2
Contagious Pleuropneumonia of Goats
of July, August, October, January and February. Rains generally start in Sind
during the middle of June; parhaps, therefore, the incidence reaches its peak during
July and August due to inclement weather. Viswanathan [1937-38] records that the
greater number of deaths occurred in Madras during the period from July to September.
Districts of Karachi, Sukkur and Larkana are particularly free from the disease; no
explanation can be offered to clear this point as meteorologically and climatically
these districts do not differ much from the adjoining districts Highest incidence has
been recorded in Thatparkar district and next comes Nawabshah. Mortality may be
as high as 60 to 100 per cent. Recovery confers immunity and relapses are never
reported.
SUSCEPTIBILITY
The disease is quite specific for goats. In natural outbreaks it has been seen
that sheep and cattle though grazing together with affected goats do not contract the
disease. Every attempt to transmit the disease to cattle, sheep and the usual
laboratory animals has always failed. Longley [1940] has been able to produce fatal
local reaction in five out of six ewes inoculated intramuscularly with affected muscle
effusion, but he was unable to convey the disease by intranasal insufflation of
pneumonic lung emulsion. Gilbert [1937] reports that the disease is caused by a
filterable virus and is communicable to sheep experimentally as well as in natur al
outbreaks and that sheep are less susceptible than goats. Mettam [1929] reports
specificity of the virus only for goats. The virus found in Palestine must be different
to that found in East Africa and India, as the former is communicable to sheep and
is not specific only for goats as in the case of the latter,
PATHOLOGICAL ANATOMY
Autopsy on 49 affected goats in actual outbreaks and on four experimental goats
was conducted and no difference in the lesions of natural and experimental cases was
found. The post-mortem appearances are very characteristic and are readily recogniz-
able when a few cases have been seen. The presence of pleurisy and pneumonia has
been a constant feature of this disease. The visceral pleura over a pneumonic lesion is
constantly involved. In early and rare cases a small focus of dry pleurisy is seen but
generally there is pleural exudate, which may measure as much as 300 c.c. It is clear,
citron yellow in colour, odourless and free from blood and pus. The exudate readily
coagulates within five minutes of opening the thorax Pneumonia may be bilateral
or unilateral. Incidence of bilateral involvement is 76 per cent and unilateral 25 per
cent. Lobar distribution shows that diaphragmatic lobe is most frequently affected
(87.0 per cent) cardiac lobe is affected to the extent of 75 per cent and a pical lobe
62.5 per cent. Entire lungs involvement comes to 28 per cent. In all the cases,
consolidation of the lungs is observed
The hepatization is either red or grey in
colour and it may be partial or complete, involving one or all the lobes. Two kinds
of lesions are noticed, the focal (Plate I, fig 2) and the diffuse. (Plate II, fig 3). The diffuse
lesion is more common and is highly characteristic; almost invariably involves the apical or
cardiac lobes in part or entirely. The lung is hard and on incision exudes clear,
citron yellow coloured fluid. In the majority of cases the diaphragmatic lobe has been
found to be generally affected and it may be taken that infection invariably starts
from that lobe. In advanced cases the lobes of the lung are found adherent to costal
pleura, diaphragm and heart. In old and extensive cases, portions of the affected lungs
become friable, dry and necrotic. In one experimental goat the lesions were found
to be undergoing fibrosis and encapsulation. The mediastinal lymphatic glands are
usually enlarged and on sectioning somewhat swollen and moist; no enlargement of
spleen and liver has been noticed; pericarditis has been seen in very few cases. No