cat has had successful treatment of skin cancer of the
nose with locally applied radiotherapy
is always extremely difficult when you learn that your cat
has developed cancer. There are often feelings of bewilderment
and even guilt (‘how could I have prevented this?'), and it
inevitably takes time to come to terms with the disease that
is present. For the vast majority of tumours, the underlying
cause is simply unknown, and therefore prevention is impossible.
However, for many (although not all) tumours, once a diagnosis
has been made treatment may be available that will significantly
improve both the quality and length of life for the cat.
is always worth discussing with your veterinary surgeon what
the treatment options are for your cat and the particular
cancer that has been diagnosed. Some treatments are widely
available in general practice, while others are only available
at specialist centres. Depending on what tumour has been diagnosed,
your veterinary surgeon may therefore suggest that your cat
would benefit from being referred to a specialist with expert
knowledge and a greater range of treatment options. By being
referred to a specialist, this may give you further opportunity
to discuss and find out about the cancer and treatment options
available, but in all situations, further tests or treatment
will only be undertaken if you decide to have this
treating cancer, it is important that everyone involved has
the same goals in mind. Veterinary surgeons aim to provide
an improved and good quality of life for the cancer patient
without producing any unacceptable side-effects with treatment.
Ideally this will also mean a longer life, and this is usually
achieved. However, a longer life that ultimately involves
unnecessary suffering and pain has to be avoided. Inevitably
a decision will be needed on whether euthanasia is the best
or most appropriate option. This is a distressing time, and
it helps to have talked in advance with your vet about this,
and to know what guidelines you can judge the quality of life
by. In addition to your vet, having the support of friends
or family can be invaluable.
are three main forms of therapy for cancer – surgery, chemotherapy
(drugs) and radiation therapy. What is used (or offered) for
any individual cancer will depend on many factors, including
the type of cancer, its site in the body, the presence or
absence of metastases (distant spread of the tumour), and
what is available/accessible to you. If you have any doubts
or questions, ask your veterinary surgeon for more information.
for cancer patients
is the single most common form of therapy for cancer and is
the most likely treatment to result in a cure. It can have
several different goals, depending on the circumstances but
a cure (complete removal of the tumour) is not always possible
as some tumours spread readily through tissues, or can spread
to distant sites (metastasise). This is one of the reasons
why an early diagnosis and early treatment can significantly
improve the long-term prognosis. Surgery can therefore have
a number of different goals:
- Obtaining a biopsy (sample of the
tissue) for the initial diagnosis and to determine the type
of cancer present
- Removing all of the cancer present
to effect a cure
- Repeating surgery where the first
attempt failed to remove all of the affected tissue to
effect a cure
- Removal of a large bulk of tumour
with the knowledge that this will not cure the disease
but with the intention to follow this up with additional
therapy (drugs or radiation therapy) to help combat the
remaining cancer. In this way, surgery can significantly
improve the effectiveness of other treatments.
- Removal of the tumour or metastatic
disease (tumour that has spread elsewhere in the body)
where it is known and understood that surgery cannot cure
the condition, but can appreciably improve the quality
itself can inflict some pain and suffering, and inevitably
there are some risks involved with surgery (that vary between
patients). Again, you can discuss with your vet the risks
and benefits anticipated with surgery to help make a decision
in the best interest of your cat. You can also discuss with
your vet any pain relief (analgesic therapy) that can be given
for the surgery and afterwards, and what sort of post-operative
care would be required.
accelerator used for radiotherapy
therapy is a frightening concept for many people as it is
often assumed there will be numerous side-effects associated
its use. However, as with any form of cancer therapy for
cats, the goal is to improve quality of life and to relieve
any discomfort, without causing any unnecessary
additional suffering. Radiation therapy is able to achieve
this for many cat cancers. Unfortunately, the availability
of radiation therapy is quite restricted and so your veterinary
surgeon is likely to have to refer you to a specialist for
therapy most commonly involves what is known as 'external
beam radiation' – similar to X-rays. A machine is used to
focus a beam of radiation at the tumour, but the radiation
is much more intense than that produced by an X-ray machine.
