Cancer in Dogs

Acute leukemia is a systemic cancer characterized by the infiltration of immature lymphocytes or myelocytes (two types of white blood cells) called in the bone marrow (and commonly in the liver and spleen as well). Patients with acute leukemia are typically quite ill due to their disease. Affected animals are typically young (less than 5 years of age). There is a male gender predilection in some studies.

What causes this type of cancer in dogs and cats?
  • There are no known causes of acute leukemia in veterinary medicine. In people, certain DNA mutations can lead to acute leukemia, but the causes of these mutations are not known. Most cases of acute lymphocytic and myeloid leukemia are not inherited.
What are the common signs of this cancer?
  • Patients will have variable degrees of anemia (low red cell count), thrombocytopenia (low platelet count), and neutropenia (low neutrophil count-a type of white blood cell)
  • Clinical signs in patients with acute leukemia are usually severe due to the level of bone marrow suppression
  • Affected dogs and cats typically have a history of weight loss, excessive drinking and urination, loss of appetite, and lethargy
  • Findings on physical examination can include signs of hemorrhage (bleeding), enlargement of the spleen and liver, and lymph node enlargement
How is it diagnosed?
  • CBC (with pathology review)/chemistry panel/urinalysis
  • 3 view thoracic radiographs
  • Abdominal ultrasound
  • Bone marrow aspirate/evaluation
  • Immunophenotyping via flow cytometry—a test that allows veterinarians to evaluate the exact type of white blood cells that are in the blood or bone marrow. This test may be beneficial in distinguishing acute myelogenous leukemia from acute lymphoblastic leukemia from stage V lymphoma, although sometimes telling the difference between these conditions can be very difficult.
How is this cancer treated?
  • Patients with acute leukemia require aggressive therapy
  • Aggressive chemotherapy with a multi-agent IV chemotherapy protocol is the treatment of choice
  • The specific chemotherapy protocol will be based on the results of the immunophenotype (which tells us the type of white blood cell).
  • Patients may also require intense supportive therapy with treatments such as blood transfusions, broad spectrum antibiotic therapy, IV fluid therapy,  and nutritional support
  •  In-depth monitoring is also required to monitor for signs of infection, signs of bleeding, and signs of abnormal clot formation or DIC (disseminated intravascular coagulation)
What is the prognosis for dogs and cats with this cancer?
  • Prognosis of acute leukemia is typically poorer than with lymphoma
  • Survival times for those dogs that respond to treatment are around 6 months with some dogs living many more months
  •  If the patient does not respond to therapy, survival time is usually weeks as infection and bleeding problems are very common with this disease.
What is on the horizon for this cancer?
  • Bone marrow transplantation is currently the state-of-the-art for the treatment of this disease in people and veterinary oncologists are actively trying to adapt it for dogs.

Appendicular osteosarcoma (bone cancer of the leg) is most common in giant and large breed dogs, with an average age of onset of 7 years. The most common site for the development of osteosarcoma (OSA) is the distal radius (near the wrist), followed by the proximal humerus (near the shoulder) and less commonly proximal and distal femur and tibia (hips to ankles). While acute lameness due to pathologic fracture (disease-related bone break) occurs in some dogs, most present with a history of progressive lameness over several weeks.

What causes this type of cancer in dogs and cats?
  • The cause of this group of diseases is largely unknown
What are the common signs of this cancer?
  • Limping or lameness is the most common sign of this disease
  • A swelling can also be seen at the site of the cancer and this swelling may be painful
How is it diagnosed?
  • The hallmark radiographic (x-ray) changes of bone cancer are destruction of the bone in conjunction with abnormal bone proliferation (growth). There may be varying degrees of changes to the tissue surrounding the bone.
  • Chest radiographs (3 views) are recommended prior to surgery to rule out metastatic (spread) disease in the lungs. Less than 10% of dogs have radiographic evidence of pulmonary metastasis (spread to the lungs) at the time of presentation but >90% have unseen micro-metastasis (cancer that has spread but is so small that you cannot see it on radiographs (x-rays).
  •  Bone biopsy may be performed prior to starting treatment to confirm the diagnosis. Surgery can also be performed without first doing a bone biopsy as most dogs with OSA are very painful and have “classic” radiographic changes on the leg.  The pros and cons of both approaches are discussed in detail with owners.
How is this cancer treated?
  • Amputation remains the treatment of choice to alleviate pain, improve quality of life and control the primary tumor. In our experience, greater than 95% of pet owners report good to excellent quality of life following leg amputation. Severe arthritis of the other legs may prevent an amputation from being considered—therefore a thorough orthopedic evaluation is recommended prior to amputation of the affected limb.
  • Limb or leg sparing surgery remains an important option for giant breed dogs with OSA of the distal radius. Good to excellent leg function is reported by 80% of pet owners.

 

Will chemotherapy be recommended?

