500 DISEASES OF CATTLE. 



immune animal which is in good health and which is infested with 

 fever ticks or had them the preceding year. Fasten the animal se- 

 curely, either by tying, throwing, or by placing in a chute. Clip the 

 hair from a space about 4 inches in diameter over the jugular vein 

 on the upper third of the neck, wash the skin thoroughly with a. 5 

 per cent solution of carbolic acid, and then fasten a strap or rope 

 around the neck below the hairless area and draw it tight in order 

 that the blood in the vein may be stopped, causing distension. With 

 a large, hypodermic-syringe needle, previously sterilized in a 5 per 

 cent carbolic-acid solution, puncture the vein at a slight angle, direct- 

 ing the point forward. When the needle enters the vein the point 

 can be rotated freely in contrast to the restricted movements if still 

 in the tissues, and the blood will either drop or flow from the 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 the syringe is full of blood, when the needle is withdrawn.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. From a yearling in fair con- 

 dition a pint of blood may be taken without harm, while double this 

 quantity may be taken from a 2-year-old, and four or five times as 

 much from a 3-year-old or upward. Inject then from 1 to 3 cubic 

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

 each animal until the blood is exhausted. When more animals are 

 to be inoculated than one syringeful will inject, the operation may be 

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

 the possibility of the blood clotting in the sja-inge, but with practice 

 and promptness this can easily be prevented. 



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 preliminar}'' 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 can- 

 nula after sterilizing 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 attached to a rubber tube into a perfectly 

 clean and sterile vessel containing a 5 per cent solution of citrate of 

 potassium or sodium, to prevent the coagulation of the blood. The 

 quantity of citrate solution in the container should be one-twentieth 

 of the quantity of blood which it is desired to collect. After sufficient 

 blood has been drawn for the animals to be injected, a cork is phu^ed 

 in the top of the bottle through which passes a long rubber tubing. 



