The inoculated area having been cleansed with boiled water and carefully dried, the little crusts covering the inoculation wounds are loosened and the wounds themselves gently scraped with a special curette of small size. The exuded liquid is very active.
The base of each swelling is then grasped in a little special clamp, which acts like a pressure forceps and causes the discharge of a further large quantity of active vaccine lymph. All the material thus obtained is mixed; an equal quantity of neutral glycerine is added, the whole is finely triturated, passed through a cloth, and stored in little sterilised glass tubes, which are hermetically sealed.
The vaccine thus prepared retains its activity for from five to eight months, if kept from the action of heat and light. Accidental germs which may have developed in the wounds and thus gained entrance to the vaccine gradually lose their activity. After from forty to sixty days the vaccine may be regarded as absolutely pure and incapable of producing accidental suppuration, as sometimes occurs when fresh vaccine is employed.
The old electuaries, dried vaccines, vaccine pastes, etc., have been almost entirely given up, the above method always yielding a pure and active vaccine. Vaccination with calf lymph should always be preferred to vaccination from arm to arm, in view of possible transmission of grave disease, such as syphilis.
TETANUS.
Tetanus is a disease characterised by tonic contraction of the muscles of one or more limbs or of all the muscles of the body.
Causation. It is due to the growth of Nicolaïer’s bacillus in some part of the body (in accidental wounds, in the uterine cavity after parturition, etc.), and the contraction of muscles is due to toxins (elaborated by the microbe), which have a selective affinity for the nervous centres.
These toxins, secreted by bacilli localised in wounds, are absorbed and carried away by the lymphatic and vascular channels and distributed throughout the body. They seem chiefly to affect the cells of the central nervous system. Infection is due to microbes capable of living as saprophytes outside the animal body.
Nicolaïer’s bacillus assumes the form of a straight rod, one end of which is swollen by the presence of a spore. It is anerobic, grows in a number of different media, most rapidly at a temperature of 100° to 102° Fahr. (38° to 39° C.), and stains well by Gram’s method.
Though quite common in the horse, tetanus is rare in other domestic animals.