  • Cisplatin, carboplatin and doxorubicin (adriamycin) have all shown benefit in the treatment of appendicular OSA. Chemotherapy is initiated as soon as the patient’s amputation or limb spare site is healed, typically 10-14 days after surgery.
  • Carboplatin is a newer platinum based drug that is replacing cisplatin in popularity due to easier administration and decreased side effects.  Carboplatin is the platinum drug of choice at our hospital.  It is well tolerated with minimal gastrointestinal side effects (vomiting, loss of appetite and diarrhea). Myelosuppression (bone marrow suppression) is the major dose limiting toxicity, with the peak occurring 7-14 days after administration. At least 4 treatments, administered at 3-week intervals, are recommended.
  • Doxorubicin can be used as an alternative to the platinum based drugs or as part of a chemotherapy protocol in addition to them.
  • NSAIDS are also recommended in conjunction with chemotherapy.
  • Dogs diagnosed with metastatic disease (cancer that has spread to the lungs or other bones) have an average survival time of 2-3 months. Chemotherapy can be used in this setting to try and slow down the disease progression.

 

Are there other treatment options to control pain?

  • Radiation therapy and/or the use of non-steroidal anti-inflammatory medications (NSAIDs) and/or the use of bisphosphonates can be used to reduce bone pain and improve quality of life when the pet owner decides against surgery.  Chemotherapy can be used in conjunction with any of the above.
  • Radiation therapy is a very effective bone pain reliever. Typically, palliative RT consists of 1-4 treatments administered 1 week apart.  Pain is controlled for approximately 3-4 months.
What is the prognosis for dogs and cats with this cancer?
  • The average survival time after surgery and chemotherapy is 12 months with 20% of patients surviving >2 years.
  •  Most dogs that are treated handle the therapy (both surgery and chemotherapy) very well.
What is on the horizon for this cancer?
  • Palladia, a new targeted chemotherapy, has activity against osteosarcoma in dogs. Studies are currently underway to determine how best to use this drug in the treatment of bone cancer in dogs.
  • Other targeted therapies are being developed that may be very effective in the therapy of this disease.
  • Prosthetic limbs for dogs are also being developed.

Lymphoma and lymphosarcoma (LSA) are interchangeable terms. Lymphoma in dogs is very similar to non-Hodgkin's lymphoma in people. Lymphoma represents 7% of all cancers in dogs. Most affected dogs are between 5-9 years of age, but the disease can occur in dogs of any age. Generalized lymphadenopathy (lymph node enlargement) in an otherwise healthy dog is the most common presentation. Hypercalcemia (high blood calcium) occurs in 20% of dogs with lymphoma. Administration of glucocorticoids (steroids) prior to confirming a diagnosis can make obtaining the diagnosis much more difficult and lead to the cancer becoming chemotherapy resistant.

What causes this type of cancer in dogs and cats?
  • The cause of this group of diseases is largely unknown
What are the common signs of this cancer?
  • Generalized lymph node enlargement in an otherwise healthy dog is the most common presentation of LSA. This lymph node enlargement is non-painful and the dogs generally are feeling well. This clinical presentation is referred to as stage IIIa LSA. Clinical signs will vary depending on the stage of disease, volume of tumor and anatomic location of the lymphoma. Clinical signs are typically non-specific and may include lethargy, weight loss and loss of appetite. If the patient has associated hypercalcemia, clinical signs will include polydipsia and polyuria (frequent drinking and urination). Other symptoms reflect the anatomic location of the lymphoma. Lymphoma of the gastrointestinal system generally results in vomiting and/or diarrhea whereas cranial mediastinal lymphoma results in dyspnea (difficulty breathing).
How is it diagnosed?
  • A thorough physical examination is the most important part of the work-up. This dictates what diagnostic tests will be required to confirm the diagnosis and accurately determine the patient's health status. The diagnostic work-up should always include a complete blood count (CBC), platelet count, biochemical profile, urinalysis and fine needle aspirate (cytology) or biopsy of the lymph node. These tests allow us to confirm the diagnosis, determine if the patient is hypercalcemic, assess kidney function, and determine if the patient has normal blood counts so that we can safely initiate chemotherapy.
  • A lymph node biopsy is used to confirm the diagnosis if cytology is not conclusive or if the type of lymphoma requires biopsy for diagnosis (low grade lymphoma for example). Lymph node biopsy has the added advantage of classifying the LSA, which provides some additional prognostic information.
  • We also recommend performing a flow cytometry test to determine if the patient has B-cell or T-cell LSA.  This test can be performed on a lymph node aspirate.  Knowing whether a patient has B vs T cell LSA is important as it allows us to choose the best chemotherapy protocol for the patient as well as giving us prognostic information.
  • A DNA analysis test called PARR performed from a lymph node aspirate can also be helpful to confirm a diagnosis in most cases.
  • Additional diagnostic tests are recommended to complete the staging (to determine where the LSA is present in the patient’s body. These tests may include chest and abdominal radiographs, abdominal ultrasound and ultrasound guided aspirates of the liver and spleen for cytologic evaluation, and a bone marrow aspirate.
How is this cancer treated?
  • Multi-drug protocol : Treatment consists of the use of several chemotherapy drugs depending on if the patient has B or T cell LSA.  For B-cell LSA a CHOP protocol is used (prednisone, L-asparaginase [elspar], vincristine, cyclophosphamide [cytoxan] and doxorubicin [adriamycin]). Weekly chemotherapy treatments are given for approximately 6 weeks. The treatments are then spaced to every 2 weeks and then to every 3 weeks to complete a total of 6-12 months of treatment. For T-cell LSA a MOPP protocol is used (Mustargen, Vincristine, Procarbazine, Prednisone).  This protocol consists of a 2 weeks on/2 weeks off schedule for chemotherapy for a total of 6-12 months of treatment.  The average survival time for patients with stage IIIa or IVa lymphoma treated with these protocols is 1-1.5 years.
  • Single agent IV chemotherapy protocol using Doxorubicin alone : The patient is treated with a total of 5 treatments of doxorubicin at 3-week intervals. The average survival time with this approach is 9-11 months.
  • Single agent oral chemotherapy protocol using CCNU:  The patient is treated with oral CCNU every 3 weeks.  The median survival time with this protocol is 4-5 months.
  • Prednisone alone : This medication is a steroid and can be given in pill form daily at home. The average survival time for patients with lymphoma treated with prednisone alone is 60 days.

