Aids to stockowners / by J. Walker.

  • John Walker
Date:
1930
Catalogue details

Licence: In copyright

Credit: Aids to stockowners / by J. Walker. Source: Wellcome Collection.

    39/198 page 21
    21 Preventive inoculation is largely resorted to in this Colony. Tt consists of inoculation of a pure culture virus into the sub¬ cutaneous tissues of the tail. Vaccines of different virulency are prepared at the Laboratory for issue. I he virulency of a pure culture vaccine decreases after a number of sub-cultures; at about the twenty-fifth generation it produces little or no mortality, whereas the reactions which occur Iroin ihe original culture and early sub-cultures of the same strain oi virus are sometimes severe and difficult to con¬ trol. and some mortality may he experienced; the use of the more virulent vaccine is not recommended in herds in which the disease does not actually exist. Previous to the introduc¬ tion of the pure culture vaccine, the sero-fibrinous exudate (lymph virus) collected from the lung or pleural cavity of an affected beast was used for preventive inoculation, but owing to the losses which sometimes followed its use and the difficulty of maintaining supplies, the pure culture vaccine, when labora¬ tory facilities exist for its preparation, is now substituted for the lymph virus. The following method of obtaining supplies is sometimes resorted to where laboratory facilities do not exist for preparing the pure culture vaccine or it is difficult to obtain lymph virus from a naturally affected beast, viz. a susceptible young beast is inoculated behind the shoulder with a pure culture virus, and this is maintained by passage through susceptible young cattle. When lymph is required a reacting beast is slaughtered and the virus collected and preserved in glycerine; one cubic centimetre of the glycerinated virus being inoculated into the subcutaneous tissues of the tip of the tail. 1 his method necessitates supplies of large numbers of susceptible cattle, if large quantities of virus are required. The method is costly ; in some cases little lymph is obtained from the reacting beast, moreover the virus is likely to produce marked reactions and some mortality occurs when used in the practice. Directions for the Use of Pt.euro-pneumonia (Pure Culture) Vaccine. Dote and Properties.—The dose is 1 c.c. d’he vaccine is a pure culture of the organism of bovine pleuro-pneumonia in beef bouillon, Martin’s peptone additioned with ox serum. It has a more or less yellowish colour and a cloudy ap¬ pearance. It should have no offensive odour.
    digitised image 1
    digitised image 2
    digitised image 3