SHEEP POX 47? 
mm. in diameter appear on the second or third day. These change in 
from 1 to 2 days into somewhat larger vesicles filled with a clear 
lymph. The vesicles are reddish or bluish or yellowish white with a 
mother of pearl or metallic lustre, depending upon the thickness of 
the skin and its color. On the body of the udder the vesicles are 
uniformly round while on the teats they are oval, surrounded by a red 
zone of 1to 2mm. in width. From the 8th to the 11th day they show 
a well defined depression. This may be absent. Following this, the 
contents of the vesicles become purulent, dry up and form scabs. 
After the scabs drop off the underlying skin is reddened and slightly 
swollen but later shallow cicatricial depressions are formed. Usually 
there are but few vesicles, 15 to 20, and they do not all appear at the 
same time but at intervals of a few days between the first and last. 
Sometimes two weeks may elapse before the development of all of the 
vesicles. Rarely a parenchymatous mastitis may be associated with 
the skin lesions. Usually the eruptions are restricted to the udder 
and teats. When cow pox is transmitted to the horse it is said to be 
liable to produce generalized eruptions. Milk from infected cows is 
liable to be contaminated from the pustules and capable of transmit- 
ting the disease. Milkers of infected cows are liable to be infected 
unless they have been previously vaccinated. 
Diagnosis. The diagnosis of cow pox is to be made on the presence 
of the roundish or oval vesicles containing a depression in the center 
and the spreading of the eruption to other animals. It is to be differ- 
entiated from foot-and-mouth disease and from other eruptions of 
the skin. These have been grouped under the name of “false cow 
pox” by Ceely and Hering. Gamgee described varicella or chicken 
pox as occurring in cows. 
Immunization. Efforts have been made to immunize cattle against 
this disease by vaccinating them with,calf lymph used for man against 
small pox. The results are not uniformly successful. 
SHEEP POX 
Synonyms: Variola ovina; clavelée; Schaf-pocke. 
Characterization. Sheep pox is an acute exanthematous disease 
peculiar to sheep, characterized by a typical variolous eruption on 
those parts of the body either devoid of wool or scantily covered with it. 
History. Sheep pox is supposed to have been introduced from 
Central Asia. It was extensively studied by Joubert and Rabelais 