 

How well do dogs tolerate chemotherapy?

  • Fortunately, most dogs tolerate chemotherapy extremely well. At our hospital, 80-85% of pet owners report that their pets' quality of life is good to excellent while on treatment. 80-85% of patients experience no or minimal side effects from the chemotherapy.  If side effects do occur they are usually in the form of decreased energy, decreased appetite, nausea/vomiting, or diarrhea (all of which can be mitigated with supportive medications and protocol adjustments).  Approximately, 5-10% of dogs will have more severe or potentially life threatening side effects, generally dehydration from vomiting and diarrhea or risk of infection from a low WBC count. These patients require hospitalization and appropriate therapy to recover. Chemotherapy protocol adjustments are made for these patients once they have recovered.
  • Because lymphoma is typically not a curable cancer, it is critical that the patient's quality of life is good the vast majority of time. Acceptable side effects may include short-term (1-2 days) loss of appetite, vomiting, diarrhea and listlessness. The patient should quickly bounce back to normal.  Some patients will require a dose adjustment after their first chemotherapy treatment or require anti-nausea or anti-diarrhea medication to reduce the duration of side effects.
What is the prognosis for dogs and cats with this cancer?
  • Most dogs with lymphoma develop medium to high-grade lymphoma that is very responsive to chemotherapy. Greater than 75% of dogs with lymphoma are expected to achieve a complete remission with chemotherapy. The duration of the first remission is variable, depending on the chemotherapy protocol used, with median remission times varying from 6 months to 18 months. The second remission is more difficult to achieve, with approximately 40% of dogs with lymphoma achieving complete remission with a second course of chemotherapy. Less than 20% of dogs with lymphoma will achieve a third complete remission. Approximately 40-45% of dogs with lymphoma live one year with treatment. Approximately 20% of dogs with lymphoma live 2 years with treatment. Without treatment, the average survival time of dogs is one month from the time of diagnosis. This is difficult for many pet owners to believe because their dog often appears to be quite healthy at the time of diagnosis.
What is on the horizon for this cancer?
  • Bone marrow transplantation is currently available and is being used more and more frequently to try and cure dogs with lymphoma. This therapy may hold the promise for long term remissions and cures for dogs and cats in the future as it becomes more available .
  • Diagnostic tests are currently being developed to try and allow veterinarians to diagnose lymphoma at an earlier stage and detect dogs coming out of remission at an earlier time.

Mammary tumors (breast cancers) are the most commonly diagnosed tumor in intact female dogs older than 7 years of age. Male dogs can also develop mammary tumors, but rarely. Several breeds are prone to developing mammary cancer including Poodles, English Spaniels, English Setters, and Terriers. About 50% of mammary tumors are malignant (invasive to surrounding tissue with a high risk of spreading) and 50% are benign—this is very similar to the statistics for breast cancer in women.

