MICHIGAN ACADEMY OF SCIENCE. 
143 
usually introduced through a laceration of the oral mucosa by a spear 
of hay or grain. The disease is characterized by the formation of 
nodules which break down and discharge through sinuses, these sinuses 
may heal to break out again in another place. If the jaw alone is 
affected the course of the disease is slow, the animal becoming very 
emaciated through inability to masticate. When metastases occur in 
the liver and other internal organs the functions are rapidly impaired 
and the symptoms are augmented. Death finally occurs. The specific 
organism may be found in the pus in the form of small yellow granules 
about the size of a pin-head which, under the microscope, show the char¬ 
acteristic form of the ray fungus. 
Tuberculosis. The causative factor in this the most common condi¬ 
tion of diseased meat is the tubercle bacillus. The disease is commu¬ 
nicable and evidences definite and characteristic lesions. The order of 
frequency of primary infection is: 
(1) The lymphatic system. 
(2) The pleura and peritoneum. 
(3) The lungs. 
(4) The liver, kidneys and brain. 
The udder of cows is frequently affected and many cases of simple 
mastitis are really tuberculosis. The site of the primary lesion depends, 
of course, on the avenue of infection. 
If the serous membranes become infected they are covered with tuber¬ 
cles which coalesce, forming large nodules; this condition is. known as 
‘‘the grapes” or “angle berries,” and in Germany as pearl disease or 
Perl sucht. 
The course and symptoms of the disease depend on (1) as to whether 
the animal is predisposed, (2) the site of the disease and the organs 
involved, (3) the occurrence of secondary infection. 
When the lung is affected the first symptom is a rough, weak cough, 
the respiration becoming weak and embarrassed. A continued fever with 
a marked diurnal exacerbation is also characteristic. If the udder is 
affected tubercle bacilli will be found in the milk, and even when no 
lesion can be demonstrated in these glands their presence in the milk 
has been detected. The use of tuberculin has done much to assist in the 
diagnosis of this condition in the living animal, and it should be em¬ 
ployed in all doubtful cases, as it is harmless to nontubercular animals. 
Glanders is a highly infectious disease, communicable to all animals 
with the exception of cattle and to the human. It may run an acute 
or chronic course and is most common in horses. 
Variola Ovina, or smallpox, occurs in sheep and is exceedingly in¬ 
fectious and communicable to the human. It presents the same lesions 
and symptoms in the animal as it does in man. 
Phthisis in sheep is due to an infection of the lung by the parasite 
strongylus filaria. The disease produces great emaciation and is not 
transmitted to the human. 
Fluke disease affects cattle sheep and horses and is due to an infec¬ 
tion by the distoma, the embryos of which are taken in with the drink¬ 
ing water which becomes contaminated by fecal matter. As the disease 
occurs in the human, infection taking place through the same source, 
all water used for drinking purposes should be carefully guarded from 
contamination. 
