GENERAL REMARKS ON DIAGNOSIS 187 



a pretty safe bet that we are at the start of an outbreak of cholera. 

 When hogs get sick without any apparent cause in the matter of 

 diet or housing, cholera is the most Ukely agent. 



If, in addition to these symptoms, it is found that new animals 

 have been added to the herd within the past few weeks, or if an 

 epidemic of cholera be raging in the neighborhood, then our sus- 

 picion of cholera is indeed well founded, and it is almost a certainty 

 that this disease is making a start in the herd. 



If the animals are closely observed, it is quite likely that there 

 will soon be noted the black-colored diarrhea, the cough, muscular 

 weakness, staggering gait, swollen ears, red spots on the skin, 

 swelling of the eyehds, sensitiveness to touch, and great thirst — all 

 of which go to make the diagnosis more certain. 



If we now open up the dead body of one of the affected animals 

 we will be very likely to find swollen lymphatic glands which are 

 filled and discolored with blood; enlarged, softened spleen; small 

 pin-point red spots in the kidneys; ulceration and inflammation 

 of the bowels, especially the lower part of the small bowel and the 

 large bowel; redness and inflammation of the inner coat of the 

 bladder; small red spots in the muscle of the heart, and these same 

 small red splotches on the surface of the lungs. Our diagnosis 

 can now no longer be in doubt. The case is unquestionably one of 

 cholera. 



It is only in those cases which have a tendency to occur at the 

 beginning of an outbreak, where the animal shows but little evi- 

 dences of being sick, and shows little or no change when opened up, 

 that we are Ukely to have trouble in making a diagnosis. These 

 cases, which have been described under the head of the very severe 

 form, are often quite puzzling, and a diagnosis simply cannot be 

 made without waiting for further cases to develop, or by injection 

 of some of the blood from the dead animal into healthy pigs and 

 awaiting the outcome. 



There is another type of cases in which there may be consider- 

 able trouble in arriving at a diagnosis. These are the ones in which 

 there are no changes to be found in the organs of the belly cavity, 

 and in the lungs we find all the signs of a pneumonia. These cases 

 are often puzzling, and it takes the aid of laboratory tests often to 

 settle the matter. In a general way, however, it may be said that 