What causes this type of cancer in dogs and cats?
  • A hereditary genetic component (which has been found in humans with breast cancer) has not been established as a risk factor for canine mammary cancer.
  • Hormonal influences have been found to be involved in the development of canine mammary cancer. In fact, it has been well documented that spaying (ovariohysterectomy) before the first heat cycle (typically before 6 months of age) dramatically decreases the risk of developing mammary tumors to a less than 1% risk. If spayed after the first heat cycle, the risk of getting mammary cancer increases to 8%. The risk increases to 26% if a dog is spayed after the third heat cycle.
What are the common signs of this cancer?
  • Many owners will notice a lump somewhere along the mammary chain on their dog. The 4th and 5th mammary glands (closest to the groin or inguinal region) are most commonly affected. These masses can be red, purple, or fleshy in color. They can be either soft or hard and sometimes ulcerated. Many dogs have multiple masses present at one time.
  • One of the more aggressive types of mammary cancers (called inflammatory carcinoma) can make a dog’s entire mammary chain very inflamed, ulcerated, and painful. These tumors are very rare.
How is it diagnosed?
  • The best way to diagnose a malignant mammary tumor (as well as determine the type of mammary tumor) is with a biopsy. Needle aspirates (cytology) can be used to rule out other lesions, such as mast cell tumors or benign cysts, but typically cannot definitively diagnose mammary tumors.
  • There are many different types of mammary tumors; each can behave in a biologically different manner (in regards to aggressiveness-risk of spreading or recurring). These include carcinomas, sarcomas, and carcinosarcomas. Most mammary tumors in dogs are classified as carcinomas.
  • It is important to perform blood work to evaluate a dogs’ general heath status.
  • Radiographs are useful in evaluating for spread of these tumors to the lungs.
  • Abdominal ultrasound can be used to look for spread of the cancer to the internal abdominal organs.
How is this cancer treated?
  • Surgery is the treatment of choice for all dogs with mammary gland tumors. The type of surgery performed depends on the extent of disease. Veterinarians try to remove the tumor along with a large zone (about 2-3cm) of normal surrounding skin, fat, and sometimes muscle to reduce the risk of local tumor recurrence. If only one or two tumors are present, removal of just those tumors is typically adequate. If there are multiple tumors present, a more aggressive surgery  (removal of an entire chain, or both chains, of mammary glands) may be recommended.
  • Will chemotherapy be recommended to treat my dog?
  • Chemotherapy may be recommended as part of your dog’s treatment for mammary cancer if the tumor is of a high grade (determined when the sample is evaluated microscopically by a pathologist), aggressive tumor type, is very invasive and unable to be completely surgically removed, or there is metastatic disease (spread to other organs or lymph nodes). The chemotherapy protocols used to treat dogs with mammary cancer are typically very well tolerated.

 

Will radiation therapy be recommended? Radiation therapy may be recommended for certain types of mammary cancers. This treatment is not as routinely used in veterinary oncology as it is for the treatment of breast cancer in people.

What is the prognosis for dogs and cats with this cancer?
  • The average survival time for dogs with mammary tumors is variable and depends on several factors including the grade of the tumor (obtained on the biopsy report after surgery), tumor type, the presence of metastatic disease, and whether there is invasion of the tumor into the lymphatics or blood vessels as well as what treatment regimens are used.
  • The average survival times range from less than a month (for aggressive inflammatory carcinomas) to several years.
What is on the horizon for this cancer?
  • As in women, the use of targeted therapies like Herceptin—a treatment that targets certain molecular and genetic defects found in cancer cells-- holds great promise for improving the outcome of therapy for the treatment of mammary cancer. In veterinary medicine there are currently two targeted therapies-Palladia and Masivet.  There is currently a great deal of research looking for targeted therapies.

Mast cell tumors (MCT) are the most common malignant skin tumors in dogs and among the most common tumors overall. MCT most commonly occur as solitary lumps or masses in the skin and occasionally dogs can have multiple MCTs. These tumors can have a very variable appearance---they can resemble fatty (lipomatous) masses or may be reddened (erythematous) and / or ulcerated. MCT may change size quickly, often waxing and waning in size  (become larger then smaller). They do this because mast cells contain granules of histamine, heparin and other chemicals that when released into the body can cause swelling, redness, and increased stomach acid production.

What causes this type of cancer in dogs and cats?

N/A

What are the common signs of this cancer?
  • A skin mass that gets red after touching it
  • A swelling in the skin that changes size (gets larger and smaller)
  • These tumors can range in size from a millimeter to a few centimeters
  • Sometimes, although not always, the dog may scratch at the skin mass due to it being itchy (pruritic).
  • In severe or systemic cases vomiting, anorexia (loss of appetite), and diarrhea may occur due to the release of certain chemicals in the mast cells.
How is it diagnosed?
  • The first step in making this diagnosis is with a fine needle aspirate and cytology. A small needle is placed in the mass and a few cells are aspirated (removed) from the tumor, put on a slide and then stained. Cytology can be performed at most veterinary hospitals or the slide may be sent to a pathologist for an expert opinion.
  • A biopsy or removal of the mass may be needed for an accurate diagnosis in some cases. Grading the tumor requires a biopsy. MCT can be grade I (low grade), grade II, or grade III (high grade) tumors.
  • Lymph node aspirate, abdominal ultrasound, and chest radiographs are often recommended –to determine the stage of the MCT (where the tumor is or isn’t in the body) and sometimes a bone marrow aspirate is recommended.
How is this cancer treated?
  • Surgical removal is usually the first step in therapy. If the MCT is a low-grade tumor (grade I and some grade II), resections with complete margins are often curative.
  • If complete and wide margins cannot be obtained surgically, radiation therapy (after removing as much of the tumor as possible) is incredibly effective in treating these tumors, with over 80% of these dogs being cured in most situations.
  • If the tumor is a higher grade or one that has already spread, a combination of chemotherapy and / or radiation therapy will often be recommended. The outcomes are often quite good.
  • Targeted chemotherapy-Palladia and Kinavet—are also used effectively to treat mast cell tumors in dogs. These are both oral medications that can be given at home.

