DISEASES OP RESPIRATORY ORGANS 159 



EDEMA 



Pulmonary edema is not common in swine kept under ordinary 

 conditions, but it is often found in those that are hyperimmunized 

 for the production of anti-hog-cholera serum. Those having experi- 

 ence as serum producers occasionally have a swine die of pulmonary 

 edema at the time or immediately after the intravenous injection of 

 quantities of virulent blood. 



In comparison to their size, swine have a relatively small lung. 

 The virulent blood that is used in hyperimmunizing is defibrinated 

 but contains both the red and white blood cells, some of which are 

 disintegrated. Large quantities of this defibrinated blood, contain- 

 ing corpuscles in various stages of disintegration as well as the virus, 

 are introduced into an ear vein. The first capillary system it would 

 pass through is in the lung where, no doubt, more or less obstruction 

 of capillaries is effected and the virus, or some chemical ingredient 

 of the blood, may cause an increased permeability of the blood ves- 

 sels and facilitate the outpouring of the serum. 



Lesion. — The lungs are engorged with blood. The air cells con- 

 tain varying quantities of serum, the lung thus becoming soggy and 

 edematous. No other lesion of any significance is found. 



Symptoms. — The affected animal at first becomes restless and un- 

 easy. There is increased respiration, soon followed by dyspnea, 

 cessation of breathing, and death. In some eases all these symptoms 

 occur within a few minutes and during the time that the virus is 

 being introduced. If the injection is stopped instantly when the first 

 symptom becomes evident some of the affected swine will recover, 

 but in some of them the various symptoms occur, succeeded by death, 

 even th6ugh the introduction of virus be stopped when the first 

 symptom appears. An occasional case occurs where the swine will 

 show no discomfiture at the time of the injection of the virus, but 

 may be found in distress from a few minutes to an hour later. In 

 such cases, death will usually result. 



Treatment. — Thus far no treatment has been found that appears 

 to be of value. It is possible that centrifuging the virus will over- 

 come the difficulty. 



HEJIORRHAGE 



Pulmonary hemorrhage is not common in swine as a primary dis- 

 ease. It has been reported as occurring in fattened swine that are 



