Lymphoma in animals is a
malignant cancer originating from
lymphocytes, which are an important component of the
Lymphoma also occurs in humans. The disease occurs in
bone marrow, and organs such as the
gastrointestinal system. It is also known as lymphosarcoma.
Cytology of lymphoma in a dog
Lymphoma in dogs
Lymphoma is one of the most common malignant
tumors to occur
in dogs. The cause is
but there also suspected environmental factors involved.
Commonly affected breeds
The cancer is classified into low and high
grade types. Classification is also based on location. The four location
types are multicentric,
mediastinal, gastrointestinal, and extranodal (involving the kidney,
central nervous system, skin, heart, or eye). Multicentric lymphoma, the
most common type, is found in the lymph nodes, with or without involvement in
the liver, spleen, or bone marrow. Mediastinal lymphoma occurs in the lymph
nodes in that area and possibly the
Gastrointestinal lymphoma occurs as either a solitary tumor or diffuse invasion
of the stomach or intestines, with or without involvement in the surrounding
lymph nodes, liver or spleen. Classification is further based on involvement of
General symptoms include depression, fever, weight loss, loss of appetite,
Hypercalcemia (high blood
levels) occurs in some cases of lymphoma, and can lead to the above symptoms
plus increased water drinking, increased urination, and
Multicentric lymphoma presents as painless enlargement of the peripheral
lymph nodes. This is seen in areas such as under the jaw, the armpits, the
groin, and behind the knees. Enlargement of the liver and spleen causes the
abdomen to distend. Mediastinal lymphoma can cause fluid to collect around the
lungs, leading to coughing and difficulty breathing. Hypercalcemia is most
commonly associated with this type. Gastrointestinal lymphoma causes vomiting,
melena (digested blood in the stool).
Lymphoma of the skin is an uncommon occurrence. An important type originating
from T-lymphocytes is
mycosis fungoides. It can have a wide variety of appearances, from a single
lump to large areas of bruised,
Symptoms for lymphoma in other sites depend on the location. Central nervous
system involvement can cause
Eye involvement can lead to
bleeding within the eye,
retinal detachment, and blindness. Lymphoma in the bone marrow causes
count, and low
white blood cell count.
affected lymph nodes or organs confirm the diagnosis.
blood analysis, amd bone marrow biopsy reveal other locations of the cancer. The
stage of the disease is important to treatment and
- Stage I - only one lymph node or
lymphoid tissue in one organ involved.
- Stage II - lymph nodes in only one area of the body involved.
- Stage III - generalized lymph node involvement.
- Stage IV - any of the above with liver or spleen involvement.
- Stage V - any of the above with blood or bone marrow involvement.
Each stage is divided into those with systemic symptoms (loss of appetite,
weight loss, etc.) and those without.
Complete cure is rare with lymphoma, but long
times are possible with
chemotherapy. With effective protocols, average first remission times are 6
to 8 months. Second remissions are shorter and harder to accomplish. Average
survival is 9 to 12 months. The most common treatment is a combination of
doxorubicin. Other chemotherapy drugs such as
mitoxantrone are sometimes used in the treatment of lymphoma by themselves
or in substitution for other drugs. In most cases, appropriate treatment
protocols cause few side effects, but white blood cell counts must be monitored.
When cost is a factor, prednisone used alone can improve the symptoms
dramatically, but it does not significantly affect the survival rate. The
average survival times of dogs treated with prednisone and untreated dogs are
both one to two months. Using prednisone alone can cause the cancer to become
resistant to other chemotherapy agents, so it should only be used if there is
definitely no chance of further treatment.
Lymphoma with a
high grade generally respond better to treatment. Dogs with B-lymphocyte tumors
have a longer survival time than T-lymphocyte tumors. Mediastinal lymphoma has a
poorer prognosis than other types. Otherwise, the stage of the disease is the
best prognostic factor.
