Feline mammary gland tumors are the 3rd most common feline tumor and are most commonly diagnosed in middle-aged to older cats. Incidence of mammary tumors is dependent on when cats are spayed. Cats who are spayed prior to 6 months of age have a 91% reduced risk of developing mammary cancer. Spaying after 2 years does not decrease the risk of developing mammary tumors.
Unfortunately, the majority (80-90%) of mammary gland tumors in cats are malignant, and 80-90% will metastasize (spread to other areas of the body) during the course of disease. The most common sites of metastasis include the regional lymph nodes and lungs. Due to the risk for metastasis associated with mammary tumors, thorough staging is recommended prior to any definitive treatment. This would include bloodwork (complete blood count and chemistry panel), urinalysis, aspiration of the regional lymph nodes, chest radiographs and an abdominal ultrasound. Prognosis for patients is dependent on the stage of disease. Stage is based on the size of the tumor (tumors less than 2cm have a better prognosis) and evidence of metastasis (patients that have metastasis typically experience a shorter survival time than those without). Another important factor is whether there is any evidence of invasion into the blood vessels or lymphatics which is determined from the biopsy (cats that do not have any invasion have a better prognosis than those that do).
T Size of Tumor
N Lymph Node Metastasis
M Distant Metastasis
Treatment options include surgery, chemotherapy and supportive care. When
possible, surgery is the recommended first step. Local tumor recurrence is
common if the tumor is incomplete or narrowly excised, so wide surgical margins
(2-3cms and one tissue plane deep) are recommended. This may mean that several
mammary glands are removed at one time (known as a chain mastectomy).
Since most of these tumors will metastasize, chemotherapy may be discussed
to address the risk of the tumor spreading. The most commonly used chemotherapy
agents include doxorubicin (Adriamycin) and carboplatin. Both of these
chemotherapy agents are administered intravenously once every three weeks for a
total of four to six treatments when combined with surgery. In some situations,
chemotherapy may be used without surgery, but the long term prognosis is not as
good when surgery is not performed. Side effects of chemotherapy are typically
mild and resolve on their own within 1-2 days. Chemotherapy side effects may include
lethargy, poor appetite/anorexia, nausea, vomiting, diarrhea, and a decreased
white blood cell count. Doxorubicin can also cause dose cumulative damage to
the kidneys, so bloodwork is performed at each visit to ensure that it is safe
to continue with chemotherapy.
Supportive care may include pain medications, anti-inflammatories and
antibiotics as needed. This can be used with or without other treatment
Mammary gland cancer is not usually a cancer that is curable, but with treatment, can be controlled while maintaining your pet’s good quality of life. Your oncologist will be able to discuss the treatment options, prognosis and help guide you as to the most appropriate plan for your beloved family member. Call us today in Annapolis at (410) 224-0121, Towson at (410) 828-0911 or Columbia at (410) 441-3304.
Lymphoma in dogs is one of the most common canine cancers our animal hospital diagnoses. Lymphoma is a cancer of the lymphocytes, which are a type of white blood cell and a part of the immune system. The function of lymphocytes is to help fight infection, and they can be found in almost any organ in the body, with the most common locations being the lymph nodes, spleen, and bone marrow. When a lymphocyte undergoes a mutation, it grows and multiplies uncontrollably and can cause the lymph nodes, spleen, or any other organ in which it is found to enlarge.
are the Most Common forms of Canine Lymphoma?
There are several forms of lymphoma,
with the most common being multicentric lymphoma. This form of lymphoma is
represented by enlargement of the lymph nodes on the outside and inside of the
body. Other forms of lymphoma include mediastinal (enlarged lymph node in the
chest), cutaneous (skin), extranodal (bone, eyes, liver) and gastrointestinal
(also called alimentary lymphoma). Multicentric lymphoma is by far the most
common and comprises around 80% of diagnosed canine lymphomas, while the other forms
of lymphoma represent about 5% each.
