96 HOG CHOLEKA 



pass, but occasionally the effect is observed in the 

 skin. Severe and general congestion, interspersed 

 with areas revealing slight or extensive hemor- 

 rhage, are the usual changes observed in the 

 lungs. 



Prevention of sudden death resulting from hy- 

 pering is not always possible. Fatalities occur 

 much less frequently if the virus used is first 

 thoroughly cooled. Even ordinary refrigerator 

 temperatures are not objectionable. As a second 

 precaution a close watch should be kept on the hog 

 during the process of hypering, though it is not 

 always possible to distinguish between struggles 

 due to fright and perversity and those due to 

 genuine distress. Real danger is marked by a 

 sudden inspiratory gasp or rapidly developing 

 dyspnea, especially when these symptoms are ac- 

 companied by violent struggling and nervous 

 symptoms such as twitching of the snout or eye- 

 lids and protrusion or shuttling of the eyeballs. 

 If distress is not severe the flow of virus may be 

 checked momentarily and then allowed to con- 

 tinue slowly, but as a rule it is best to release the 

 hog and take no further chances. Usually in sub- 

 sequent trials these hogs will tolerate hypering 

 without incident. 



Sometimes it is not until the hog is released 

 from the crate that we observe symptoms. Vomit- 

 ing occurs somewhat frequently at this time but 



