BUREAU OF ANIMAL INDUSTRY. 



225 



tie had for a long time been quarantined at the sea-board a sufficient 

 time to make it impossible that this disease could have been carried by 

 them to the West. It was absolutely impossible to find any satisfac- 

 tory manner by which a foreign contagion could have been introduced. 



This important indication seems to have been greatly neglected in 

 deciding upon the nature of the disease in Kansas. It was said if this 

 is foot-and-mouth disease we must acknowledge that we have it, whether 

 we can trace its introduction or not. Plausible as this reasoning may 

 seem we must admit that it is not always an easy matter to diagnose a 

 disease off-hand from its superficial characters. And in the diagnosis 

 of contagious diseases we must remember that the symptoms are but 

 the* expression of the effects of the virus, and that these symptoms 

 mav be simulated more or less closely by other agencies acting upon 

 the* animal economy. . ♦ 



The history of the origin of any disease believed to be contagious is, 

 then, a most important part of the evidence to be taken into considera- 

 tion before a diagnosis is reached. . We may take contagious pleuro- 

 pneumonia for example. Many cases of this disease resemble so closely 

 spontaneous inflammations of the respiratory organs in cattle that it is 

 absolutely necessary before a diagnosis can be reached to inquire if the 

 contagious pleuro-pneumonia has been introduced or if the malady occur- 

 red spontaneously. The same principle holds good to a greater or less 

 extent with other diseases, and it may be safely asserted that when the 

 history does not receive proper consideration many mistakes will be 

 made that otherwise might be avoided. 



Contagiousness. — Thevirus of foot-and-mouth disease is one of the most 

 active contagions known. The period which elapses between exposure 

 and the appearance of the first symptoms of the disease is, as a rule, 

 bat two or three days; a very large proportion of exposed animals be- 

 come diseased, and the plague spreads rapidly from farm to farm. As 

 a result of these characters, within a week after the introduction of 

 foot-and-mouth disease into, a herd nearly every animal in that herd 

 shows unmistakable evidences of having contracted it. A very small 

 proportion of the animals may resist the contagion, but this proportion 

 is much less than with most other contagious diseases, and is so small 

 that it does not affect the rule just mentioned. 



The disease at Neosho Falls showed very different characters from 

 this. Goodrich's herd suffered in the largest proportion, 65 out of 90, 

 or 68 per cent., being more or less affected. The first case here 

 occurred January 10, and no others until February 15, or more than 

 a month later. After this new cases continued to develop for two or 

 three weeks. But in a lot adjoining that in which the sick cattle 

 were placed there were 20 calves, which remained entirely free from 

 disease. The isolation of these calves was not sufficient to hold foot- 

 and-mouth disease in check for a single day; it was even said that the 

 sick cattle had been driven through the calf lot to water, and that some 

 .of the smaller ones, when attacked, were placed with the calves. 



At Keith's 74 out of a total of 118, or 63 percent, were affected. 

 At the end of the first week but 20 or 30 head had been attacked, and 

 from this time new cases continued to appear until March, or during 

 a period of two months. Here also it is to be remembered that in a 

 lot of animals separated from the sick ones by a simple rail fence 

 there was no appearance of disease until two months after it had at- 

 tacked the first lot. Hogs were running in the lot with the worst cattle; 

 they even ate the blood of the slaughtered ones and nibbled at the 

 affected feet, but they did not suffer in the least. A sow had brought 

 15 a— '84 



