DISEASES OF SWINE AND OTHER ANIMALS. 57 



INCUBATION OF THE DISEASE. 



Our experiments have sliown this to vary g-reatly, though in the great 

 majority of cases it termiuated in from three to seven days after inocu- 

 lation. As shown in the table appended, one sickened on the tirst day, 

 three on the third, two on the fourth, one on the fifth, two on the sixth, 

 four on the seventh, and one each on the eighth and tliirteenth days 

 respectively. A comparison of these results with those obtained else- 

 where seems to show that we have reached the two extremes. Dr. Sut- 

 ton, observing the result of contact alone in autumn, sets the period at 

 from thirteen to fourteen days ; my own observations in Scotland, in 

 summer, indicated seven to fourteen days ; Professor Axe, in London, 

 in summer, concluded on five to eight days ; Dr. Budd, in summer, four 

 to five days ; and Professor Osier, in autumn, four to six days. 



SYMPTOMS. 



The cases observed were of all degrees of severity, from a slight access 

 of fever, with some loss of appetite, irregidarity of the bowels, and alter- 

 nations of heat and cold on the surface, to violent attacks, terminating 

 fatally after eleven days' illness. 



Early symptoms. — In an average case, one of the earliest signs of ill- 

 ness was an elevated temperature of the body, amounting to one or two 

 degrees above the former indications furnished by the same animal. 

 This qualification appears requisite, as the temperatures of healthy -pigs 

 were found to vary widely imder different conditions of life. After act- 

 ive exercise or excitement 104° F. is not unfrequent, while in a close 

 pen where they are quiet and still, 100° to 102° F. is quite as common. 

 On more than one occasion, when a pig got accidentally fixed in a nar- 

 row space where he had barely room to stand, the temperature was re- 

 duced to 99"^ and even 98° F. The body heat was raised by a hearty 

 meal and lowered by abstinence. Generally a sudden rise of tempera- 

 ture and saturation of the atmosphere with moisture led to an elevation 

 of the body heat, in other cases a reduction of the temperature of the 

 air led to the same phenomenon. (See table of Meteorological Observa- 

 tions and Temperatures.) In connection with the rise of temjierature 

 there was generally a diffuse redness of the skin, with increased warmth, 

 alternating with cold, especially in the ears, nose, tail, and limbs. The 

 pulse usually rose perceptibly, sometimes reaching 120 per minute, while 

 the breathing was little if at all affected. The snout was often drawn 

 back, giving a wrmkled or pinched appearance to the face ; the move- 

 ments were less active, sometimes decidedly stiff and slow ; there was 

 ])erceptible faUing off in appetite, and the bowels were usually costive. 



Disease at its height. — The temperature rose in most cases to 105° F., 

 and exceptionally only to 107^ or 108c> F. (Dr. Osier records 110° F.), 

 to be followed after a variable length of tune (three to twenty days) by a 

 a descent to the natural standard, or even lower. The pulse also rose to 

 120-130, and the flushes of heat on the skin were much more frequent and 

 extreme. At the same time certain changes appeared in the skin, vary- 

 ing greatly in degree in different cases, but which may be described as 

 follows : 



First. A pink or scarlet rash in spots averaging about one-tenth inch 

 in diameter, but often becoming confluent so as to form an extended 

 blush. Many such spots disappeared momentarily under pressure, show- 

 ing that the minute blood-vessels were not yet completely blocked, but 

 only dilated. Many, however, could not be even temporarily obliterated 



