the pyra- 

 mids and extravasations collecting around the papillae. 



The mucous membrane of the stomach in hemorrhagic cases is, as 

 a rule, deeply reddened in the fuiidus, or else there is hemorrhage 

 into the membrane, more rarely on the surface. The mucosa of the 

 small intestine is usually intact, but that of the large intestine in the 

 acute form of the disease is in the same condition as the stomach. 

 In older cases, when not covered with ulcers, it is either pigmented 

 or dark red, chronically congested. This o'ubbreak was characterized 

 by hemorrhagic lesions more than any other which we have exam- 

 ined. Our experience has been that the early cases are hemorrhagic 

 and are succeeded by those in which ulcerat'ion, cellular infiltration 

 of the lymphatics, and marantic conditions, such as serous effusions, 



