DISEASES OF THE OX AND SHEEP. 307 



pysemia sets in, the febrile symptoms become very strongly 

 marked. 



Having now considered variola generally, we proceed to deal 

 firstly with bovine variola, or vaccinia, and then with vaccination. 



Bovine Variola, or Cow-pox, or Vaccinia. 



This contagious disease probably affects cattle in every part 

 of the earth, and has prevailed in the form of epidemics in every 

 country of Europe. Its power of protecting mankind from 

 small-pox has been known for a long time. In hot countries, 

 such as India, the pustular eruption, which is generally limited 

 to the udder, may be more or less general over the body. 

 Animals kept in stables appear to be more generally attacked 

 than those which are out at pasture. Probably this arises from 

 the greater liability of contact. The disease seems to be more 

 frequent in spring than at other seasons. After calving, when 

 the mammary gland has an increased supply of blood, the cow 

 apparently has a greater liability to the malady. In the general 

 way cows alone appear to be affected. Probably the disease 

 occurs in male oxen ; but is not so likely to be noticed in them 

 in consequence of the absence of the udder, an organ to which, 

 owing to cows being used for milking purposes, much attention 

 is necessarily directed. 



If cow-pox arises, as some have thought, from human small- 

 pox, it is not difficult to see the reason for this. Whether cow- 

 pox may arise independently of other animals and man or not, 

 at any rate it seems to be established beyond doubt that they 

 may get it from the direct contact of the hands of a milker who 

 is suffering from small-pox. Male oxen are susceptible to the 

 disease by inoculation. Moreover, the disease may arise by 

 means of the virus of horse-pox conveyed by attendants, and 

 probably, also, by association with horses in stables and pastures. 

 At least, this is said to be the case ; but we may point out that 

 a great deal of investigation is needed before such points as these 

 can be considered to be cleared up. 



The rash of cow-pox, as we have said, chiefly affects the 

 udders and teats of cows, being manifested by the development 

 of small, pale-red hard nodules or pustules, which vary in size 

 from that of a pea to that of a haricot bean. These pass 

 through stages altogether similar to those which characterise 



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