The radiation produced has the ability to kill off cancer
cells, but can also damage normal cells too. Thus by carefully
calculating the dose and the frequency of radiation therapy,
along with focusing the beam of radiation on the cancer being
treated, it is possible to kill off the cancer cells while
causing little damage to surrounding tissues. Although radiation
therapy is used to kill cancer cells, this does not mean that
the treated cat becomes 'radioactive' and there is no risk
whatsoever to people in contact with the cat.
beam radiation therapy requires a short general anaesthetic,
and generally several treatments are given (each lasting only
a few minutes) over a three to five week period. Radiation
therapy has the ability to cure some tumours, while others
can be shrunk and controlled with this therapy for a good
period of time. Although inevitably some damage will occur
to surrounding normal tissue, in most cases this is minimal
and will not cause significant side effects. The specialist
undertaking this therapy would discuss with you in detail
what was involved before you make any decision. The radiation
therapy itself does not hurt, and indeed it can be an effective
way of providing pain relief if the cancer is causing pain.
Skin irritation and hair loss at the site of radiation therapy
is one of the most common side effects – medication will be
used to control this if necessary. Side effects such as nausea
and vomiting are extremely rare. Cats appear to tolerate radiation
therapy better than most animals or humans. They develop less
significant side effects.
form of radiation therapy called brachytherapy is occasionally
used, where sources of radiation are placed within or on the
surface of the body (using a probe) to expose a tumour to
radiation therapy. This can provide a more localised form
of radiation therapy and can be used, for example, to treat
some skin tumours such as squamous cell carcinoma.
on the type of tumour being treated, radiation therapy is
often used in combination with surgery and/or drugs (chemotherapy).
Some forms of chemotherapy will actually enhance the effectiveness
of the radiation therapy.
with radiation therapy, the thought of chemotherapy often
carries many misconceptions. Many people know of friends or
relatives who have received chemotherapy for cancer and have
experienced significant adverse effects associated with the
treatment. Although anti-cancer drugs can, and do on occasions,
produce side effects in animals too, most people are surprised
and relieved at how well cats tolerate chemotherapy. This
is in part because cats tolerate the treatment better and
in part because lower doses are sometimes used to avoid side
effects that affect the quality of life.
wide variety of different drugs are available to treat cancers,
and the choice of drug again depends on the tumours being
treated, what is available, and how the cat may tolerate the
treatment. Your vet will be able to discuss this with you
and if necessary refer you to a specialist for further advice
and/or treatment. For many cancers a combination of drugs
are used so that the dose of any one drug can be minimised
(reducing the risk of side effects) and so that the cancer
cells can be attacked in different ways.
(but not all) chemotherapy drugs work by interfering with
the ability of cells to divide (one of the characteristics
of cancer cells is their uncontrolled, continual growth and
division). Side effects, when they occur, often arise as a
result of interference with other cells in the body that also
divide rapidly, such as cells in the bone marrow, the intestinal
tract and the skin. Side effects that may be seen with chemotherapy
Suppression of the bone marrow - this causes a low white blood
cell count. The cells usually affected first by this are white
blood cells known as neutrophils. Where chemotherapy is being
given that can affect the bone marrow, it is important that
regular blood samples are taken to monitor the white blood
cell count (usually seven to 10 days after the drug is given).
If the neutrophil count falls too low, the dose and/or frequency
of the drug is usually reduced, and antibiotics may be temporarily
prescribed. Platelets (cells in the blood associated with
clotting) may also sometimes be affected by chemotherapy,
and these too are checked when routine blood samples are taken.
Hair loss – although hair loss can be one of the most obvious
side effects of chemotherapy in humans, hair loss in cats
is rare. Where it does occur, it is usually just the whiskers
that are affected and generalised hair loss is extremely rare.
Gastrointestinal irritation – a number of drugs used to treat
cats can cause irritation to the intestinal tract for a few
days after their administration. This can be manifested as
nausea and vomiting, or sometimes just as lethargy and inappetence.