 

What role does surgery have in the treatment of MCT?

  • MCT are notorious for their invasive nature into surrounding tissue and tendency to extend far beyond visible margins. If at least 1-3cm surgical margins, both lateral and deep, are not obtained then the probability is high that the tumor will not be adequately excised. While it may be difficult to remove 3cm deep margins in a patient without much body fat, removing a layer of muscle below the tumor is advised. Typically, a surgical margin of a couple of millimeters is not adequate. When surgical margins are close, a second surgery should be recommended as soon as possible.
  • It is important to remember that it is impossible to comment on the completeness of a surgical excision and predict biologic behavior (how aggressively the tumor will act) of MCT without histopathologic (tissue biopsy) evaluation of the entire tumor.

 

Is radiation therapy an option for my dog?

  • Depending on where the tumor is located, it may not be possible to obtain 3cm clean surgical margins. In those cases, it is appropriate to perform a debulking (removing as much as possible) surgery followed immediately by radiation therapy.
  • Mast cell tumors are generally very sensitive to radiation. Radiation is most effective at achieving long-term (greater than 5 years) tumor control when it is delivered to microscopic disease, grade 2 (intermediate) or lower tumor, and in a well-defined radiation field. Radiation therapy can be used to control local disease after incomplete resection of high-grade 2 or grade 3 MCT.

 

When is chemotherapy recommended for MCT therapy?

  • As with any cancer, chemotherapy for the treatment of MCT is most effective when combined with other treatment modalities or used early in the course of disease. Chemotherapy is less effective in treating patients with large tumors versus patients with microscopic disease.
  • Chemotherapy is appropriate when tumor cells extend to the surgical margins and a second surgery and radiation therapy are not feasible treatment options. Chemotherapy is recommended in all cases with lymph node or distant metastasis (i.e. liver, spleen, bone marrow) involvement. It is also recommended for all patients with high-grade II or grade III MCT, even with the tumor is excised with wide margins. 
  • Vinblastine and cyclophosphamide are the drugs we most commonly used
  • Prednisone, Pepcid, and diphenhydramine (Benadryl) are also used to control some of the signs that occur secondary to histamine release from the mast cells.
  • Targeted chemotherapy, using drugs that target certain molecular or genetic abnormalities found more frequently in certain tumor cells, is being used more and more frequently. Palladia, and Kinavet—both targeted chemotherapies have been approved for treating certain mast cell tumors in dogs.
What is the prognosis for dogs and cats with this cancer?
  • The average survival time after surgery depends heavily on the grade of the tumor. Grade I tumors can be cured with surgery, while higher grade tumors –grade II and III tumors –treated with good local control (surgery +/- radiation therapy) in conjunction with systemic therapy (chemotherapy or targeted therapy) often survive for more than 2-3 years.
  • Most dogs that are treated handle the therapy (surgery, radiation and chemotherapy) very well .
What is on the horizon for this cancer?
  • Other targeted therapies are being developed that may be very effective in the therapy of this disease
  • The combination of targeted therapies with traditional chemotherapy is also something that is being investigated

Urinary bladder cancers are more common in female dogs, with Scottish Terrriers, West Highland White Terriers, Shetland Sheepdogs, and Beagles being overrepresented. Transitional cell carcinoma (TCC) is by far the most common type of bladder neoplasia (cancer) encountered in dogs.

