68 HOG CHOLERA 



date of injection the pig should be protected from 

 extraneous hog cholera infection; all receptacles 

 and instruments used in making the injections 

 should be sterilized. 



5. Symptoms of hog cholera should appear in 

 less than eight days following the injection. 



6. The pig should die in less than seven days 

 following the appearance of symptoms, or at the 

 end of that time, providing it is still sick, it should 

 be killed. 



7. Autopsy should reveal typical hog cholera 

 lesions in at least two organs. 



8. In negative experiments the susceptibility of 

 the experimental pig should be proved by a subse- 

 quent injection with at least 1 mil of virulent hog 

 cholera blood. 



Differential Diagnosis 



Peculiar difficulties are met in the differential 

 diagnosis. Clinical examination of the individ- 

 ual is subject to limitations which are not encoun- 

 tered in dealing with larger animals, and some of 

 the maladies which we seek to differentiate from 

 hog cholera occur so frequently in combination 

 with that disease that we do not always have well 

 defined features upon which to base our conclu- 

 sions. Thus under certain circumstances we have 

 not only to decide whether a given outbreak is 

 hog cholera or swine plague, but we must also 



