Cholera Suis, Hog Cholera, etc. 51 ' 



and congested, though the discoloration may be largely confined 

 to the cortical layer. The spleen is as a rule normal in size. The 

 liver is firm, but it may show softening of the secreting acini and 

 encrease of the fibrous framework. Petechise or circumscribed 

 haemorrhages may or may not be present on or under the serosas 

 or in the tissues. 



The characteristic lesions belong to the gastric-intestinal organs. 

 Congestions and ulcers may be found on the gastric mucosa, on 

 that of the small intestine, and rectum, but they are above all com- 

 mon on the ileocsecal valve, caecum and first half of the colon. In 

 the earlier stages of these lesions mucosa and submucosa are the 

 seat of a congestion and exudation, but later the round button- 

 like ulcer usually stands out prominently with its necrotic centre 

 dirty-white, brown or black, and composed of superposed layers, 

 the whole resting on a congested and thickened submucosa. 

 This contains small round and giant cells and may show consider- 

 able encrease in connective tissue. The ulcers may be seated on 

 the agminated or solitary glands but do not show the same pre- 

 dilection for these parts which is seen in typhoid fever. 



Incubation. This varies, according to the dose and suscepti- 

 bility, from two or three to as many as thirty days. With the 

 short incubation the disease tends to assume its most acute and 

 deadly type, while the prolonged incubation bespeaks a milder 

 form. During ordinary outbreaks from six to fourteen days 

 represent the average interval between exposure and the onset of 

 active symptoms. During the extreme heats of summer and the 

 excessive cold of midwinter in our northern states incubation 

 tends to be shortened. 



Symptoms in Fulminant Type. In violent outbreaks some pigs 

 are found dead without observed preliminary symptoms, and have 

 been set down as fulminant examples of the disease. When these 

 occur during very hot weather, in open yards or fields, there is 

 reason to believe that insolation, acting on a system rendered 

 specially susceptible by the toxic fever, has much to do with the 

 early death. Though seldom observed during life, it has been 

 said that such cases, show extreme dulness, prostration, stupor, 

 weakness, unsteady gait, thirst, hyperthermia, persistent recum- 

 bency, and at times red blotching of the skin and even convulsions. 



Symptoms in Acute Type. In contrast with erysipelas these may 

 advance slowly and insidiously, there is a lack of the customary life 

 and vivacity, the tail droops, appetite is impaired, the pig creeps 