What causes this type of cancer in dogs and cats?
  • In people smoking is the single greatest risk factor for the development of bladder cancer. Exposure to certain chemicals (aromatic amines, chemicals used in the dye industry, and chemicals used in textiles, hair coloring, paints and printing) has a greater risk of bladder cancer than the general population.
What are the common signs of this cancer?
  • The most common presenting signs are hematuria (blood in the urine), dysuria (straining to urinate), pollakiuria (frequent urination), and weight loss. On physical examination, a mass may be felt in the abdomen or detected on rectal examination along the urethra. Prostatomegaly (enlarged prostate), abdominal pain, or a distended (large and firm) urinary bladder may be noticed. Rarely, lameness
How is it diagnosed?
  • The Bladder Tumor Antigen test may be useful as a screening test in middle aged dogs (especially in breeds that are predisposed to getting this type of cancer). This urine test is most helpful when there are no signs present; it is a very good screening test. This means that if the test is negative, it is very unlikely your dog has this cancer. However, a positive test requires additional diagnostics to confirm a diagnosis of bladder cancer.
  • Abdominal ultrasound is helpful in evaluating the bladder wall as well as the regional lymph nodes for the presence of a mass or thickened bladder wall
  • Contrast cystography is a test that can detect a filling defect (mass) in 96% of patients affected by bladder cancers. A contrast cystography is an x-ray study of the bladder in which a contrast agent or air is injected into the bladder.
  • Cystoscopy (camera inserted into the bladder) provides a minimally invasive method to directly visualize the tumor and obtain samples for biopsy and culture in female dogs.
  • Obtaining a diagnosis of this type of cancer typically involves getting a sample of the tumor. This can be achieved by either a surgical biopsy (not appropriate for all patients) or cytologic evaluation. Cytologic evaluation involves passing a urinary catheter into the bladder and gently rubbing the tip of the catheter along the tumor to extract some of the cells for analysis.  Cystocentesis (bladder puncture) should never be performed to obtain a cytologic sample or urine sample in patients suspected of having a bladder tumor due to the potential of tumor seeding (tumor growth on the skin or in the abdomen at the site of the cystocentesis)
  • The incidence of spread (metastasis) to the lymph nodes near the bladder in one study was reported to be 39% at initial diagnosis and 48% at autopsy. Chest x-rays have been noted to be positive for spread to the lungs in 17% of patients at the time of initial diagnosis.
How is this cancer treated?
  • There have been several chemotherapeutic agents utilized to effectively treat this cancer. Studies suggest that mitoxantrone or vinblastine (both injectable chemotherapy agents) combined with piroxicam (or Deramaxx or Metacam) (anti-inflammatory agents) may increase both quality and quantity of life.
  • Piroxicam (Feldene) is a non-steroidal anti-inflammatory agent (NSAID) that has been shown to help animals feel better –have less blood in the urine, strain less and urinate less frequently---and allow them to live longer. In some patients, long term use even may result in the tumor getting smaller.
  • Surgery may be an option for your dog, depending on the location of the tumor. Surgery is most appropriate for dogs with early stages of urinary bladder cancers (small tumors) in the apex or body of the bladder. If the tumor is in the trigone (area of the bladder that empties into the urethra), urethra, or both urinary bladder and urethra, surgery is more difficult. Both urethral and ureteral stents can be placed in animals with advanced stages of disease to help relieve discomfort associated with a urinary tract obstruction or to relieve an obstruction preventing urine from reaching the bladder from the kidney. These stents can prolong a good quality of life for quite a long time.
  • Laser therapy is also available as a means of locally controlling the cancer and is quite effective in many dogs in relieving the clinical signs (straining to urinate and increased frequency of urination) for quite a long time
  • Full course radiation therapy (15-18 treatments) is a very effective treatment for local control, however, scarring of the bladder that results can have significant negative impact on quality of life. Palliative (pain-relieving) radiation is well tolerated and may significantly, but temporarily, improve symptoms.
  • Intravesicular therapy (treatment directly into the urinary bladder) can be used but its effectiveness in veterinary medicine is currently unknown.
What is the prognosis for dogs and cats with this cancer?
  • Dogs that are untreated may only survive for a few months, the addition of piroxicam alone can help improve both quality and quantity of life for around 9 months while the addition of an injectable chemotherapy (mitoxantrone or vinblastine) can extend quality of life for an additional 3-6 months. The use of either surgical stents (urethral and/or ureteral) or laser therapy can extend quality of life an additional 5-7 months.
What is on the horizon for this cancer?
  • The use of intra-arterial chemotherapy (chemotherapy delivered directly into the artery that supplies the tumor with blood) through a small surgically placed catheter is being evaluated as a way to deliver higher doses of chemotherapy to the bladder tumor without causing side effects to the rest of the dog.

Chronic Lymphocytic leukemia (CLL) is a condition in which mature (i.e., "normal"-looking) lymphocytes (a type of white blood cell) accumulate in the body (including in the bone marrow and spleen). This results in elevated circulating lymphocyte counts on CBC blood tests. CLL typically occurs in middle age to older dogs and is often found "accidentally" when blood work is being performed for other reasons. CLL usually progresses slowly and patients can typically be medically managed and live well for years.

What causes this type of cancer in dogs and cats?

The causes of CLL in dogs, cats or people are unknown. We do know that something happens to the DNA of the cells that make these blood cells.

