April, 1910,] 



343 



Live Stock. 



rinderpest and is immune for all time. 

 The blood serum contains the normal 

 anti toxins of immune animals, which 

 must now be stimulated to much greater 

 activity. 



The immune animal is maintained 

 under good care and careful feeding until 

 normal tone and good flesh is recovered, 

 and then injected with a larger dose of 

 virus, 10 cubic centimeters being given 

 at this time. Neither this nor any of 

 the succeeding injections is followed by 

 any visible reaction. About ten days 

 later, 100 cubic centimeters is injected, 

 and ten days later this is followed by 

 600 cubic centimeters. A week later, 

 the animal is bled the first time. Sub- 

 sequently, at certain intervals between 

 bleedings, injections of 1,000, 1,500, 2,000, 

 5,000, and 3,000 cubic centimeters are 

 given. Three bleedings are made in as 

 many weeks between each of the series 

 of injection of virus. Following the last 

 bleeding after the injection of 3,000 cubic 

 centimeters of virus, the work of im- 

 munizing the animal is completed and it 

 is sold at public auction, The process 

 of hyperimmunization could be carried 

 a few steps further, but it is abandoned 

 at this stage, the cost of the virus being 

 out of proportion to the advantage of 

 maintaining the same animal in the 

 herd. 



In the production of any serum it is 

 necessary to use large amounts of the 

 virus of the disease against which the 

 serum is to operate. In some cases the 

 germ may be isolated and grown arti- 

 ficially, but this is not true of rinder- 

 pest. The only known method of ob- 

 taining rinderpest virus is from the 

 bodies of sick animals. A quantity of 

 virulent blood must be available about 

 twice a week. For this purpose small 

 male cattle are infected with rinderpest 

 and bled to death at the. stage wnen 

 the temperature is at maximum height, 

 when the blood contains the most power- 

 ful toxins, and more, blood may be 

 obtained than at a later period when 

 the animals are emaciated by the as- 

 sault of the disease. Two hours before 

 death, 10 to 15 liters of weak saline 

 solution is introduced into the abdomi- 

 nal cavity at body temperature, and is 

 secured after death. It is used for in- 

 jection in the same manner as the blood, 

 being of nearly equal virulence, and 

 producing similar reaction. By the use 

 of this abdominal fluid we double the 

 quantity of virus obtainable from each 

 animal, reducing by one-half the expen- 

 diture for animals for virus. This class 

 of animal is bled to death from the 

 carotid artery. 



In bleeding for serum the animals are 

 confined on an operating table and the 



blood withdrawn from the jugular vein 

 by me'ans of hollow needles connected 

 by rubber tubes to special serum flasks, 

 from which the air has been exhausted 

 to facilitate the passage of blood. Three 

 liters is usually taken from each animal 

 at one bleeding. No ill-effects attend 

 the operation, unless a slight dizziness, 

 that is occasionally observed, is worthy 

 of mention. The blood is received into 

 tall cylindrical flasks, kept at room 

 temperature for six hours and then 

 placed in cold storage for the balance 

 of twenty-four hours. During this time 

 the blood coagulates, a firm clot drawn 

 by means of side tubes with which the 

 flasks are provided, and is ready for 

 use after being passed through porous 

 filters for sterilization. For shipment 

 into the provinces the serum is put up 

 in bottles of 300 cubic centimeters, 

 enough for the inoculation of six ani- 

 mals. Every flask, bottle, tube, and 

 instrument used in connection with the 

 production of serum is subjected to 

 sterilization by steam heat, and every 

 possible precaution taken to prevent 

 contamination. 



The important essentials for satisfac- 

 tory serum animals are size, youth, 

 docility, general soundness, and sus- 

 ceptibility to rinderpest. Chinese steers 

 are in many ways the best animals in 

 the East for serum purposes, but very 

 few of this type have been available 

 during the past year because of the 

 prevalence of infectious diseases at the 

 sources of supply. The serum herd is at 

 present made up largely of Indo-Chinese 

 animals, which are larger but more dffi- 

 cult to handle and maintain in good 

 condition, The cattle are highly fed, as 

 otherwise the continual bleeding would 

 result in emaciation. They are stalled 

 in large open sheds, being allowed 

 several hours' exercise in the pastures 

 each day, excepting one day immediate- 

 ly preceding and one day following 

 bleeding or inoculation. It might be 

 said that they enjoy their existence at 

 the laboratory, as it is certainly an easy 

 one. Each animal is retained for about 

 a year and then sold, bringing consider- 

 ably more than its purchase price, ..the 

 added value lying in its immunity to 

 rinderpest and good condition upon dis- 

 charge from the herd. 



At present the serum herd is composed 

 of about three hundred head, all of 

 which are in actual use for serum pro- 

 duction. With this large herd the 

 weekly production has averaged 180 

 liters, or sufficient to inoculate over 3,000 

 cattle or carabaos with the usual dose 

 of 50 cubic centimeters. 



