INFECTIOUS DISEASES 313 



and rarely fatal in other cases, but with our present knowledge it 

 does not seem advisable to attempt a symptomatic classification of 

 this disease into acute and chronic types. 



Usually the first symptom noted is depression. This disease may 

 affect only a few animals in a herd or a few animals may be af- 

 fected at one time and they either die or recover and others in the 

 same herd become infected, the disease thus ultimately affecting all 

 swine on a given farm. In other instances practically all of the swine 

 show evidence of the disease at the same time. They are dull and sep- 

 arate themselves from the other swine. Appetite is diminished, al- 

 though it may not be noted by the caretaker. In some outbreaks 

 the first evidence of the disease noted is the general dullness. The 

 owners will report that a large percentage of the hogs lack activity 

 and appear dull and depressed. As the disease progresses digestive 

 derangements become more evident and are manifested by irregular 

 appetite and diarrhea. The affected individuals at this stage appear 

 unthrifty, have rough coats and arched backs. The fecal discharges 

 are quite fluid and of variable color, depending upon the feed. The 

 affected individuals become emaciated, thin and weak and may die of 

 exhaustion or they may ultimately recover. The temperature varies 

 from normal to 105 or 106 degrees F. during the active stage of the 

 disease, but in the later stages it is not unusual to record subnormal 

 temperatures. In uncomplicated cases, no pulmonary disturbances 

 are manifested. 



Course. — The course of the disease is very irregular. In some 

 cases it is of only a few days' duration, while in other instances indi- 

 vidual animals may be affected for several weeks. 



Diagnosis. — The identification of this disease requires an autopsy 

 of one or more cadavers. The characteristic lesion upon which .judg- 

 ment is based occurs in the intestine and consists of an inflammation 

 in which some of the involved tissue has become necrotic and is ad- 

 herent to the intestinal mucosa. The finding of these lesions when 

 coupled with a definite history of the outbreak and observation of the 

 leading symptoms — irregular appetite, diarrhea, dullness and varia- 

 ble temperature — is usually sufficient evidence upon which a posi- 

 tive diagnosis can be made. 



Differential cliag)iosis. — ^Although it is not difficult to make a diag- 

 nosis of infectious necrotic enteritis it will require careful considera- 

 tion to exclude other diseases or identify complications. In differen- 

 tiating infectious necrotic enteritis from other infections, it is essen- 