Lymphoma in cats
Lymphoma in young cats occurs most frequently following infection with
feline leukemia virus (FeLV) or to a lesser degree
feline immunodeficiency virus (FIV). These cats tend to have involvement of
lymph nodes, spine, or mediastinum. Cats with FeLV are 62 times more likely to
develop lymphoma, and cats with both FeLV and FIV are 77 times more likely.
Older cats tend to have gastrointestinal lymphoma without FeLV infection. The
same forms of lymphoma that are found in dogs also occur in cats, but
gastrointestinal is the most common type. Lymphoma of the kidney is the most
common kidney tumor in cats, and lymphoma is also the most common heart tumor.
Symptoms for multicentric, mediastinal, and extranodal lymphoma are similar
to dogs, except hypercalcemia is rare. The most common sites for
gastrointestinal lymphoma are, in decreasing frequency, the
small intestine, the
junction of the ileum,
colon, and the
colon. Symptoms include vomiting, diarrhea, weight loss, loss of appetite, and
tumor can also cause life-threatening blockage of the intestine. Anemia is a
common problem in all cats with lymphoma. Lymphoma of the kidney presents as
bilateral kidney enlargement and failure. Lymphoma of the heart causes
congestive heart failure,
pericardial effusion, and
Diagnosis is similar to dogs, except cats should be tested for FeLV and FIV.
Treatment and prognosis
Chemotherapy is the mainstay of treatment for lymphoma in cats. Most of the
drugs used in dogs are used in cats, but the most common protocol uses
cyclophosphamide, vincristine, and prednisone. The white blood cell count must
be monitored. Remission and survival times are comparable to dogs. Lower stage
lymphoma has a better prognosis. Multicentric lymphoma has a better reponse to
treatment than the gastrointestinal form, but infection with FeLV worsens the
Lymphoma in ferrets
Lymphoma is common in
ferrets and is
the most common cancer in young ferrets. There is some evidence that a
may play a role in the development of lymphoma like in cats. The most commonly
affected tissues are the lymph nodes, spleen, liver, intestine, mediastinum,
bone marrow, lung, and kidney.
In young ferrets, the disease progresses rapidly. Symptoms include loss of
appetite, weight loss, weakness, depression, difficulty breathing, and coughing.
It can also masquerade as a chronic disease such as an upper respiratory
infection or gastrointestinal disease. In older ferrets, lymphoma is usually
chronic and can exhibit no symptoms for years. Symptoms seen are the same as in
young ferrets, plus
splenomegaly, abdominal masses, and peripheral lymph node enlargement.
Diagnosis is through biopsy and x-rays. There may also be an increased
count. Treatment includes surgery for solitary tumors,
splenectomy (when the spleen is very large), and chemotherapy. The most
common protocol uses prednisone, vincristine, and cyclophosphamide. Doxorubicin
is used in some cases. Chemotherapy in relatively healthy ferrets is tolerated
very well, but possible side effects include loss of appetite, depression,
weakness, vomiting, and loss of whiskers. The white blood cell count must be
monitored. Prednisone used alone can work very well for weeks to months, but it
may cause resistance to other chemotherapy agents. Alternative treatments
vitamin C and
Pau d'Arco (a bark extract).
The prognosis for lymphoma in ferrets depends on the their health and the
location of the cancer. Lymphoma in the mediastinum, spleen, skin, and
peripheral lymph nodes has the best prognosis, while lymphoma in the intestine,
liver, abdominal lymph nodes, and bone marrow has the worst.
- Ettinger, Stephen J.;Feldman, Edward C.(1995).Textbook of Veterinary
Internal Medicine(4th ed.). W.B. Saunders Company.
- Hillyer, Elizabeth V.;Quesenberry, Katherin E. (1997). Ferrets,
Rabbits, and Rodents: Clinical Medicine and Surgery (1st ed.). W.B.
- Morrison, Wallace B. (1998). Cancer in Dogs and Cats (1st ed.).
Williams and Wilkins.
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