INFECTIOUS DISEASES OF CATTLE. 485 



blood clotting in the syringe, but with practice and promptness this 

 can be easily overcome. 



The second method is better suited for the inoculation of a large 

 number of cattle or where the immune animal is at a distance from 

 the. cattle to be immunized. 



The preliminary steps — the clipping of the hair, disinfection of 

 the skin, placing the rope around the neck to distend the jugular 

 vein, and restraining the animal — are the same as for the first method. 

 In puncturing the vein it is advisable to use a small trocar and canula 

 after sterilization in a 5 per cent carbolic-acid solution, and, when 

 the vein has been entered, to draw out the trocar, allowing the blood 

 to flow through the canula into a perfectly clean and sterile vessel. 

 After sufficient blood has been drawn for the animals to be injected, 

 a clean stick, previously sterlized by boiling in water, is placed in 

 the vessel containing the blood and the latter is stirred for ten min- 

 utes or so or until the fibrin in the blood is whipped out. The remain- 

 ing blood, known as defibrinated blood, is then inoculated under the 

 disinfected skin of the animals to be immunized, as in the first 

 method. This blood should be used as early as possible after draw- 

 ing, to prevent it from becoming contaminated and decomposed. 

 The place where this injection is made is immaterial, but for conven- 

 ience a point just behind the shoulder is usually chosen. The dose 

 and number of injections vary with the individual animals. As a 

 rule, it may be stated that 1 cubic centimeter should be injected into 

 an old animal coming into the infested district, 2 cubic centimeters for 

 a 2-year-old, and 3 cubic centimeters for an animal 9 to 15 months old. 

 It will be observed that, unlike the usual custom of applying treat- 

 ment, the older animals take less than the young ones owing to their 

 greater susceptibility to the disease. "Where an animal has reacted 

 well to a first injection and shows a very high temperature, great 

 reduction of red blood cells, or other symptoms indicative of reac- 

 tion, it will not be necessary to repeat the injection, but in those 

 cases where the reaction is slight, a second injection should follow 

 after an interval of forty days, and, if need be, a third injection after 

 a similar lapse of time, always increasing the size of dose 50 per cent. 

 A thermometer, to indicate the course and severity of the disease, 

 is indispensable in this work. Usually, after three to ten days, sonie- 

 ' times longer, the inoculated animals show a mild type of Texas fever, 

 which runs a course of from six to eight, days and is followed in about 

 thirty days after the injection with a second attack of a milder 

 character than the first. After forty days, when the animal has 

 entirely recovered from the inoculation, a second injection may be 

 given to increase its immunity. In some cases a very severe type of 

 fever follows the first inoculation, requiring careful nursing and 

 treatment, as suggested above. A second, milder attack follows 

 usually in about thirty to forty days, after which the animal need 

 have no further inoculations. It is advisable to prevent any ticks 



