322 Seventeenth Annual Report of the 



Lesions in the mouth are by no means uncommon, affecting an 

 entire herd, or two herds adjacent, which might have been sup- 

 posed to have come from an earlier attack of aphthous fever, and 

 in the midst of an aggressive campaign against this disease such 

 a suspected herd which was native to the place or long resident 

 there might be disposed of in the general slaughter, and paid for, 

 without serious damage being done; but if such herd is just from 

 a reputedly sound state, the consequences of slaughter are too 

 heavy and too far reaching, to permit of condemnation until we 

 have found the fullest and most undoubted evidence of the plague. 



Abandoning compulsory slaughter increases the amount of 

 local infecting material. This in a nutshell gives the one sub- 

 stantial reason and excuse for compulsory slaughter. If an ox 

 has been 2 or 3 days in reaching the stage in which the local 

 lesions (blisters) are developed, and when the disease will be 

 recognized, it will be 3 more days ere it completes the acute 

 stage and merges into the succeeding one when the driveling of 

 infectious saliva is checked, and the separating strips of skin 

 and the contents of the blisters no longer escape. There follows 

 a stage of healing during which the shedding of the remaining 

 infected cells of the lining membrane of the mouth, and the skin 

 of the teats and feet is carried on, the margins of the hoofs, 

 where skin and horn merge into each other, being the last to com- 

 plete the process and requiring several weeks to acconrplish it. 

 Hence, the lesions of the feet communicate infection longer than 

 those of other parts, and the roads traversed, stalls, loading banks, 

 etc., and manure are especially dangerous. The conditions are 

 comparable to the desquamation of scurf in scarlet fever of man, 

 infection being scattered so long as such scurf is thrown off. 



The increased production of infection is in ratio to the time 

 during which there is active secretion and escape of the infecting 

 liquids, and, later, the shedding of the infecting cells. If there 

 were one day of fever without eruption, a second day in which 

 the eruption forms, and two days more before the rupture of the 

 majority of the vesicles, marking the height of this disease and 

 the probable date of inspection, we have to accept four days' 

 active formation of infection as already passed, and all surround- 

 ings as under the gravest suspicion. From the date of the rup- 



