Sunday June 26,
2011. I was on duty the whole day
as Dr Vanessa Lin was on leave.
Usually I work from 9.30 am to 11
am on Sundays and Dr Vanessa Lin
starts from 11 am to 5 pm.
BE KIND TO PETS TIPS TO OWNERS
1. Malignant fibrosarcomas in a
2-year-old cat. The young couple
came for a 2nd opinion as the cat
came a few months ago for a right
eye injury. Now the cat had
multiple large firm hard lumps on
the right side of the body mainly
and the right eye is a white
cloudy mass. The first lump
appeared above the right shoulder
blade. Then another one grew
behind it. Today, the right front
leg had a chicken egg's lump under
the armpit (axillary lymph node
metastasis). There were two
smaller lumps to the left side of
the midline near the left shoulder
The owner had consulted Vet 1 who
did the following:
1. Fine needle aspiration sent to
the histopathology lab.
2. Surgical biopsy sent to the
histopathology lab as the fine
needle aspirate was not useful.
Malignant fibrosarcoma was
3. Complete blood cell count
indicated a high white cell count
initially. X-rays were done.
The fibrosarcomas are malignant
and grow aggressively to massive
sizes. Surgical excision of the
axillary lymph node is highly
risky as the cat is not in good
health (very thin now) and the
tumour has spread to the muscles.
The tumour will recur after
Chemotherapy is not well tolerated
by the cat. Radiation therapy is
not available for cats in
Singapore. Therefore, it would be
best to let the cat enjoy the
expected one month of his life
before the tumour ruptures causing
infection and pain and requiring
euthanasia. Also, the right front
paw shows signs of swelling due to
venous obstruction. The cat is
thin and has difficulty walking on
the right front leg.
A malignant fibrosarcoma is a
cancerous growth of the fibrous
connective tissue. It is one of
the most common musculoskeletal
cancers found in cats.
There are four possible causes of
1. Older cats with usually a
single, irregularly shaped mass
found on the trunk, legs & ears.
2. Rare cases said to be vaccine
3. A mutant form of FeLV known as
'feline sarcoma virus' (FeSV).
Usually happen in younger cats &
occurs as multiple tumour masses.
4. Genetics? This has not been
This young cat had the first lump
appearing to the right of the
midline, between the shoulder
blades and had been vaccinated. It
is possible that he could be
suffering from a vaccine induced
sarcoma. Could it be due to
genetics? His right eye ball
is no longer normal. Could it be
the original site of the sarcoma
inside the eyeball ? Could he be
having FeLV too as this was not
tested. It is hard to say.
Cat owners with very small
fast-growing lumps on the
vaccination site or in any area
may need to find a vet that will
remove the lump immediately rather
than do fine needle aspiration and
surgical biopsy as these test
By fast-growing lumps, I mean that
the lump "suddenly appears" or
double in size every week.
Although malignant fibrosarcomas
do recur in cats after surgery,
early radical surgical excision
with a wide margin and repeat
surgeries when the lumps recur
and are small may lead to an
extension of more than one year of
By small lumps, I mean those that
are less than 1 cm in diameter.
Surgical plus chemotherapy prolong
lives but chemotherapy is not well
accepted by the cat. Radiation
therapy has side effects too and
is not available for cats and dogs
in Singapore. Once the
fibrosarcoma has spread, surgery
is not advised as fibrosarcomas
grow very big very fast and do
spread elsewhere in the body.
Prognosis, cost and the welfare of
the cat are important
considerations in the treatment of
fibrosarcomas in the cat. In this
case, the owner opted for no
treatment and asked me how long
the cat would live. I expected one
month of good quality life before
the armpit tumour ruptures and
become infected and painful.
In this young cat, early
radical excision of the sarcoma
and sending the tumour for
histopathology would be my
approach to the treatment of this
case. This approach is to
minimise the chances of metastasis
(spread of the tumour).
The client would be advised that
the fibrosarcoma will recur and
repeat surgeries will be needed.
There have been a report by a vet
of success using this approach but
not much details have been given
as she only encountered 3 cases in
26 years and was successful in
treating 2/3 cases with repeat
From my experience, most pet
owners in Singapore have a
wait-and- see attitude. Only when
the tumour is large will they seek
veterinary advices. By then, the
fibrosarcomas have spread and
BE KIND TO DOGS & CATS --- GET
EYE ULCERS TREATED WITHIN 4
HOURS --- IF YOU DON'T WANT
THEM TO BE BLIND.
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