M. Y.
MANGRULKAR
179
the body. In verterinary pathology the subject
becomes more complicated on account of the
unique predisposition of grey horses to melano-
matosis—a point which needs elucidation in
conformity with acceptable opinions on the
subject.
In the collection of nearly 400 tumours at this
Institute, only 13 (3.25 per cent) preserved
specimens of melanomata are present: five from
horses (4.5 per cent of neoplasms of horses),
five from mules (14 per cent of neoplasms of mules)
and three from bullocks (2 per cent of bovine
neoplasms). Relevant information is wanting in
connection with one specimen of each group.
Brief details of the source, location, naked eye and
microscopical characters of these tumours are
given in Table I. It will be realized that, with
such limited material at one's disposal it is not
possible even to attempt to solve any of the prob-
lems associated with the genesis of melanomata. In
this article it is, therefore, proposed only to record
the incidence of the tumour in this country*,
and to give such clinical and microscopical obser-
vations as seem to be of interest. A general
review of available literature on the subject is
also included.
*The incidence has been calculated from the records of
this Institute for the past sixteen years.
TABLE I
A summary of the study of melanomata of animals in the collection of the Institute
Path.
specimen
number
1010/1926
1670/1930
79/1934 .
239/1934 .
266/1937 .
1116/1927
1121/1927
46/1934 .
81/1935 .
232/1935 .
958/1926 .
153/1935 .
194/1937 .
Animal
Mare .
Horse .
Horse .
Horse .
Horse .
Mule .
Mule .
Mule .
Mule .
Mule .
Bullock
Bullock
Bullock
Colour
Grey .
Grey .
? .
Grey .
Grey .
Grey .
Grey .
Grey .
Brown .
? .
Black .
? .
Black and
white.
Age
Aged .
16 years
? .
Aged .
Aged .
8 years .
15 years
18 years
10 years
? .
7 years .
8 years .
5 years .
Location of tumours etc.
Skin of tail and anal re-
gion.
Lower side of tongue .
Ulcerating skin of knee .
Perineal region, head,
neck, sheath (Plate
XIV) and abdominal
cavity.
Perineum and tail .
Prepuce, liver, lung, ?
spleen
Withers, thigh, pleura,
heart, lung, liver, peri-
toneum
Thoracic tumour, affect-
ing lung and peri-
cardium
Between thighs, with ex-
tension to udder
Thigh
.
.
.
.
Skin of chest . .
Scrotum . . .
Pastern. Pedunculated
tumour
Microscopical examina-
tion
Small and large, deeply-
pigmented
Deeply pigmented .
Do. . .
Do. . .
Small and large, deeply
pigmented.
Small and large, superfi-
cial, deep brown to
black tumours in liver
Lightly-pigmented, grape-
like, pleural nodules
Deeply-pigmented .
On udder, scirrhous tis-
with lightly-pigmented
rounded lesions
Deeply-pigmented .
Appearance of " Calcutta
Sore ". Underlying tu-
mour deep-brown.
Deeply-pigmented .
Do. . .
Microscopical
diagnosis
(benign or
malignant)
Benign . .
Benign . .
Benign (Plate
XV, Pig. 1)
Malignant
Benign.
Malignant
Malignant .
Malignant
Malignant (Plate
XV,figs. 2, 3).
Malignant.
Benign. Asso-
ciated
with
filariasis (Plate
XV, fig. 4).
Benign
Benign . .
Remarks
The only tumour
detected and re-
moved. Normal
recovery.
Some gallons of
blood-stained fluid
in
abdominal
cavity
Progressive debi-
lity. Slaughtered
Loss of condition.
Constant blackish
discharge
from
teatsl
Surgically removed
with success
The five cases in horses are from aged grey
animals mostly over 16 years of age. As is
well known, a grey horse with advancing age is
very likely to develop melanomata. In fact, it
is claimed by many that no grey horse, if allowed
to live long enough, will escape melanomatosis.
This high incidence is explained by some as being
due to a gradual loss of pigment (melanin), as the
animal turns from grey to white with advancing
age. Normally, in man and animals, there is a
steady loss of pigment from the skin during the
process of continuous desquamation. In animals
the casting of hairs is an additional factor, involv-
ing loss of melanin. In coloured animals, the de-
mand for the pigment is kept up throughout life.
In the grey horse, however, this demand goes on