790 BOARD OF AOKICULTURE. 



conuiion in cattle. 'J lie disease is more ofteu seen in young than In old 

 liiijis and is generally acute and generalized. 



Causes.— The specilic cause of tuberculosis is the bacillus tuberculosis, 

 which was discovered by Koch in 1882 and can be found in the nodules 

 and tubercules in the tissues? of diseased hogs. These bacteria usually 

 occur in the form of slender rods averaging from 2u. to 5u. in length, and 

 have rounded ends. These may be seen singly, in pairs and in small 

 bundles, and do not form spors but vacuoles. There is probably no 

 disease -producing germ which undergoes greater modifications under 

 various conditions of environment than this. 



Pigs generally contract the disease by eating infected food; skim milk, 

 butter-milk and slops from the dairy. Young pigs may become diseased 

 from sucking a tuberculous mother. The eating of the tubercular car- 

 casses may also cause it. Infection may take place through the inspired 

 air, and when tubercular hogs are introduced into a herd all the hogs 

 in the pen may contract the disease. 



Predisposing conditions are veiy important factors, and such con- 

 ditions as act unfavorably on the constitution of the pig, will, if the germs 

 are present, favor the development of the disease. Close pens, filth, un- 

 natural bringing up, early forcings, etc., all favor its development. Im- 

 proved breeds of swine are said to be more predisposed to the disease 

 than the common breeds. Infection has been known to occur by way of 

 wounds, especially castration. 



Symptoms. — These will vary according to the organ affected. In pigs 

 the disease is often acute and generalized. Generally the symptoms are 

 not well manifested or the infection may be slight and the disease not 

 recognized by the owner, unless a post mortem examination is made on 

 some of the dead animals. In young pigs that have become infected by 

 sucking a diseased mother, symptoms of intestinal tuberculosis may be 

 manifested. The pig becomes runted, pot-bellied, and emaciated. The 

 visible mucous membranes are pale and the skin presents an unthrifty 

 appearance, and may become covered with crusts. Digestive disorders 

 occui', such as diarrhea, bloating and vomiting. Manipulating the ab- 

 domen may cause the animal pain, and sometimes a hard, knotty mass, 

 representing a bunch of tubercles, is felt. The pig is feverish at times. 



If the lungs are involved there is-a cough. This becomes more annoy- 

 ing as the disease progresses, sometimes the pig almost chokes. The 

 breathing is quickened and labored. 'Frequently the superficial lymph 

 glands in the region of the pharynx are affecfod. 



In tuberculosis of the brain, nervous disturbances are noted, such 

 as turning round and round, convulsions, spasms of muscles and paralysis. 

 Only part of the body or certain groups of muscles are involved. The 

 head may be held obliquely, the snout drawn to one side and the ear 

 droop. 



The course of generalized tuberculosis is short in young pigs, but 