What are the common signs of this cancer?
  • Most patients with CLL are asymptomatic
  • If symptoms are present they are typically vague signs of lethargy (decreased energy), decreased activity, or decreased appetite
  • Mild lymphadenopathy (lymph node enlargement) and splenomegaly (enlargement of the spleen) can also be seen
  • Some patients will have a mild anemia (low red blood cell count) and/or thrombocytopenia (low platelet count) along with varying degrees of a lymphocytosis (too many lymphocytes in the blood).
How is it diagnosed?
  • CBC (with pathology review)/chemistry panel/urinalysis
  • 3  view chest radiographs
  • Abdominal  ultrasound
  • Bone marrow aspirate/evaluation
  • Immunophenotyping via flow cytometry of the blood to determine lymphocyte subset (T-cell vs B-cell) .

** The diagnosis is typically confirmed with a bone marrow aspiration.

How is this cancer treated?
  • Treatment is usually in the form of oral chemotherapy with prednisone and chlorambucil (Leukeran)
  • Periodic monitoring of blood cell counts and physical examinations are required
  • In some cases dogs may require stronger treatment such as intravenous chemotherapy either to help induce a remission or in cases where the patient is no longer responding to the oral therapy.
What is the prognosis for dogs and cats with this cancer?

Even though complete remissions are usually not achieved, prognosis with therapy is good with median survival times ranging from 1-3 years. These animals typically have a great quality of life.

What is on the horizon for this cancer?

Targeted therapies are increasingly being used to treat various malignancies and some of these oral drugs are being investigated as a treatment for this disease. As bone marrow transplantation becomes more available, it may become an important treatment for this disease.

The most common tumor of the spleen in dogs is hemangiosarcoma (HSA). Up to 50% of dogs with splenic HSA are in DIC (disseminated intravascular coagulation or inability to clot blood) at the time of presentation. Unfortunately, with surgery alone, the average survival times are only around 3 months. Liver biopsy is essential to differentiate between liver metastasis (spread) and benign hyperplasia (increased tissue growth).  HSA does not always start in the liver or spleen; it can also start in the skin, subcutaneous tissue or the heart. Stage I cutaneous HSA may be cured with aggressive surgical resection. Radiographs (x-rays) of the lungs are required to rule out pulmonary metastasis (tumors in the lungs). Cardiac HSA is a common cause of pericardial effusion (fluid surrounding the heart) in dogs. HSA in cats is rare but occurs most commonly within the abdomen (spleen, liver or kidneys) or subcutaneous tissue (under the skin)

What causes this type of cancer in dogs and cats?

N/A

What are the common signs of this cancer?
  • Many animals present to the veterinarian for bleeding into the abdomen. These animals can have bouts of waxing and waning weakness as the bleeding starts, stops and gets reabsorbed by the dog. Pale gums are often one of the signs of bleeding.
  • Sometimes the dogs abdomen appears distended or a mass is palpated (felt) by the owner or veterinarian.
  • Bruising is also common, due to the clotting problems that hemangioasarcoma causes.Skin or subcutaneous hemangiosarcomas are diagnosed with a surgical biopsy
How is it diagnosed?
  • Surgical biopsy is required to diagnose this disease. The appearance of a bleeding mass in the spleen on abdominal ultrasound, although it may be suspicious for hemangiosarcoma, it is not a definitive diagnosis.
  • Skin or subcutaneous hemangiosarcomas are diagnosed with a surgical biopsy.
How is this cancer treated?
  • Surgical removal of the bleeding mass-spleen and or liver--is the first step.
  • Because this tumor metastasizes (spreads) very rapidly, systemic therapy (chemotherapy and / or metronomic therapy) is often recommended.
  • For superficial hemangiosarcomas of the skin, the best treatment is wide surgical excision, and a cure is likely in cases where tumor-free surgical margins are obtained. Average survival time post-resection is 780 days. For subcutaneous masses or skin masses where wide, complete surgical excision is not possible, radiation therapy is often recommended.

 

When is chemotherapy recommended for hemangiosarcoma?

  • Adriamycin, vincristine and cyclophosphamide have been shown to increase average survival time following splenectomy. These drugs are well tolerated, with the majority of dogs experiencing above average quality of life.
  • Occasionally, splenic masses are found incidentally on routine abdominal ultrasound. Splenectomy at this early stage can result in long-term remission (greater than 1 year). In older patients at risk for splenic hemangiosarcoma, routine abdominal ultrasound can be used as part of a twice-annual wellness evaluation.            
  • Cardiac hemangiosarcomas are generally located in the wall of the right atrium and bleed into the pericardial sac (surrounding the heart). Surgical resection and creation of a pericardial window followed by chemotherapy can improve survival times. Most patients initially present with some degree of circulatory failure (severe weakness from poor perfusion of blood) that can be quickly relieved with pericardiocentesis (draining the fluid from the sac that surrounds the heart) and intravenous fluid therapy. Chemotherapy is recommended following this procedure.
What is the prognosis for dogs and cats with this cancer?
  • Survival time post-splenectomy rarely surpasses 3 months due to the high rate of metastasis (spread) to the liver and lungs. In fact, 60% of dogs have gross metastatic disease to these locations at the time of presentation. Chemotherapy is recommended to prolong survival time in both patients with gross metastatic disease and those without gross metastatic disease.
What is on the horizon for this cancer?
  • Hemangiosarcoma is a disease that may lend itself well to treatment with angiogenesis inhibitors (drugs that inhibit blood vessel formation). This group of drugs includes thalidomide, endostatin, angiostatin and soluble VEFG-receptor (soluble vascular endothelial growth factor receptor). While these drugs would not likely result in tumor regression, they may control the bleeding and thereby giving other forms of treatment (i.e. chemotherapy) more time to work.
  • Metronomic chemotherapy (low dose oral chemotherapy and a NSAID given on a daily basis) may be used to treat hemangiosarcoma as this form of treatment is anti-angiogenic (prevents or delays new blood vessel growth). Metronomic chemotherapy can be used alone or in conjunction with traditional chemotherapy.
  • Small molecule inhibitors are also being evaluated for treating this disease.

