132
Contagious Pleuro-Pneumonia of Goats
both of the alveoli and of the interlobular septa. The lesion is resiliant to
the touch, usually in continuity with a hepatised area and on incision exudes
clear, straw-coloured fluid, which is highly virulent. The lesion is red in
colour, and histopathologically presents a picture of oedema of the alveoli,
with marked dilatation and congestion of the capillaries of the alveolar walls,
and oedematous infiltration of the inter-alveolar septa. Macroscopically
this infiltration is readily discernible, but is never as gross as in the bovine
disease.
In both the figures in Plate V, this type of lesion is well depicted, in-
volving both the apical and cardiac lobes of both lungs. The septal in-
filtration is particularly clear and the lesion is well contrasted with the true
hepatisation of the diaphragmatic lobe.
With this type of lesion, the method of spread is definitely via the inter-
lobular septa. The septa at the periphery of the lesion are invariably dilated
with lymph and radiate out from the focus of infection well into the surround-
ing healthy lung. The focal type of lesion, however, appears to spread by a
progressive, non-selective involvement of all surrounding healthy lung tissue
and is so spreading in the lungs here depicted.
The usual picture at autopsy is pleurisy with effusion, as described ;
and partial or complete hepatisation of lobes, with varying extension by means
of one or the other of the types of early lesion described. The hepatisation
is either red or grey in colour, but on histological grounds it can be stated
that the traditional ' red hepatisation ', with rupture of capillaries and the
accumulation of erythrocytes in the alveoli, the prelude to ' grey hepatisa-
tion ', does not occur. In no sections has true red hepatisation been observed.
This point is discussed further under ' Histopathology '.
In extensive and late lesions, the main portions are extremely friable
and dry, and the central portions are frankly necrotic. In a few instances,
inextensive but unmistakably specific lesions have been found, undergoing
fibrosis and encapsulation.
The above description is of typical specific lesions. Other lesions which
have been observed have been :
(1) A nodular or diffuse fibrosis, with, in the former, marked contrac-
tion. This has been observed several times (Experiments 1
and 11). In one instance it was in association with multiple
abscesses and in one other, with a marked eosinophilia. The
others have definitely been cases of post-pneumonic fibrosis,
in respect of which no further expression of opinion is justified.
(2) Small areas of collapse, red in colour and involving a few conti-
guous lobules. This type of lesion has been by no means rare,
and in one instance was observed in a three months old in-
contact kid born on the premises in association with a bron-
chiolitis. No success attended attempts at transmission from
any of these lesions, however, and their significance is not
known.
A ' marbled' appearance of the lungs, resembling the typical bovine
lesion, has been observed on very rare occasions only and is in no way charac-
teristic of the caprine disease.
Other lesions.—The mediastinal glands are swollen and oedematous
sometimes congested. The splenomegaly described by other workers has