90 DISEASES OF SWINE 



Chickens, especially, very commonly range from one feed lot to the 

 other in search of food, and carry on their feet the infected dis- 

 charges of the sick herd to scatter them in the pens of the healthy 

 herd. It is not long until one or more of the healthy animals takes 

 in through the mouth enough of the disease-producing virus to set 

 up the disease in his own body, and he then rapidly spreads the 

 disease to the other animals of the herd. 



Pigeons are another very common source of carrying this invis- 

 ible virus from one hog lot to another. Nearly every farm in the 

 Central West has a flock of a dozen or more pigeons roosting about 

 the barns, and these birds travel from one feed lot to another in 

 search of grain. As in the case of the chickens, they unconsciously 

 often become the carriers of infected manure from one feed lot to 

 another, and thus prove the source of the disease in other herds. 

 As these birds frequently travel considerable distances in search 

 of food, they may be the means of scattering the infection in a herd 

 a mile or more away. 



Injected Bowel Discharges. — When the disease becomes devel- 

 oped in the body of the animal, lesions are especially produced in 

 the intestines, both small and large, as will be fully described in the 

 succeeding pages. These ulcers are continuously discharging into 

 the bowel large amounts of the hog-cholera virus, and this is carried 

 out with the bowel movements to be scattered over the ground with 

 the manure. Unfortunately, hogs are often so confined that in the 

 eating of their food it is necessary for them to also eat a considerable 

 amount of their own fecal matter. In this way the infective virus 

 is rapidly spread from one animal to the other, entering by the 

 mouth and setting up an infection of the bowels in the second 

 animal. 



Impure Water. — Where hog wallows are present in the feed lot 

 considerable amounts of this fecal matter are passed in, or find their 

 way into, the water and mud of the wallow, and thus this water be- 

 comes infected. Hogs or pigs which may drink this germ-laden 

 water thereby carry the infected discharges to their own bodies and 

 are rapidly attacked by the disease. 



In Urine. — Hog-cholera is by no means a disease which is 

 limited in its distribution to the intestines, as we will find when we 

 take up the postmortem examination of animals dead of this dis- 



