SYMPTOMS. 155 



Symptoms. — The general symptoms or distm'bances consti- 

 tuting the primary fever in horse-pox are usually very slight 

 — so slight that they rarely attract observation. The period 

 of incubation is somewhat variable ; when resulting from in- 

 oculation, it rarely extends beyond eight days. 



For two or three days previous to the appearance of the 

 local phenomena, general disturbance, as indicated by slight 

 rigors and staring coat, may be attractive ; in the greater 

 number, however, even these premonitory symptoms of illness 

 are unnoticed : and it is not until the animal refuses his food, 

 and appears either disinclined or unable to eat, that any fear 

 of illness is felt. At this time the pyrexia is distinct, and 

 seems to vary in accordance with the seat of the local erup- 

 tion. 



It is said that the constitutional disturbance is most marked 

 when the eruption is situated on the extremities, and least so 

 when this is developed in connection with the skin and mucous 

 membranes of the head. When the skin of the limbs becomes 

 the seat of the eruption, there is an increase in its vascularity ; 

 if colourless, the first indication of disturbance is the appear- 

 ance of red patches, which shortly become slightly elevated, and 

 feel hard or firm when pressed between the fingers. As it ad- 

 vances in growth this elevation becomes depressed in the 

 centre, elevated at the edges, with an encircling zone or 

 areola. 



This umbilicated appearance of the eruption, and its being 

 surrounded by an areola, is usually characteristic of the 

 variolous papule in most animals. In three or four days 

 after the appearance of the pimple, the contained fluid or 

 serous material becomes more opaque, the epidermis dry and 

 crust-like, but movable, and if abraded, easily detached from 

 the soft or fluid state of the tissue beneath. 



When abraded and detached by friction, the removal of the 

 crust or epidermic thickening is followed by a discharge for 

 some days of a hmpid, straw-coloured fluid, which gradually 

 subsides, the small circular cavity or depression filling by 

 granulation. When not detached by force, the natural pro- 

 cess of cicatrization generally detaches this crust, with little or 

 no suppuration, in from twelve to twenty days. 



AVhen from the situation of the pustules in the flexures of 