Unfortunately at this time, the cause
for lymphoma is unknown but believed to be multifactorial.
The Clinical Signs of Canine Lymphoma
Our veterinarian specialists often observe these symptoms in patients that may be suffering from lymphoma:
Enlarged lymph nodes. The ones that are usually felt first are the mandibular lymph nodes, located under the jaw.
Decreased appetite and/or energy level.
Coughing or hacking. This is most commonly seen after a patient gets up from sleeping, while eating or drinking, during exercise, or when getting excited. The cough or hack is usually non-productive.
Increased drinking and urination.
Swelling of the face or limbs (known as pitting edema). This occurs when the lymph nodes compress the vessels that normally drain fluid from the limbs or head.
Dry, flaking skin or ulcerative skin
lesions with the cutaneous form of lymphoma. Cutaneous lymphoma can also cause
red lesions in the mouth or loss of pigmentation around the eyes, nose, and
Vomiting and/or diarrhea can be seen
with gastrointestinal or multicentric lymphoma.
Difficulty breathing. This can be seen
with the mediastinal form due to an enlarged lymph node or from fluid
accumulating in the chest (known as pleural effusion).
Diagnosing Your Pet
gold standard for diagnosing multicentric lymphoma at our animal hospital is
performing a biopsy of the lymph node. The larger the biopsy sample, the more
likely we are to obtain a definitive diagnosis, and anesthesia is required to
obtain a biopsy sample. For cutaneous lymphoma, a biopsy is also needed to make
a diagnosis. An alternative, less invasive option is starting with a needle
aspirate of the lymph node (or other affected organ). Unfortunately, a needle
aspirate may not always be able to diagnose lymphoma, so a biopsy or additional
testing on the aspirate sample may be warranted.
Determining the Stage of the Disease
have obtained a diagnosis, staging tests may be recommended to determine the
extent (stage) of disease as well as to ensure that there are no other concerns
that could impact the treatment recommendations.
The Five Stages of Canine Lymphoma
Stage I: One lymph node affected
Stage II: Lymph nodes enlarged either in front of the diaphragm or behind it (front or back half of the body)
Stage III: Lymph nodes enlarged on both sides of the diaphragm
Stage IV: Liver and/or spleen involved
Stage V: Bone marrow, eyes, intestines, skin, lungs (anywhere outside of the lymph nodes, liver and spleen) affected.
Bloodwork with a complete blood count (CBC) and chemistry panel
There are two different forms of lymphoma; B cell and T cell. B cell comprises 70-80% of diagnosed lymphoma cases, while T cell represents 20-30%. Dogs with B cell lymphoma, on average, have a longer median survival time compared to dogs with T cell lymphoma.
Typing of lymphoma can be done on a lymph node biopsy, lymph node aspirate or blood (if there are abnormal lymphocytes in circulation).
The tests that can type lymphoma are: flow cytometry, PARR (PCR for antigen receptor rearrangement) and immunohistochemistry.
Bone marrow aspiration
are a few factors regarding lymphoma, which can decrease a patient’s response
as well as their median survival time (negative prognostic indicators). These
Stage V lymphoma
Substage b. This is when a patient is
symptomatic for their lymphoma. It can include a decreased appetite, lethargy,
vomiting and/or diarrhea.
Substage a is when a patient is
Elevated calcium level (known as
T cell lymphoma
Prior use of long term prednisone as
this can induce a resistance to some of the chemotherapy agents
Treatment for Canine Lymphoma
most effective therapy for most types of lymphoma is chemotherapy. There are
many different chemotherapy protocols available for dogs with multicentric,
cutaneous and gastrointestinal lymphoma. Radiation therapy and/or surgery may
also be recommended for certain types of lymphoma.
