CHAP. I. PLEURO-PNEUMONIA. 547 



been vexatious and abortive. Since, however, the adoption of a rational 

 system of sanitary police, the disease has become exterminated. 1 



Pleuro-pneumonia is believed to be due to an almost invisible 

 organism, 2 which enters the body of its victim through the breathing 

 organs and acts directly upon the lungs. To be effectual it requires that 

 healthy animals shall be brought into contact or near proximity with the 

 sick, so that the virus may pass directly from one to the other. As the 

 contagion quickly perishes after leaving the lungs of the patient, the 

 spread of the disease by straw, hay, manure, and other means such as 

 ordinarily carry it is rendered abortive. 



The period of "incubation is not a fixed one, but varies in different 

 cases between three weeks and probably as many months. As a rule 

 the shorter term may be accepted. 



Symptoms. The symptoms of the disease vary in intensity according 

 to the severity of the attack. In some instances they are very trifling 

 and do not amount to more than slight rise of temperature, unthrifty 

 appearance of the coat, shivering, with impaired appetite, and in milch 

 cows some diminution in the secretion of milk. In the more severe 

 cases these signs of ill health are aggravated, and in addition the 

 breathing becomes more frequent than normal, and ultimately hurried 

 and difficult. The animal coughs at first, only now and then, but as 

 the lungs become more and more involved, this symptom is frequently 

 repeated. In severe cases a deep grunt accompanies the breathing with 

 each expiration, and may be provoked by movement, or by pressing 

 the side of the chest in the space between the ribs. If the ear be 

 applied to the affected side a rubbing sound may be heard. The pulse 

 is quick, full, and at first firm to the touch, but afterwards becomes small 

 and weak. The appetite falls away. At first the bowels are constipated, 

 but this gives way to diarrhoea, with foul-smelling evacuationa 



The animal now stands with the head poked out, the mouth wide 

 open and the tongue protruded. The respiration becomes laboured 

 and gasping, and the patient succumbs to suffocation and a vitiated 

 condition of the blood, which the spoilt lungs have failed to purify and 

 correct. Notwithstanding our familiarity with the symptoms exhibited 

 in this disease, it is seldom that even the most expert veterinarian is 

 able to positively assert its existence without a post-mortem examina- 

 tion. Pleuro-pneumonia arising from cold and other accidental causes, 

 some forms of heart disease, tuberculosis, and parasitic affections of 

 the lungs all occasion similar manifestations. The rate of mortality 

 in this disease is very considerable, but recent experience has shown 

 that many cases recover from it. When this occurs a portion of the 

 diseased lung is usually destroyed, and from it infection may be 

 given out for months, though the animal itself appears healthy. 



Treatment. The lawprovides that all animals affected with the disease, 

 and such others as have been in contact with them, shall be destroyed. 



1 Up to the spring of 1908 no outbreak of pleuro-pneumonia had occurred in Great Britain 

 since January 1898, or in Ireland since September 1892. 



2 See ' ' The Microbe of Pleuro-Pneumonia," by Professor M'Fadyean. Journal of the Royal 

 Agricultural Society, 3rd series, vol. ix., 1898, p. 388. 



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