VARIOLA. 437 



COW or horse. The results of numerous experiments which have been 

 carried out for the purpose of determining the reL^tionship existing 

 between variohi of the human and bovine families seem to show, 

 however, that although possessing many similar characteristics, they 

 are nevertheless distinct, and that in spite of repeated inoculations 

 from cattle to man, and vice versa, no transformation in the real 

 character of the disease ever takes place. 



Symptcxms. — The disease appears in four to seven days after 

 natural infection, or may evince itself in two or three days as the 

 result of artificial inoculation. Young milch cows are most sus- 

 ceptible to an attack, but older coavs, bulls, or young cattle are by no 

 means immune. The attack causes a slight rise in temperature, which 

 is soon followed by the appearance of reddened, inflamed areas, prin- 

 cipally upon the teats and udder, and at times on the abdominal skin 

 or the skin of the inner surface of the thighs. In a few cases the 

 fkin of the throat and jaws has been found similarly involved. If 

 the affected parts are examined on the second day after the establish- 

 ment of the inflammation numerous pale-red nodules will be found, 

 Avhich gi'adually expand until, within a few days, they reach a diam- 

 eter of one-half inch or even larger. At this period the tops of the 

 nodules become transformed into vesicles which are depressed in the 

 center and contain a pale, serous fluid. They usually reach their 

 maturity by the tenth day of the course of the disease and are then 

 the size of a bean. From this time the contents of the vesicles become 

 purulent, which requires about three days, when the typical pox 

 pustule is present, consisting of a swelling with broad, reddened base, 

 within which is an elevated, conical abscess varying from the size of 

 a pea to that of a hazlenut. 



The course of the disease after the full maturity of the pustule is 

 rapid if outside interference has not caused a premature rupture of 

 the small abscess at the apex of the swelling. The pustules gradu- 

 ally become darker colored and drier until nothing remains but a 

 thick scab, which at last falls off, leaving only a slight, whitish scar 

 behind. The total duration of the disease covers some 20 days in 

 each animal, and owing to the slow spread of the infection from 

 animal to animal, many weeks may elapse before a stable can be fully 

 freed from it. The fallen scabs and crusts may retain their conta- 

 gious properties for several days when mixed with litter and bedding 

 upon the floor of the stable, and at any time during this period they 

 are capable of producing new outbreaks should fresh cattle be brought 

 into the stalls and thus come into actual contact with them. Again, 

 the pustules may appear, one after another, on a single animal, in 

 which case the duration of the disease is materially lengthened. 



Treatment. — In herds of cattle that regularly receive careful han- 

 dling, no special treatment will be found necessary beyond the appli- 



