DISEASES OF SWINE 451 



anything that has a tendency to weaken the system of the animal 

 renders him a more fit subject for hog cholera. 



While the disease has no respect for the age, size or breed of 

 hogs when it once starts in a herd, it is usual for an outbreak to be- 

 gin with the younger pigs and later to attack the more mature ani- 

 mals. But this is not always true. Hog cholera is most prevalent 

 in the fall of the year and early winter. During the cola weather 

 the cases, as a rule, become more chronic, do not die so suddenly, and 

 a greater per cent of them get well. (Kan. B. 163.) 



Symptoms. Hog cholera is generally prevalent during fall and 

 early winter. It is an infectious disease in which the lymphatic 

 glands, intestines, lungs, kidneys, and liver are generally inflamed. 

 The inflammations are hemorrhagic in character, the lymphatic 

 glands assuming a grayish-red character, while the discoloration in 

 other organs and tissues may vary in size from very small red spots 

 to large irregular dotted areas. 



There are two forms of hog cholera: acute and chronic. In 

 acute form the disease is very virulent and animals affected die from 

 within a few hours to a few days after showing characteristic symp- 

 toms. In chronic form the disease does not seem to be so virulent 

 and usually lingers from a few weeks to even months ; animals finally 

 dying in an emaciated condition or recovering in some few cases. 

 The length of time required for hogs to become sick after being ex- 

 posed to the disease varies from 6 to 14 days or may be even longer. 



Lack of appetite may be the first disorder noted, followed by 

 rapid and labored breathing. Animals infected may be found lying 

 in their beds showing little disposition to move, and upon being 

 forced to walk show weakness in their hind quarters, a staggering 

 gait with arched back, and after moving about for a time may fall 

 sprawling with labored breathing showing in the flanks. Constipa- 

 tion at the outset is usually followed later by diarrhea. Purplish 

 and reddish discoloration of the skin appear on the under side of the 

 belly and behind the ears, especially noticeable on white pigs. The 

 normal temperature of the hog is 103 degrees F., but in cases of hog 

 cholera it may be as high as 105 or 106 degrees and occasionally 

 higher. Some pigs die before showing few if any outward symp- 

 toms of the disease. (N. J. L. S. C. Cir. 1.) 



The beginning of hog cholera in a herd is marked by the sick- 

 ness of one or two hogs. There is nothing particularly characteris- 

 tic in the symptoms displayed, and the presence of the disease may 

 not be suspected until a week or two later, when other hogs are at- 

 tacked. As the number of sick hogs increases the opportunities for 

 the well animals to contract the disease are multiplied, and in a com- 

 paratively short time all hogs exposed to the contagion will be 

 attacked. 



The symptoms observed in particular cases will be influenced by 

 the virulence of the germ which is responsible for the attack, and also 

 by the resisting power of the hogs in the herd. If this resisting power 

 is low, or if the germ which is the cause of a particular outbreak is of 

 high virulence, we may have in such a herd a typical manifestation 



