farmer:.' institutes. T91 



may last for montlis in older ones. AVhen localized, it is recognized only 

 after the animal is slaughtered. 



Lesions.— The changes in the tissues following the invasion of the 

 bacillus tuberculosis are the formation of nodules or tubercules, gray or 

 yellowish white in color or translucent in character. In some cases these 

 nodules are distinct and easily recognized, but in advanced cases they 

 often come together and form a mass of tubercular tissue. 



In the beginning the tubercle consists of a few cells surrounding the 

 invading germs. These are soon enclosed in a zone of epitheloid cells 

 and giant cells, which in turn become surrounded by a layer of lymphoid 

 cells. The central portion of the tubercle soon dies and breaks down, and 

 as the nodule enlarges, the necrotic portion gradually increases. When 

 cut into these nodules or masses of tissue are usually made up largely of 

 yellow caseous material. Sometimes it is indurated and almost as hard 

 as cartilage. Calcareous degeneration of nodules is not often seen in 

 hogs. 



As the disease is nearly always contracted by the ingestion of in- 

 fected food the digestive apparatus and lymphatic glands are usually 

 involved. Localized lesions in the lymphatic glands (pharyngeal and sub- 

 maxillary) are very common. They become enlarged, knotty and hard. 

 When cut into they are made up mostly of old fibrous tissues with yellow 

 caseous centers scattered through it. Ulcers and miliary nodules may be 

 seen in the intestines; yellow miliary granules may be scattered through- 

 out the liver tissue, or tough nodules, yellowish white in color and vary- 

 ing in size from that of a pea to a hazel nut, may be seen; the peritoneum 

 is sometimes the seat of fine gi-anulations; and lesions the same as exist 

 in the liver may be seen in other internal organs (spleen, lungs, etc.). 

 When the disease is generalized, the muscles are sometimes affected. 



Treatment.— We must take all the precautions possible against in- 

 fecting the herd by avoiding the feeding of infected food and by keeping 

 the hog houses and pens in the best hygienic condition possible. Hogs 

 should not be fed skim milk and slops from a dairy known to have tuber- 

 culosis, and it is a very bad practice to feed hogs the carcasses of other 

 animals. When a hog has tuberculosis it should be destroyed and the 

 body disposed of in a suitable manner. 



Infectious Catarrhal Pneumonia of the Pig.— There is a form of ca- 

 tarrhal pneumonia of pigs that is without doubt of infectious character. 

 The infectious nature is established from the clinical history rather than 

 from the finding of a specific organism. It affects pigs under four mouths 

 of age principally, and is not attended with a very high death rate in 

 those over two months of age. 



When the disease is introduced into a piggery, it is almost certain to 

 attack all susceptible animals. The period of incubation, that is. the time 

 elapsing from the period of exposure to that of the development of the 



