Lymphoma v
Susan A. Kraegel
Lymphoma is a cancer of a specific
white blood cell called the lymphocyte. Lymphocytes are found throughout
the body in blood and tissues and act to protect the body from
infection. Lymphocytes are the major cells found in the lymph nodes or
"glands." In lymphoma, the cancer cells invade and destroy
normal tissues. The most common site for lymphoma is the lymph nodes,
but lymphoma cells, like lymphocytes, can grow anywhere in the body. In
most dogs and cats with lymphoma, the cancer cells are present in
multiple lymph nodes and tissues.
Chemotherapy is the treatment of
choice for almost every dog and cat with lymphoma. Chemotherapy is the
administration of drugs by injection or by mouth to kill cancer cells.
The chemotherapeutic drug circulates throughout the body. This is
important for lymphoma because the cancer cells are in many places at
once. Surgery and radiation therapy are less useful in lymphoma because
these treatment methods attack cancer cells at only one site.
The goal of chemotherapy for animals
with lymphoma is to induce a complete "remission" by killing
most of the cancer cells. "Remission" means that all symptoms
of the cancer have temporarily disappeared. Animals with lymphoma that
are in complete remission look like normal animals by all tests. They do
not have any signs of cancer, and all masses or lumps have disappeared.
They eat, drink, and run just as they did before they developed cancer.
Some of the cancer cells do survive in an animal in complete remission,
but the numbers are too small to detect. Eventually, these few cells
will grow and the cancer will become evident again. When this happens
the animal is said to be "out of remission." Sometimes a
second remission can be achieved with additional chemotherapy.
Eventually, the cancer cells will become resistant or insensitive to all
drugs and cause the dog or cat to die.
Veterinarians use many different drugs
and drug combinations called "protocols" to treat lymphoma in
dogs and cats. No one knows the "best" treatment, and many
protocols give similar results. In general, the longest survival times
are reported for protocols that use a combination of drugs and include
more expensive drugs.
Although chemotherapy does not cure
dogs and cats with lymphoma, in most it does extend the quantity and
quality of life. About 80 to 90 per cent of dogs with lymphoma attain a
complete remission with an average survival of 1 year, and 25 per cent
of dogs live 2 years. For cats, the remission rate is lower, with about
50 per cent attaining a complete remission, but cats who achieve only
partial remission also feel better according to owners. The average
survival for cats is 7 to 10 months.
Veterinarians use chemotherapy to give
dogs and cats with lymphoma a good quality of life with minimal side
effects. Most dogs and cats with lymphoma feel good even though they are
receiving chemotherapy. The potential for side effects does exist,
however, and varies with the protocol used. The most common side effects
include decreased energy, decreased appetite, vomiting, and diarrhea.
Occasionally, more severe side effects occur, and in rare cases an
animal receiving chemotherapy will die as a result of treatment.
Unfortunately, the only way to know whether an animal is going to have a
drug reaction is to give the drug. Some animals never get sick during
chemotherapy, but others are very sensitive to the drugs. If your pet
has a serious reaction, the drugs or doses your pet receives may be
individually adjusted to maintain a good quality of life.
As an owner, you can help your pet
with lymphoma by watching the pet closely after each treatment.
Chemotherapy will suppress your pet’s immune system and make him or
her more susceptible to infections. These infections generally arise
from bacteria that normally live in the intestinal tract and on the
skin, not from the environment. Signs of an infection may include loss
of appetite, vomiting, diarrhea, decreased activity, or depression.
Phone your veterinarian immediately if your pet appears ill while
receiving chemotherapy. These signs are usually only brief reactions to
the drugs, but prompt treatment can often prevent more serious side
effects from developing.
Copyright ©
2000 by W.B. Saunders Company. All rights reserved
