INFECTIOUS DISEASES OF CATTLE. • 509 



opening in the needle. Attach the disinfected syringe to the needle 

 with piston in and gradually draw out the piston until the chamber 

 of the syringe is full of blood, when the needle is withdrawn. The 

 blood, before it has had time to clot, is immediately injected into the 

 animals to be immunized and which have been previously tied or 

 restrained, the hair clipped, and the skin disinfected at the seat of 

 injection in the region of the shoulder. Inject then from 1 to 3 c. c, 

 according to the age of the animal, under the skin of each animal 

 until the blood is exhausted. When more animals are to be inocu- 

 lated than one syringeful will inject, the operation may be repeated 

 in the same manner. The only objection to this method is the possi- 

 bility of the blood clotting in the syringe, but with practice and 

 promptness this can easily be 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 cannula 

 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 cannula into a perfectly clean and sterile vessel. 

 After sufficient blood has l>een drawn for the animals to be injected, 

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

 the vessel containing the blood and the latter is stirred for 10 min- 

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

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

 disinfected skin of the animals to be inmiunized, 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 con- 

 venience 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 obseiwed that, unlike the usual custom of applying 

 treatment, the older animals take less than the young ones, owing to 

 their greater susceptibility to the disease. Where an animal has re- 

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

 great reduction of red blood cells, or other symptoms indicative of 

 reaction, 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 40 days, and, if need be, a third injection after 