Where this occurs the dose of the drugs can be altered and/or
other medications can be used to overcome these effects. It
is helpful to keep a diary of your cat's behaviour while it
is receiving chemotherapy, including a note of any vomiting
or diarrhoea present, and the cat's appetite. If ever you
are concerned about possible side effects associated with
treatment, contact your vet immediately.
side effects generally depend on the drug being used – some
have the potential to damage the kidneys, or the heart and
thus monitoring or careful use may be required. However, in
general less than 20 per cent (one in five) treated cats will
experience any side effects.
drugs can be given as tablets, but others have to be given
as injections by your vet. Some of these injections need to
be given carefully into a vein (blood vessel) as they can
cause severe irritation to tissues if injected outside a vein.
It is therefore quite common for a catheter to be placed into
a vein (usually in a leg) and for the drug to be injected
through this – for some drugs the injection is a small volume,
but for others it is dissolved in a large volume of fluid
that is infused slowly. Most injectable forms of chemotherapy
are administered at intervals of one to four weeks.
I need to take precautions if my cat is receiving chemotherapy?
anti-cancer drugs can affect healthy as well as cancerous
cells (in humans as well as cats), unnecessary exposure to
these drugs should be avoided wherever possible. This includes
unnecessary handling of the drugs, but also exposure to the
drugs in urine and faeces that are produced by a cat being
treated (and also other body fluids like saliva and vomit).
If some simple precautions are taken, this exposure and any
consequent risks can be reduced to an absolute minimum:
Your vet will warn you if he or she is prescribing tablets
for you to give at home that are potentially harmful. If this
is the case, it is important that these tablets (or capsules)
are not split or crushed – they will have a protective coat
on them that is designed to avoid any direct contact with
the drug itself. Ideally the tablets should be handled and
administered while wearing disposable gloves. If your cat
spits out a tablet, this can be picked up (wearing gloves),
wrapped in kitchen paper and then flushed down the toilet.
Most drugs are eliminated from the body in the urine and/or
faeces, and in general the concentrations of the drug will
be highest in the first few days after treatment. Even here,
the amount of drug excreted is actually very low, but it is
safest to wear disposable gloves when cleaning a litter tray
and to place soiled litter in a sealed bag in the dustbin.
If your cat urinates and defecates outdoors, no special precautions
will be necessary.
Soiled bedding should be washed separately from any other
washing, and similarly food and water bowls should be washed
separately from your own bowls and utensils.
simple precautions will help to make sure that any potential
exposure to these drugs is kept to an absolute minimum.
and palliative care
already noted, it is useful to keep a diary of your cat's
behaviour, appetite, and any abnormalities you observe (vomiting,
retching, diarrhoea, lethargy, etc) as well as a note of when
you administer any medications. This will help you and your
vet determine if any additional treatments or investigations
good nutritional intake is an important part of the supportive
care for your cat with cancer, and offering a variety of foods
can help to ensure that a good appetite is maintained. In
general good quality commercial foods are the best choice
for a cat with cancer, although at times there may be some
special dietary requirements to take into consideration. Warming
the food may also encourage the appetite, but occasionally,
depending on the circumstances, a temporary use of a feeding
tube may be needed to overcome the problems of poor food intake.
Significant inappetence or complete loss of appetite can indicate
an underlying problem such as uncontrolled pain, or side effects
associated with the treatment being received, that requires
further investigation. Your vet will be able to work with
you to try to overcome such problems and provide the optimum
care for your cat.
a good quality of life that is free from pain is the main
goal in managing cats with cancer. Supportive therapy can
be an important part of this, and in addition to the use of
analgesic ('pain-killing') drugs when necessary, other treatments
may also be used (depending on the circumstances) including,
for example, antibiotics where secondary bacterial infection
may be a complication and anti-inflammatory drugs where swelling
and inflammation associated with a tumour is problematic.
be afraid to ask questions and to find out as much information
you can about your cat's cancer and treatment options, and
if there is ever anything you are concerned about regarding
the cancer or potential treatment side effects always contact
your vet immediately.
Updated November 2008