170 THE DISEASES AND DISORDEES OP THE OX. 



respiratory organs. The name pleuro-pneumonia indicates that 

 changes* of an inflammatory character are found both in the 

 pleurse (the lining membranes of the lungs, and of the chest 

 cavity) and in the lungs themselves. There is also an effusion 

 of lymph into the pleural sacs. Usually the bronchi become 

 more or less stopped up. The inflammatory process spreads 

 along the lymphatics. Acute pleurisy, with high fever and 

 various functional derangements, may occur. The disease is of 

 a highly contagious nature. Bovine animals only seem to be 

 attacked, though it has been said to extend to the deer, and 

 some think it is allied to some forms of acute croupous pneu- 

 monia of the human subject. It is allied to the general specific 

 diseases, and one attack apparently confers immunity. 



Causes. — We may naturally suppose that there are usually 

 certain conditions which, while aiding in the development of the 

 disease, do not actually cause it. They are the following : — Toa 

 much food, improper or sudden changes in the food, prolonged 

 feeding on the residues of distilleries and breweries ; excessive 

 milking, hot or damp byres, marshy and badly-drained pastures, 

 cold, damp, bad water, faulty sanitation. In short, all those 

 conditions which will damage a healthy animal, will, it is 

 thought, render it liable to the attacks of this disease, if the 

 specific virus is at hand even in small quantities. The trafiQc in 

 diseased cattle adequately supplies this virus, and thus accounts 

 for the diffusion of the disease. It is thought that severe 

 weather, bad feeding, and all conditions of an injurious nature 

 cause a greater susceptibility to the ravages of this disease, but 

 that they do not bring about its spontaneous origin. 



As yet we have not very accurate information as to the germs 

 of this disease. It is said by T. Poels and Dr. W. Nolen that 

 the micrococci of pleuro-pneumonia of cattle have been success- 

 fully cultivated, and that the pulmonary exudations contain 

 micrococci identical in form and mode of growth with those 

 found in human pneumonia. These observers also make the 

 important assertion that cultivated micrococci, derived either 

 from human pneumonia or from pleuro-pneumonia of cattle^ 

 produce in cattle typical pleuro-pneumonia. Dr. Klein, from 

 his own observations, feels disposed to doubt the accuracy of 

 these statements. At any rate, it may be regarded as established 

 that contagious pleuro-pneumonia is generated by, and due to,. 



