2y2 iOWA DEPARTMENT OP AGRICULTURE 
TUBERCULOSIS. 
DB. THOS. W. SCOTT, GOVERNMEXT INSPECTOR, WATERLOO, IOWA. 
Mr. Chairman and Gentlemen: I have been asked to address you on 
the subject of tuberculosis, a somewhat burning subject, and in doing so 
I will be obliged to confine myself to only two or three phases of the 
subject. In a paper of this character I do not deem it necessary or wise 
to go into any lengthy discussion of the pathology of the disease. Suffice 
to say that it is a highly contagious disease, that it is common to man, 
to domestic animals, birds and many of the cold blooded animals. It is 
caused by the invasion of the system by a vegetable organism, known as 
the tubercle bacillus, and can not be produced in any otlicr way. 
This bacillus may be introduced into the system in a variety of ways, 
namely, by inhalation, by direct inoculation, by ingestion, etc. The bacil- 
lus appears to be able to penetrate the mucus membrane, at least in cer- 
tain places, even when there is no wound or abrasion, and leave no trace 
or sign of its point of entrance. However, in its progress through the 
tissues it is usually soon arrested by a Ij'mphatic gland, or in some other 
manner, and then it multiplies and causes the formation of tubercles. 
After an animal, or a man either for that matter, becomes infected 
(and hereafter I shall confine my remarks more particularly to the do- 
mestic animals) the disease may develop rapidly, or it may progress very 
slowly and insiduously. Usually its progress is very slow and very sure. 
From one lymphatic gland it is carried in the lymphatic vessels to other 
lymphatic glands, or, perhaps, directly into the circulation and thence to 
the lungs or other vital organs. 
There is no question, however, but that in many cases it remains a 
local disease for some time, and sometimes remains confined entirely to 
one lymphatic gland or chain of lymphatic glands throughout the entire 
life of the animal and may never give its victim but very slight incon- 
venience or trouble. 
What are the manifestations of this disease? What symptoms, if any, 
does it present? In answering these questions, referreing particularly to 
the lower animals, I may say that in hundreds of cases, and indeed I 
might say in most of cases, there are no physical signs or manifestations 
whatever. This is one of the puzzling and perplexing phases of this dis- 
ease. Our animals, such as hogs and beef cattle, come to the shambles 
at an early age. They are quickly matured and hence most of them are 
slaughtered at from one year to three years old, with the exception of the 
cast-off or worn out dairy cow, which, of course, remains in the dairy as 
long as she can show that she is at all profitable, which, in the case of 
the tubercular victim, may not be very long. But other hogs and cattle 
go to market quite young and, as United States Veterinary Inspector, it 
is my duty to inspect quite a number of them annually, both at anti- 
mortem and post-mortem inspection, and I can say that we can reject 
very few hogs or cattle at anti-mortem inspection, but at post-mortem we 
find in this vicinity in the neighborhood of four to six per cent of the 
hogs of all classes affected. I regret that I am unable to give you the 
exact percent of all classes of cattle found in this vicinity to be more or 
