33 



ing that is allowed. It spreads rapidly in a flock, and few escape; 

 while the major portion die under these conditions, which are con- 

 siderably modified when the animals are allowed their liberty as 

 means of reducing actual contact. 



8. — Symptoms. 



" Sheep-pox is chai'acterized by a period of incubation which 

 may vary from a week to a fortnight. During this there are no 

 signs of disturbance, and the animal comes under the head of 

 * infected.' Certain conditions tend to modify the incubation 

 stage, and delay the appearance of symptoms. When the disease 

 is induced by inoculation, the earliest manifestations may occur 

 about the third or fourth day, but may be delayed some weeks. 

 Hot weather and confinement to close warm situations eminently 

 favour their development ; but cold, exposure, and other con- 

 ditions conducing towards a healthy tone of the system will retard 

 them, and delay their appearance until the fifteenth or even the 

 twenty-fourth day. 



" The first signs are those of dulness succeeded by febrile 

 shakes : this is the period of invasion. The skin, particularly 

 of those animals but slightly covered with wool, exhibits a 'flea- 

 bitten appearance,' each spot becoming more inflamed and 

 enlarged, and forming what is known as a papula : this is the 

 eruptive stage. The papula then ai'e elevated and transparent 

 from the eighth to the tenth day, and are filled witli a clear licfuid 

 which speedily appears turbid, denoting a change from the papular 

 to the pustular stage. The swelling is white at first, but with the 

 changes just noticed assumes a yellow colour and opaque appear- 

 ance, while the surrounding parts are very pale. Shortly, the 

 elevation becomes dilfuse and the pustule dries up ; over which 

 a scab is formed, which, when it falls off", exposes a depression in 

 the skin. 



" The constitutional symptoms run very high at times, in accord- 

 ance with the amount of eruption that takes place. In these 

 cases the papula are very abundant and unite — a condition which 

 is termed confluent. The eyes discharge a purulent secretion ; 

 they are blood-shot, and intense thirst tortures the poor creature. 

 The breathing becomes quick, discharge also flows from the nostrils, 

 the mucous membranes assume a blue appearance, breath becomes 

 fetid, and with the cutaneous exhalation is almost unbearable. 

 These symptoms suffer modification or aggravation, and the animal 

 dies about the eighth day after the eruptions appear, but before 

 the formation of lymph has taken place. It may, however, 

 occur earlier or even later ; and mild cases that are limited to 

 slight fever and a rapid transition of changes, may exhibit 

 approaching convalescence in fifteen days— others are delayed for 

 a month. 



D 



