348              An Outbreak of Equine Encephalomyelitis

The liver was found to be fatty in two cases, while congestion and petechial
haemorrhages were seen in the kidneys in practically all cases. In all cases in
which there was no retention of the urine the bladder was found to be normal,
but in those with any degree of suppression of the urine it was either found to
be enormously distended or shrunken in size to a small volume, with a greatly-
thickened wall due to infiltration with new granulomatous tissue, consequent
on the irritation set up by cystitis. In such cases the bladder contained only
a small quantity of a thick oily urine of an offensive odour and with a quantity
of a thick greenish-coloured sediment composed of precipitated mineral matter
adhering to the mucosa, which on its removal was found to be thickly studded
with haemorrhages.

Exactly similar changes in the bladder had been seen in horse No. 80
which had been attacked in 1935.

The brains and spinal cords of all the animals that were destroyed were
carefully examined but except for a few petechial haemorrhages, here and
there, in the cord and some evidence of softening especially in the lumbar
region not much in the way of naked-eye changes was seen.

                HISTOPATHOLOGICAL CHANGES

Pathological tissues from a number of cases were sent to Mukteswar for
histological examination. The findings were more or less identical in each
case and they may be briefly summarized as follows :—

Spinal cord.—Congestion of the meningeal vessels. Marked gliosis,
especially of the grey matter. Degenerative changes with
perivascular haemorrhages in the grey matter which also showed
some degree of infiltration (glia) around the central canal which
appeared dilated.

Cerebrum.—Congestion of meningeal vessels. Gliosis with micros-
copic haemorrhages, some of which were perivascular. Neuro-
nophagia. Slight cuffing of blood vessels.

Kidney.—Deep congestion. Slight interstitial changes. The tubules
showed early degenerative changes, and even necrosis in places.
The glomeruli were congested, and showed leucocytic infiltra-
tion.

Urinary bladder (in a protracted case with thickening of the wall).—Marked
congestion. The mucous membrane highly petechiated and
hyperplastic with desquamative and necrotic changes on the
free edge. The mucosal surface showed Gram-positive bacteria
and deposit of blood pigment, and in some places the entire
mucosa had been desquamated. A few foci of lymphocytic
infiltration were present in the submucosa.