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Goat Dermatitis. A new Virus Disease of Goats in India
MORBID ANATOMY
The skin lesions previously described are a constant feature. On opening the carcase, typical
lesions can in almost all cases be observed in the alimentary tract, lungs and kidneys. The internal
lesions are essentially similar to those seen on the skin. In the alimentary tract, the abomasum
is almost invariably affected. The duodenum, lips, gum and tongue, oesophagus, large intestine
and rectum are also frequently affected, the frequency being in that order. In these locations the
nodules are greyish-white or yellow in colour and usually smaller in diameter than those seen on the
skin. In the later stages the mucous membrane is desquamated leaving a bright red punched-out
ulcer. The liver is more rarely affected and the lesions present the appearance of in cts. In the
respiratory tract, lesions are as frequent as in the abomasum and are present on the
face of the
trachea and larger bronchi—they have not been seen on the larynx—where they are similar to those
seen on other mucous membranes, and in the lung they are present throughout the tissue as circul r
greyish-white nodules varying greatly in diameter and when they impinge on the surface, the stud-
like appearance of the skin lesion is reproduced. At a later stage the nodules appear to serve as
foci for secondary bacterial infection and the picture becomes that of an ordinary purulent pneumonia.
The kidneys are frequently affected and the lesions appear as white infarcts in the cortical substance.
There is also intense congestion of the medulla. No lesions have been seen in other parts of the urinary
tract. In females, the udder is almost always affected. In early cases there is a general inflam-
mation of the mammary tissue which in later cases gives place to large, white, tough nodes. No
macroscopic changes are visible in the spleen, lymphatic or other glands or in the brain.
Histologically, the skin nodule starts as a proliferation of the cells of the malpighian layer, the
ridges in this layer becoming more accentuated and projecting more deeply into the corium (Plate
VIII, fig. 3). There is at the same time a marked hypertrophy of the individual cells (Plate VIII,
fig. 4) as in fowl-pox, and dilation of the capillaries of the papillae and upper layers of the corium.
There is an infiltration of mononucle and plasma cells in variable numbers with extravasation
of red cells in the deeper layers. Cell necrosis and an increase in the number of infiltrating polymorphs
rapidly occur and finally the nodule is desquamated leaving the muscular layer exposed (Plate VIII,
fig. 5). Staining of skin sections by Goodpasture's method has not revealed distinct inclusion bodies
but some epithelial cells contain red-staining granular material. In the lungs, the lesion (Plate VIII,
fig. 6) likewise starts as a proliferation of the epithelium lining the alveoli or bronchioles, followed
by a monocytic invasion of the area with engorgement of the blood vessels. As there is no sharp
fibrous or inflammatory demarcation between the affected and unaffected areas, bacterial infection,
apparently secondary in nature, soon occurs and the picture becomes that of an ordinary broncho-
pneumonia. Where the lesions impinge on the surface of the lung, the endothelium of the pleura
and its underlying tissue are also affected. In the kidney the cortical lesion is similar to that in
the lung while the medulla is studded with haemorrhages. In the bowel, the lession starts as in
skin and extends to the deeper glandular layers.
TRANSMISSION
As stated, the disease was discovered almost simulateneously during the course of investigating
another goat disease and during experiments on typing of goat-and sheep-pox strains. The former
required serial passages in goats with blood inoculated subcutaneously, and the latter was done
by scarification or intradermal inoculation. A clue thus presented itself that both blood and skin
lesions were infective. Two strains were successfully established by serial passages in goats.
Attempts made at the second generation to infect hill bulls showed these animals to be refractory.
At the fourteenth passage, hill-bulls, sheep, rabbits and guinea-pigs along with control goats were
inoculated, but apart from the goats no other animal was affected. The lesions following scari-
fication have already been described, the only difference in the case of subcutaneous inoculation
being that, in addition to the usual lesions, swelling commences at the seat of inoculation within
24-48 hours and increases slowly to include all the surrounding fascia. On incision, the swelling
is seen to be due to the formation of a yellowish gelatinous exudate. On intravenous inoculation the
incubation period is reduced by one or two days.