SWINE FEVER. 711 



a very few hours after these premonitory symptoms have set in the 

 j)igs become rapidly worse; they may or may not have a deep-red 

 blush on the skin, which is more particularly noticeable on those 

 parts of the body where there is an absence of hair, such as the 

 inside of the thighs, the point of the axilla, and over the abdomen, 

 Choleraic evacuations, having a most offensive odour, succeeding 

 upon constipation, follow later on, and the animals die perhaps as 

 early as the third or fourth day after the symptoms have first been 

 observed. 



In some instances the disease proceeds with great rapidity 

 through a herd, the symptoms being of a most aggravated and pro- 

 nounced character, and the outbreak attended with great fatality. 



Generally speaking, the above description depicts the symptoms 

 of swine fever in the acute form, more especially when it breaks 

 out in a herd of young pigs. 



In the non-acute form the disease progresses slowly, the clinical 

 evidence is extremely obscure, the reddening of the skin, formerly 

 regarded as being invariably present in swine fever, is absent, and 

 beyond the fact that the animal is unthrifty, develops slowly, and 

 perhaps has a constantly relaxed condition of the bowels, it may be 

 asserted that there are no symptoms which could be regarded as 

 absolutely indicative of swine fever, and nothing short of a post- 

 mortem examination will enable even an expert to satisfy himself 

 that the animal was affected with the disease. 



As a general rule swine fever assumes this non-acute and slowly 

 progressive form in pigs which have arrived at an age when their 

 powers of resistance to disease are materially increased, i.e.. in 

 animals of eight or more months old ; on post-mortem examination 

 they are found to have been extensively diseased, more particularly 

 in the large intestine, a portion of the digestive apparatus which 

 does not appear to perform any very important function in con- 

 nection with the nutrition of the animal, and so long as the stomach 

 and small intestines remain healthy, pigs with a considerable amount 

 of disease in the large intestine may still keep up their condition 

 for a considerable time. 



Etiology. As regards the etiology of the form of swine fever 

 prevalent in England no question now exists. It has been proved to 

 demonstration by the bacteriological inquiry conducted by Professor 

 McFadyean that it is due to a special pathogenic organism, a bacillus, 

 which, after cultivation in artificial media, will produce in the healthy 

 pig fed with the pure cultures the typical ulcerations which are 

 found in the intestines of pigs affected with swine fever contracted 

 in the ordinary way. 