With any chemotherapy treatment, the goal is to get a patient into a complete or partial remission. Remission is when the cancer burden decreases. If the cancer becomes undetectable, then it would be considered a complete remission, which is the goal for most types of lymphomas. Partial remission means that the cancer has decreased by at least 50%.
most dogs tolerate chemotherapy well with less than 10% of patients needing to
come into the hospital for supportive care secondary to chemotherapy side
effects. Side effects can include:
Thinning of the fur coat. Unlike
people, dogs do not usually lose their fur when treated with chemotherapy,
although their coat may thin out some. Exceptions include: Poodles, Old English
Sheepdogs and some terriers that can lose all of their fur, but almost all dogs
with have their hair growth resume once chemotherapy is completed.
Stomach upset. This can include a
picky appetite, nausea, vomiting, diarrhea and lethargy. These side effects
most often occur 2-5 days after treatment, but tend to be mild and resolve on
their own with some supportive medications at home within 1-2 days.
Decrease in white blood cell counts.
This is most often seen about a week after treatment. Most dogs are
asymptomatic if their blood counts are low and rarely need to be placed on
antibiotics or require coming into the hospital for evaluation and treatment.
side effects that require a visit to the hospital are considered unacceptable
and may result in a reduction in the dose of the chemotherapy agent vs changing
to a different chemotherapy protocol vs stopping treatment.
may also be clinical trials available across the country which are trying to
find new ways to treat lymphoma and improve our patients’ prognosis. Owners may
want to inquire about this option to see if there are any clinical trials open
and if their pet may be a candidate.
the most common questions after a patient has been diagnosed with lymphoma is
whether or not they can be cured. In very rare instances, dogs are thought to
be cured of their lymphoma by chemotherapy. More often, most patients will
remain in remission for a certain period of time, then fall out of that
remission. This is most often characterized by a recurrence of their original
clinical signs. When this is seen, chemotherapy can be reinstituted and a
second remission achieved, but it is usually of a shorter duration than the
previous one. Eventually, most lymphomas go on to develop a resistance to all
of our chemotherapy drugs, and patients must be euthanized due to a declining
quality of life.
prognosis for lymphoma is dependent on the type of lymphoma as well as the
chosen chemotherapy protocol. Dogs with B cell multicentric lymphoma treated
with a CHOP based protocol have a median survival time of 12-18 months. The
term median implies that 50% of dogs will survive beyond this time point.
The goal with any treatment is to help to improve and maintain a patient’s quality of life. Your oncologist will be able to discuss the treatment options that are available and together you can determine what option is in your pet’s best interest. Call us today in Annapolis at (410) 224-0121, Towson at (410) 828-0911 or Columbia at (410) 441-3304.
Brewster Sanger is a 10-year old Golden Retriever with lymphoma who recently graduated from CHOP (a chemotherapy combination treatment) at our animal hospital! He is a patient of Dr. Silver that we began treating in February of 2019.
What is Lymphoma?
Lymphoma is a type of cancer that stems from white blood
cells called lymphocytes. These cells assist the immune system in
battling infection, and are found in the lymph nodes, bone marrow, and the
spleen. Likewise, lymphoma is commonly found in these parts of the body.
Lymphoma has many variations, but there are four in
particular that are most common in dogs. These include: multicentric,
alimentary, mediastinal, and extranodal. Multicentric lymphoma is the most
common of its type, and affects the lymph nodes.
Symptoms of Multicentric Lymphoma
The primary clinical sign of multicentric lymphoma is swollen lymph nodes, which can be anywhere from three to 10 times their normal size. Other signs include lethargy, weakness, fever, anorexia, and dehydration.
How We Can Diagnose Lymphoma
In addition to an exam and blood work, we will need to perform a fine-needle aspiration of the affected lymph nodes/organ(s). We can also do staging tests to see how far your pet’s condition has progressed. From there, we can walk you through your pet’s treatment options and help you make the best decision for their needs and yours.
The type of treatment your pet receives at our animal
hospital depends on the type of cancer they have and how advanced it is. In the
case of Brewster, we selected a chemotherapy combination known as the CHOP
protocol. Other pets may benefit from radiation therapy, surgery, or a
combination of therapies to give them the best prognosis.