350 Foot-and-Mouth Disease. 



suitable measures, and herds, especially those on large farms, 

 may be protected from the infection. The principles for preven- 

 tion are, in general, the same as those applied to other infectious 

 diseases, and expressed briefly are, that healthy animals 

 should be protected in every possible way from coming in 

 contact with the unhealthy ones, or with those which have recov- 

 ered within a short time (see also page 334), and also from 

 coming in contact with contaminated utensils. 



A quarantine of at least two weeks duration for newly 

 introduced animals appears to give good results in this respect. 

 It is furthermore advisable, during threatening periods, espe- 

 cially in already infected herds, to prevent the calves from 

 sucking their mothers, but they should be given milk that has 

 been heated to 70 degrees. 



Emergency and protective vaccination. Emergency vaccin- 

 ation with virulent material, and immunization proper, possess 

 a marked ditference in their value and in their practical im- 

 portance. 



I. Emergency vaccination. This method, in which the dis- 

 ease is produced in healthy animals by the inoculation of 

 virulent material, is employed to shorten the disease in already 

 infected herds, when more energetic measures of eradication are 

 not adopted. 



The disease usually affects all of the susceptible animals 

 in an infected herd owing to its remarkable contagiousness, 

 but inasmuch as its transmission from animal to animal 

 occurs only successively, a long time usually elapses before the 

 last animal recovers and the entire herd may be considered 

 free from infection. In order to diminish the loss due to 

 inability of the animals to work by a more rapid passing of 

 the infection through the herd, and to reach as soon as possible 

 the removal of the quarantine period, artificial infection of all 

 animals in the herd after the appearance of the first cases, ap- 

 pears indicated. The advisability of this procedure is also sup- 

 ported by the experience that the inoculated disease usually runs 

 a milder and frequently also a more rapid course than the 

 natural infection. In order however to prevent severe losses, 

 the inoculation should be undertaken only in outbreaks in which 

 the disease is mild in character, and in which deaths in adult 

 animals have not been observed in the vicinity. (In the spring 

 of 1904 in a county in Hungary, all of 35 inoculated cattle, and 

 39 sucking calves died within 11 days.) 



Technique of Inoculations. The simplest procedure consists in rubbing or 

 superficially scarifying the mucous membrane of the mouth lightly with a clean 

 coarse piece of linen, and then applying the saliva of affected cattle; or the animals 

 are given coarse food contaminated with such saliva. The saliva should be taken 

 only from animals which have vesicles in their mouths, as the saliva is rendered 

 infectious by their contents alone, whereas it is no longer infectious when the 

 erosions are healing. Likewise very simple and certain is the method in which 

 a piece of linen is placed in the mouth of the affected animal, which is allowed 

 to chew at it for several minutes, then the well saturated cloth is introduced 



