THE MILK SITUATION IN THE DISTRICT OF COLUMBIA. 63 



the right of the District authorities to enforce the above regulation 

 against owners of cattle, even where the product is not offered for 

 sale or used outside the owner's family. 



RELIABILITY OF TEST AFFIRMED BY AUTHORITIES. 



The tuberculin test, states Dr. Schroeder, is now almost universally 

 accepted by veterinarians as a practically infallible means of diag- 

 nosis, and w r hile we know that all cases of tuberculosis diagnosed with 

 the aid of tuberculin are not at the time dangerous and may not be- 

 come so in some instances until many months have passed, we are 

 obliged by the exigencies of the case to assume that, for all practical 

 purposes, every tuberculous cow is dangerous from the moment she 

 is known to be affected. It is not feasible, therefore, in eradicating 

 tuberculous animals from existing herds, to distinguish between 

 dangerously and not dangerously tuberculous cows. Since, however, 

 from the viewpoint of the milk supply, this may, as has been stated, 

 even when the animal is in the early stages of infection, be contami- 

 nated, the advisability of at once segregating the diseased animal 

 can not be questioned. It is interesting to note that animals of 

 entirely healthy appearance, apparently fat, sleek, and well fed and 

 with good appetites, may be already actually diseased with tuberculo- 

 sis to a somewhat advanced stage, and that as a rule cows which are 

 visibly tuberculous have very probably been dangerously affected 

 for several years. 



The profound value of tuberculin in enabling an accurate diag- 

 nosis of animals infected in a greater or less degree with tuberculo- 

 sis is due, we may repeat for emphasis, to the fact that cattle, acting 

 in all respects like healthy animals and whose bodily condition is 

 apparently better than can be expected of ideal dairy cows that give 

 large quantities of milk and have excellent appetites and no visible 

 or audible respiratory difficulties, may have their tuberculous condi- 

 tion revealed in this manner. It is only when the substances that 

 are eliminated from their bodies feces, saliva, milk, etc. are sub- 

 jected to microscopic and other tests that the proof is obtained of 

 the dangerous character of the diseased animals toward the public 

 health and the health of other animals. 



Authorities communicated with by the committee mainly agree 

 that the tuberculin test affords a wonderfully accurate diagnosis of 

 tuberculous infection in bovine animals. Dr. Perrow, health officer 

 of Lynchburg, Va., is authority for the statement that one herd of 

 150 cows in "Lynchburg showed only one reaction. On killing it 

 was manifested* that the animal reacting had one lung badly affected. 



It is interesting to note that 33 municipalities in the United States 

 now require that herds which supply their milk be tuberculin tested 

 and that the error in the application of the test has never been found 

 in any of these jurisdictions to be greater than 3 per cent. Some 

 communities which do not insist upon the application of the tuber- 

 culin test require, nevertheless, that all animals coming into their 

 jurisdiction to be used for dairy purposes be subjected to the test 

 without reaction or be shown to have recently successfully withstood 

 the test. 



During the past year laboratory experiments have been made by 

 the Bureau of Animal Industry, testing by microscopic examination 



