HEALTH AND DISEASE OF POULTRY 577 



joints, which would account for the lameness. In the last stages 

 of sickness, the affected bird crouches, apparently from weakness. 

 The pale comb, ruffled feathers, unnatural gait, and general atti- 

 tude are features that attract attention to the victims of the disease. 

 A very small percentage of affected fowls show tuberculous nodules 

 on the skin of various portions of the body. These may consist of 

 single spherical masses each surrounding the root of a feather, or 

 more often consist of larger masses. These nodules, when occurring 

 upon the head, should not be confused with the swellings that ap- 

 pear on the head in advanced cases of roup (swell head), nor with 

 the wart-like lumps found on the head in chicken-pox. Facts con- 

 cerning the length of time that fowls usually live when infected 

 have not yet been secured. One hen, inoculated by injecting crushed 

 tuberculous liver into the abdominal cavity, died in six weeks of 

 generalized tuberculosis. 



Lesions. In most cases the liver is affected. It is found en- 

 larged and studded throughout with yellowish-white nodules of a 

 more or less cheesy consistency, varying greatlv in size and number 

 in different cases. The nodules are very readily separated from the 

 surrounding liver tissue. Poultrymen are familiar with the condi- 

 tion, and refer to it as "liver complaint" or as "spotted liver." The 

 spleen, in health a small rounded purple organ about half an inch in 

 diameter, is frequently affected with tuberculosis, and in conse- 

 quence greatly enlarged. Rounded masses of varying size may be 

 found in the walls of any part of the intestine. The mesentery, 

 the thin membrane to the border of which the intestine is attached, 

 is occasionally dotted with nodular masses. The lungs are very 

 rarely affected. Alterations of the bones, joints, or other organs 

 occur more rarely, and are not so readily recognized as the changes 

 described. Most hens badly affected with tuberculosis are very lean, 

 but exceptions have been observed. 



Spread of Tuberculosis Among Fowls. Tuberculosis is an in- 

 fectious disease caused by organisms, known as tubercle bacteria, 

 which gain entrance to certain organs of the body and multiply 

 there. The nodular growths (tubercles) so constantly found in 

 tuberculosis are caused by the presence of these bacteria in the 

 affected regions. The spread of tuberculosis from one fowl to an- 

 other occurs only when conditions permit the transfer of the live 

 tubercle bacteria more or less directly from the diseased to the 

 healthy. The presence of tubercular growths in the walls of the intes- 

 tine and in the liver suggests that the tubercle bacteria enter the 

 body with the food. The rarity with which tuberculosis occurs in 

 the lungs of fowls would indicate that infection by the inhalation 

 of tubercle bacteria occurs rarely, if at all. 



An examination of the tubercular growths located along the 

 walls of the intestine leads to the conclusion that the tubercle bac- 

 teria are liberated from the body along with the droppings. In a 

 large percentage of bad cases of tuberculosis, tubercles will be found 

 to have a cavity in the center which communicates with the inte- 

 rior of the intestine. A microscopic examination of the contents of 



