144 POULTRY DISEASES 



tract and the spread is very rapid through the flock, as birds 

 are continually picking feed from the ground and floors where 

 contamination is sure to have taken place. 



If scraps be fed to which tuberculous sputum has found 

 its way or if the birds are allowed to devour parts of an ani- 

 mal dead of the disease, there is a liability of their contracting 

 tuberculosis. 



They may also contract the disease by the introduction of 

 a tuberculous bird into a flock. Tuberculosis among wild birds 

 has been mentioned as a possible fact. There is also danger 

 of spread from eggs from a tuberculous hen where the eggs 

 are purchased for hatching — prenatal infection. 



There is also a possibility that birds, by following tuber- 

 culous cattle, may become infected, as do hogs. It has been 

 argued that the temperature of the bird is so high (105° F. 

 to 107° F.) that it furnishes an unfavorable field for the 

 human and bovine types of germs, which thrive at tempera- 

 tures close to 98° and 101° F., respectively. It has, however, 

 been found that these germs soon adjust themselves to such 

 changes in temperature and to a certain degree to differences 

 in food. 



One case, a hen, was sent to the laboratory with the history of 

 having had access to the sputum of a person afflicted with tubercu- 

 losis. Upon autopsy small pearl-like nodules were found through- 

 out the liver, in the lung substance and over the serous lining 

 covering the intestines and abdominal cavity. A microscopic ex- 

 amination of the lesions revealed the bacillus of tuberculosis. It 

 more closely resembled the human than the avian type. 



Symptoms. — An absolute diagnosis cannot be made during 

 life from the physical signs. The symptoms observable are 

 common to many conditions, especially in the early stages 

 when there are no positive external symptoms by which it 

 may be recognized. The bird becomes emaciated. The ra 

 pidity of emaciation, like in other animals, depends on the 

 progress of the disease ; that is, the susceptibility of the bird, 

 as well as the degree of infection. 



The comb appears pale, the bird becomes dull and sleepy. 

 If the joints become affected there will be lameness, in case 

 the affection is in the legs, and swollen joints, and often in 

 affection of the skin and visi])le mucous membrane there is 

 ulceration (sores). This latter condition has been observed 

 especially in parrots. These skin lesions are made up of a 

 cheesy material (caseation necrosis), which is covered by a 

 thick, rather hard crust, whitish in color. At times these 

 crusts become rather horny in nature. 



The red blood cells in a tu])erculous fowl may be greatly 

 reduced (as low as 1,000,000), and the hemoglobin as low as 



