SHEEP POX 479 
These are followed in from 1 to 2 days by the appearance of round red 
spots upon the skin which in some places may be surrounded by 
moderate serous infiltration manifested by an urticaria-like elevation. 
With the development of the eruption, there are more or less severe 
general symptoms. Frequently atypical symptoms and _ vesicles 
occur. At times the eruptions do not develop into vesicles. Hoare 
divides the symptoms into the discrete, regular or benign; the con- 
fluent, irregular or malignant; and variola hemorrhagica. 
In addition to the somewhat characteristic skin eruptions there is 
frequently hemorrhagic inflammation of the air passages and gastro- 
intestinal canal. Vesicles sometimes appear on the mucous mem- 
brane of the pharynx and trachea. Changes suggestive of pyemia or 
bacteriemia may be found. Occasionally there are large hard nodules 
under the skin giving a homogeneous appearance upon section. 
The duration of the disease is from 3 to 4 weeks. The mortality 
varies from about 7% in the discrete form to 20 or 30% in the malig- 
nant. Occasionally the mortality is much higher than this. 
Morbid anatomy. The vesicles attain to a size of from 5 to 
10 mm. A tenacious fluid oozes from the surface of these nodules. 
The superficial layers are split and the space filled with a 
serous fluid which develops into a bluish white vesicle. These con- 
tinue to develop. It may require several days for all of the vesicles 
to mature. In the center there is a depression or navel which is said 
never to be absent. The closer the vesicles are to each other the 
smaller they are in size. Around the vesicles, the skin becomes 
hyperemic and the subcutaneous tissue edematous. In from 2 to 3 
days, the liquid in the vesicles becomes cloudy, owing to the presence 
of pus cells. Later they become white and the navel-like depression 
may disappear or the edema about them may increase. The pustule 
form lasts about 3 days. ; 
Diagnosis. Sheep pox is to be diagnosed by the symptoms and 
lesions. The characteristic exanthema renders it not difficult in 
typical cases. It is to be differentiated from blue tongue occurring 
in Southern Africa, from scabies and other forms of eczema. 
Prevention. Ostertag recommends the slaughter of all infected 
and suspected animals and the quarantine of farms and areas for a 
period of three months. The carcasses of the destroyed animals 
should be burned. The period of quarantine may be reduced by 
dipping the sheep in a 25% creolin or creosote soap solution. In 
Algiers a vaccine is prepared from the large pustules. 
