602 IOWA DEPARTMENT OF AGRICULTURE. 



and some experience properly to determine the presence or absence of the 

 disease. If you cannot command the services of a graduate veterinarian 

 to do the work you should not hesitate to do it yourself, and to that end 

 the following instructions will be found useful: 



In the first place, the quality of the tuberculin to be used is all- 

 important, and there is much distressing evidence to show that commercial 

 tuberculin is not always reliable, but frequently fails to detect the 

 presence of the disease, and owing to this cause the disease has for 

 years spread gradually in many a fine herd, whereas by use of govern- 

 ment tuberculin its presence might have been instantly detected and the 

 plague promptly stamped out. 



The tuberculin should be fresh as well as reliable, and then should be 

 used intelligently. If old it may be inert or weak and so prove useless 

 as a detecting agent; if used unintelligently it may fail to detect the 

 disease or apparently detect it when really absent. 



Tuberculin acts by causing a marked, gradual increase in the tem- 

 perature of the tuberculous cow tested, and after attaining the maximum 

 the temperature as gradually falls. A very sudden rise and a fall that is 

 sudden, each within a short period of time, scarcely can be considered 

 perfectly indicative of tuberculosis. Before accepting such spasmodic 

 increases as indicative of the disease all circumstances and conditions 

 affecting the animal at the time should be carefully taken into account, 

 and it is in this phase of the work that experience and special skill are 

 most required. 



For the work of testing one requires, in addition to the supply of 

 reliable tuberculin, a strong clinical thermometer, several short, sharp 

 hollow needles of comparatively large calibre and a strong graduated 

 hypodermic syringe. All of these may be purchased from any dealer in 

 veterinary instruments. 



Before commencing the test the cows should be accustomed to the 

 stable, if they have been running out of doors, and should have quited 

 down and become accustomed to their new quarters if shipped in from a 

 distance. It is best not to test cattle in hot weather, as their temperature 

 is very easily affected by heat and indeed by all marked extraneous, 

 internal and incidental influences such as change of food, fright, drinking 

 of cold water, change of milkers, coming in heat, nearing calving time or 

 effects of calving or retention of afterbirth. It is well, therefore, not to 

 test a cow that is in any way sick, in heat, nearing calving, just calved, 

 retaining her afterbirth, affected with garget or greatly excited and, 

 therefore, showing an abnormally high temperature from any cause or one 

 of those mentioned. 



When all is in readines for the test preliminary temperatures of each 

 cow should be taken by inserting the thermometer in the rectum for not 

 less than five minutes. The mercury in the thermometer is first to be 

 shaken down to 100 Fahr. and on removal the column is to be 

 carefully read and the reading set down on a card or paper opposite the 

 cow's name. The first temperature is to be taken before 8 o'clock a. m., 

 the second at noon and the third at 6 p. m. or thereabouts, and these 

 three temperatures show the average normal temperature of the cow 

 before injection of the tuberculin. No cow that shows a temperature of 



