134
Contagious Pleuro-Pneumonia of Goats
the absence of any evidence of the pneumonia at autopsy in any experimental
animals (apart from those infected by insufflation). In the light of this
finding, it was considered undesirable, rather than otherwise, to maintain
large numbers of healthy goats on hand on premises where the disease did
exist, as tending to increase the possibility of accidental infection.
Preparation of inocula.—The technique for the preparation of inocula
has been as far as possible uniform. It has been found most convenient to
open the thorax laterally on each side. The skin over the thorax is clipped,
the goat killed usually by stunning and bleeding, the skin thoroughly disin-
fected with lysol and reflected dorsally together with the fore-limb. The
ribs are then cut through proximally and distally, and the flap so produced
reflected forwards, exposing the lungs in situ as shown in Plate V. Any effusion
is then collected by aspiration into a sterile flask, and suitable portions of
affected lung excised and transferred to a sterile mincer and minced. The
lung pulp is then mixed with an equal volume of cold Tyrode's solution,
(saline pH 7.4 was used initially, but was later replaced by Tyrode pH 7.4,
which was found more favourable to the survival of the agent—Experiment
19), agitated for a few minutes, strained through fine-mesh wire gauze,
bottled, and transferred to cold storage at 0°— 5°C. till required. Throughout,
all possible sterile precautions were taken.
For collecting the effusion from the local reactions, the technique has
been ordinarily similar to that for the pleuritic effusion. Free incisions are
made into the tissue and the fluid aspirated where it accumulates. It has
sometimes been the practice to aspirate the fluid directly into the syringe,
and inoculate it before coagulation occurs. Any modifications in technique,
and special techniques, are detailed under the heading of their respective
experiments.
In all instances, the material used for inoculation has been either from
animals slaughtered or animals dying during the day, and opened immediately
after death. All material from goats dying overnight has been discarded
for inoculation purposes on account of the risk of anaerobic invasion, and also
of the loss of infectivity.
Sterility and culture.—For purposes of culture it was deemed advisable
to use where possible m dia prepared from goat's flesh, and for blood and
serum-enriched media, goat blood and serum.
For routine tests of the sterility of the pulmonary and local lesions
and with a view to cultivating the etiological agent, the following media
have accordingly been employed : plain agar and broth ; blood agar (rabbit
and goat); serum agar and broth (goat); glucose broth ; Robertson's medium;
and in some instances Soparker's medium, kindly supplied by Dr Pandit,
Director of the King Institute of Preventive Medicine, Madras. These media
have been inoculated either direct from lungs, etc. in situ, or from portions
of lung, or effusion, taken with aseptic precautions, and transferred to sterile
containers for manipulation in the laboratory.
Biological tests.—At the conclusion of all inoculations it has been the
practice to administer a portion of the residue intra-muscularly to at least
two guinea-pigs, and, if sufficient was available usually also to rabbits by
various routes, and sometimes to mice.