234 CATTLE DISEASE. 



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times impossible, to fix with any accuracy the date of the attack. 

 Deceptive, in that, in animals which have had the disease and may 

 be fairly presumed from appearances, to have recovered, one or 

 both lungs have been found, on slaughtering them, to be little else 

 than a mass of disease. 



That it is both malignant and fatal unhappily needs no proof 

 Nearly one thousand animals have already fallen victims, either to 

 the disease, or to the efforts made with a view to its extirpation ; 

 and more than an additional thousand are either known to be sick, 

 or from having been exposed are under the ban of suspicion. It is 

 not true that the distemper is universally fatal, for not a few sur- 

 vive which have been its subjects ; but it is not yet positively 

 known that even one has been absolutely cured. They often come 

 to eat well, drink well, and thrive tolerably ; thus exhibiting the 

 ordinary characteristics of health, and yet, a post mortem examin- 

 ation has, within our own observation, shown how utterly falla- 

 cious were all these indications in such a case. 



Regarding the term of incubation, and of propagation, or the 

 length of time which elapses between exposure and the appearance 

 of disease ; and also during what period the animal is capable of 

 conveying the disease to others, we greatly regret our 'inability to 

 arrive at definite or satisfactory conclusions. In some cases the 

 disease is apparent within ten days after exposure ; in others, 

 twenty, thirty, sixty, ninety days or even more, are supposed to 

 elapse. One case is reported where the exposure was seven months 

 previous. The more usual period appears to be not far from twenty 

 days. When the capability of the animal to convey disease to 

 others begins or ends, we have no knowledge. This is a most im- 

 portant point, but all we know is, that it may and does do so before 

 any symptoms of illness appear ; and, as the lungs of some which 

 have been slaughtered exhibit evidence of the later stages of the 

 disease in one portion and of the earlier in another, there seems 

 reason to fear that the term may sometimes be indefinitely pro- 

 longed. 



As already remarked, this lung murrain, or by whatever other 

 name it be called, is of the most insidious nature. Any disturbance 

 of the animal's health is rarely noticed until the disease is fully 

 established, and effusion into the chest has made some progress. 

 The ordinary rule, that not much ails an animal until it refuses to 

 eat, does not hold good with this disease. The early symptoms 

 are so faint and obscure as to excite neither anxiety nor attention. 



