CONTAGIOUS LUNG FEVEK OF CATTLE. 229 



having already reached the latter State ; an occuiTence -which was inevitablo soonci 

 or later, but the actual existence of which must enormously increase our dangers. 

 With every suck step westward there is the introduction of more diseased and infected 

 cattle into the natural current of the tratlic, and the earlier probability of the general 

 infection of all parts to the east of such ultimate centers of disease. There is, further, 

 the infection of more cattle cars, which, can-ied West, may be the means of seciu-ing a 

 rapid extension of the ijlaguo to our most distant States and Territories. 



EELAXm^ DANGERS OP THE POISOXS OF LUXG FEVER jV>'D OTHER PLAGUES. 



The persistent vitality of the Inng-f ever poison, in comparison with that of any other 

 animal plagues, is noteworthy. It has held a tenacious grasp on the United States 

 for over a third of a century, though forbidden by circumstances to make a wide ex- 

 tension. Aphthous fever (foot and mouth disease), on the other hand, though twice 

 imj)orted into Canada within the last ten years, and on one occasion widely spread in 

 New York and New England, was on each occasion easily and early extinguished, and 

 with little or no effort on the i^art of the States. It might indeed almost bo said to 

 have died out of itself. Even the dreaded rinderpest has its poison early destroyed by 

 free exposure to the au-, in thin layers, at the ordinary summer temperature. Numer- 

 ous experiments on hides hung up and freely exposed in warm weather have shown 

 that the infecting power is lost as soon as they are quite dried. But the poison of 

 lung fever maintains its virulence for months in the dry state in buildings, and we 

 have known parks, with sheds, that proved regularly infecting year after year to all 

 cattle turned into them. In other eases we have known the virus carried for miles on 

 the clothes of attendants, and thus introduced into new herds. 



A far greater danger hea in the lengthened period during which the poison of lung 

 fever remains dormant in the system. This averages about three weeks or a month, 

 but may extend, in exceptional cases, to not less than two months. An ox or a cow 

 which has been exijosed to the contagion may, therefore, be carried from one extremity 

 of the continent to the other, may he exposed in a succession of markets, and may 

 change hands an indefinite number of times, and bo all the while in the best apparent 

 health, though infallibly approaching the manifestation of the disease, and for the 

 latter portion of the time spreading the germs of the malady to others. There is here 

 an opportunity for the unscrupulous to sell otf exposed and infected animals without 

 the i)urchaser having the least suspicion of foul play. There is also the strong proba- 

 bility of animals that have contracted the disease by accident, in cars or otherwise, in 

 passing to a new home, mingling with the herd of the new owner and infecting them 

 extensively before there is a suspicion that anything is amiss. This long period of 

 incubation after the animal is infected, and the equally long period of latency of the 

 malady in animals he has infected, one or two of which only will bo attacked at inter- 

 vals of a month, lull suspicion as to the ])resence of contagion, and it is too often only 

 after great damage has been done that the truth dawns on the mind. 



In aphthous fever and rinderpest, on the other hand, the disease shows itself in 

 from one to four days after infection, and the surrounding animals .are so rapidly at- 

 tacked after the coming of the infected stranger, that there is no room for hesitancy 

 as to the existence of contagion. Nor can the victims of these diseases be carried far 

 from the point where they have been infected and disposed of as sound animals ; so 

 that in the very vigor and promptitude of their action we have an excellent basis for 

 their restriction and control. 



DANGER OP INFECTION IN OUR UNFENCED STOCK R.VNGES. 



It is needful to note the above-named insidious progress and stealthy invasions of 

 the lung fever, and to contrast them with the more prompt and open manifestations of 

 the other animal plagues, in order to show the great peril to which we are subjected 

 by the presence in our midst of ii pestilence which literally iraJketh in darkness. Let us 

 now consider the prosiiective infection of our great stock ranges. That this is inevi- 

 table, though slow, at the present rate of progress of the plague, has been sufficiently 

 shown. That it might occur aiiy day by an animal infected in an Eastern farm or 

 stock-yard, or in a railroad car in which it was sent for the improvement of the West- 

 ern herds, nuist be al)undantly evident lo every one who has read this article. If wo 

 now add tho fact that more than one thorouf/hhred Jyrshire and zrcrseji \iQvd has been 

 infected with this disease during the ])ast year^ wo are at once confronted with a strong 

 probability of an early Western infection. Let us rcmcuiber that thoroughbreds alone 

 are carried West for improvement of native h<T(ls, and that a bull of the Ayrshire, 

 Jersey, Holstein, or short-horn breed, taken from a herd now or recently infected, may 

 be carried to any of our Western Territories and miughi for .a month with the native 

 herds before his own infection is so nnich as suspected, and wo can conceive how im- 

 ■jainent is the danger when the infection has reached our Eastern thoroughbred cattle. 



To iUustrate tho result of tho infection of our unfeuced stock ranges, I must quote 



