Infectiuus Diseases of Anit/iah. 



of the Dutcli ports. Xo precise evidence lias been obtained as to the manner 

 of the introduction of the disease into Ireland from Holland, but there is little 

 doubt that the affection existed in the neighbourhood of Cork in the latter 

 part of 1840, and there is also positive evidence of the fact that it appeared in 

 the London dairies in 1842, since which time it has never been absent from 

 some districts of this kingdom. 



Owing to the fatality which attends the progi'ess of the disease, scientific 

 and practical men have devoted a considerable amount of attention to the 

 investigation of its causes, nature, methods of cure, and means of prevention. 

 Several scientific commissions have been established in Germany, France, 

 Belgium, Holland, and also in our own country ; but it unfortunately happens, 

 notwithstanding the investigations which have been carried out, that some 

 of the most important points in connexion with, the malady still remain 

 undetermined. 



For some time after the appearance of limg disease in this country a differ- 

 ence of opinion prevailed among scientific and practical men as to its con- 

 tagious character. It is now, however, admitted that pleuro-pnemnonia is a 

 contagious disease. The experiments which have been made, however, do not 

 satisfactorilj' determine the manner of the communication of the disease. It is 

 certain that the introduction of a diseased animal into a healthy herd will, in 

 the majority of instances, be followed by the extension of the disease to a 

 curtain per-centage of the healthy animals. But it is remarkable, on the other 

 hand, that all attempts which have been made to communicate the disease bj' 

 the matter obtained from the lungs have invariably failed, at least in this 

 country. 



It is asserted by Yix that pleuro-pneumouia followed the introduction of a 

 portion of diseased lung under the skin of the dew-lap of a bull, and another 

 l^ortion, after being washed in cold water, placed in the same position in a cow 

 produced the same effect. In both these cases, however, only six days elapsed 

 before the symptoms of pleuro-pneumonia presented themselves — a fact which 

 goes far to prove that the animals were the subjects of the disease at the time 

 of the inoculation. 



Introduction of the fluid exuded from a diseased lung produces local symp- 

 toms, which have been asserted to resemble those which are presented by the 

 lungs of the animals which have taken the disease naturally. Frequent 

 examination of such cases has convinced me that the exudation which takes 

 place into the areolar tissue is identical in character with that which is obtained 

 from the lungs ; but in no instance has it been found that constitutional 

 symptoms of the disease follow inoculation, and in no case has it occurred that 

 disease of the lungs has been produced by introduction of the morbid matter 

 into any part of the animal's body. 



In the majority of cases considerable swelling of the inoculated parts occurs 

 after the expiration of a week to a fortnight. But during this period no rise of 

 temperature has been remarked, nor has there been any indication of febrile 

 disturbance except in those instances in which severe local inflammation has 

 occurred, followed by mortification, and finally loss of the tail. 



Professor Baldwin, of Glasnevin, states that he has succeeded in producing 

 pleuro-pneumonia by the introduction into a healthy animal's nostrils of a 

 little cotton wool which had previously been placed in the nostrils of a diseased 

 ■beast. The same experiment has been performed in this country recently 

 without any injurious consequences to the animal experimented upon ; the 

 lungs taken from a diseased animal have also been placed in a shed in which a 

 healthy heifer was kept, but failed to communicate the disease to her. 



So far as our observations enable us to decide, pleuro-pneumonia can only 

 be communicated by actual contact of a diseased animal with a healthy one ; 

 and it is, at least, exceedingly probable that the mode of communication is by 

 the inhalation of the breath of the diseased subject. 



