694 VETEEINARY HYGIENE 



disinfected with a plumber's lamp or lighted wisps of 

 straw. 



Cow-pox appears as a vesicular eruption on the udder 

 and teats, which about the eighth day passes into a pustular 

 stage. The number of eruptions on each teat and quarter 

 is generally two or three, but may in severe cases be four or 

 five. The eruption is circular or oblong in shape, with 

 either a flattened or umbilicated centre, and a slightly 

 raised, well-defined areola. The rupture of the vesicle is 

 followed by a brown crust under which healing occurs, and 

 when this falls off a depression remains surrounded by a 

 brownish tint of skin. 



The eruption is accompanied by fever and a slight diminu- 

 tion of milk-supply. Irritation from the hands of the 

 milker delays the process of healing. Infection both of 

 the milker and the remaining cows will almost certainly 

 occur ; either may be a source of infection to the other. 



The disease it will be observed is a mild affection in the 

 cow, and its chief interest lies in the fact that the lymph of 

 the vesicle gives protection against human small-pox. 



It is almost certain that it was this affection which was 

 blamed by the medical profession for producing scarlet 

 fever in man, referred to on p. 633. As no veterinary 

 opinion was called in until too late for diagnostic purposes, 

 the nature of the Hendon eruption will always remain one 

 of conjecture. 



Malcolm in describing cow-pox, refers to a spurious form 

 of the disease or varicella, the eruption of which is quite 

 distinct, the vesicles being small, superficial, acuminated, 

 and not surrounded by a tumefied areola. Further there 

 may be successive crops of vesicles, though usually the 

 disease only lasts a week or ten days. 



Varicella, like true vaccinia, is capable of transmission 

 from cow to cow by the hands of the milker. 



The question of the use of milk for human purposes 

 derived from any form of diseased udder is one entirely for 

 the consideration of the medical profession. Where the 

 actual gland substance is involved, or the milk sinus and 



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