THE LUNG PLAGUE. ' 69 



than one per cent, by death, and nnder five per cent, of the tails have 

 lost their tips. This incUides m^^ earlier trials, and the results wonld be 

 more favorable if I exclnded them from my calcnlations. 



PRECAUTIONS. 



The prevention of pleuropneumonia by inoculation demands, therefore, 

 sjiecial attention, first, to the condition of herds operated on ; second, selec- 

 tion of proper virus; third, the preservation of that virus from de(;om- 

 positionj fourth, the proper performance of the operation. 



First. As to the condition of stock, it may be said that at any season 

 and under any system of management, whether cattle are being grazed, 

 stall-fed, used for breeding purposes, or fattening for the butcher's stall, 

 inoculation may be resorted to. It should be practiced so soon as there 

 is reason to believe a herd has been in danger of infection or actually 

 infected. Tlie first case of well-marked lung plague on a farm or in a 

 dairy shed should be the starting point for careful isolation, and the 

 inoculation of all apparently healthy animals. The disease rarely mani- 

 fests all its virulence until the third month after the introduction of a sick 

 animal among a lot of cattle, but the longer the inoculation is delayed 

 the more likely is it that the operation will be performed on animals 

 during the stage of invasion of the natural disease, and the result is a 

 loss which is sometimes ascribed to the ineflficacy of the preventive. 

 In cities where the lung j>lague has been rife for any length of time, and 

 it is "necessary to make frequent purchases, although a great deal in the 

 way of prevention may be eflected bj^ judicious purchases of animals in 

 healthy districts, it is best to resort regularly to inoculation. Dairymen 

 should strive to buy more cows at a time, and at regular intervals, instead 

 of i^icking up a chance bargain or making it a rule to go to the market 

 weekly, as has been often the custom in both England and America. It 

 matters not if the cow is about to calve or has just calved ; nothing should 

 induce the dairyman or the farmer in an infected district to run a risk. 

 It is desirable to keep animals clean and well littered on straw or saw- 

 dust, as at times the tails that have been operated on are permanently 

 in excrement and urine, which may poison the wound with decomposing 

 matter. 



Second. The selection of proper virus is a matter that should be 

 intrusted to veterinarians, who can detect the various stages of the dis- 

 ease. It is during the first stage of a mild case that the interlobular 

 tissue of the lung is found disteuded with a yellow gelatinous serum, 

 w^hich is fluid so long as the lungs are hot, and is not readily contami- 

 nated by other inflammatory products and blood. When a large portion 

 of luug has been so far cf)usoli(liit('(l as to present an abaost uuiforin dark 

 red or purplish color, it should be discarded, and especially in cases wheiv 

 a piece of the organ has become gangrcMious and detached, or where licpiid 

 in the cavity of the chest and around the lungs is decidedly fetid. IMicro- 

 scopic examination will iudicate, by the presence of movable rods and 

 floating molecules, the putrefactive changes, and that should cause us to 