Localized histiocytic sarcoma,  disseminated histiocytic sarcoma and malignant histiocytosis are fairly rare tumors overall but occur with high incidence in Bernese Mountain dogs, Rottweilers, Flat Coated Retrievers, and Golden Retrievers. Histiocytic sarcomas are very aggressive tumors, and can therefore become very invasive (destroy normal surrounding tissues) as well as have a high rate of metastasis (spreading to other areas of the body). Localized histiocytic sarcoma lesions most commonly are found in the spleen, lymph nodes, lung, bone marrow, skin, brain, and joints of the limbs. Disseminated histiocytic sarcoma and malignant histiocytosis are multi-system, rapidly progressive diseases in which there is simultaneous involvement of multiple organs such as the spleen, lymph nodes, lung, bone marrow, and skin.

What causes this type of cancer in dogs and cats?
  • The cause of this group of diseases is largely unknown.
What are the common signs of this cancer?
  • Dogs with histiocytic sarcoma typically have non-specific signs, such as anorexia, weight loss, and decreased energy.
  •  Other signs depend on the organs involved and are usually a consequence of destructive mass formation. For example, if there is a large mass in the lungs, a dog may experience coughing or difficulty breathing. If the brain is involved, you may see seizures, incoordination, and paralysis. If a joint is involved, lameness or limping is often seen.
How is it diagnosed?
  • Most histiocytic sarcomas can be diagnosed via cytology (needle aspiration; where a small needle is inserted into the mass and cells are removed and evaluated under a microscope) or biopsy (a piece of tumor tissue is removed under sedation). Occasionally, a histiocytic sarcoma tumor can look identical to other types of tumors, so additional tests may be recommended to get a definitive diagnosis.
  • Due to the high risk of dissemination (spreading throughout the body) we typically recommend blood work, radiographs of the chest, and an ultrasound of the abdomen to look for evidence of disease spread. An evaluation of your pets’ bone marrow may also be recommended, especially if your pet is anemic. A bone marrow evaluation does require mild sedation, but is typically not painful for your pet.
How is this cancer treated?
  • If your pet has a localized histiocytic sarcoma, surgery or radiation therapy may be recommended as part of the treatment protocol. If the lesion is periarticular (in the joint tissue of a limb), amputation of that limb may be recommended or radiation therapy to the joint may be recommended.
  • If your pet has disseminated histiocytic sarcoma, surgery will likely not be recommended.
  • Due to the high rate of metastasis (spreading), some form of chemotherapy is usually recommended. There are several chemotherapy medications that have shown effectiveness in patients with histiocytic sarcoma, such as lomustine and doxorubicin.

Will chemotherapy be recommended? If there is spread of the disease at diagnosis or there is a high chance of the disease spreading then chemotherapy will be recommended.

Will radiation therapy be recommended?   If the disease is mostly localized, then radiation therapy will be recommended

What is the prognosis for dogs and cats with this cancer?
  • Longer survival times have been seen in dogs that have microscopic disease or have localized tumors that have been surgically removed. Disseminated histiocytic sarcomas and malignant histiocytosis are both aggressive diseases that have a generally poor response to therapy. There are individual animals that can, however, do well.
What is on the horizon for this cancer?
  • New drugs are currently being investigated for their effectiveness in the treatment of this disease. There is some indication that some drugs used to treat women with osteoporosis may be of benefit.

Melanoma is the most common tumor found in the mouth of dogs, and the second most common tumor found on the digits (toes). There is a predisposition for male dogs and certain breeds seem to be overrepresented, including Scottish terriers, Cocker Spaniels, Gordon Setters, Chow Chows, and Golden retrievers.  They are locally invasive tumors, often infiltrate deep into the bone (of the jaw or toe), and have a high rate of metastasis (spreading). Cats can also get melanomas but it is much less common than in the dog.

What causes this type of cancer in dogs and cats?
  • Damage to the DNA of skin cells (especially by UV light) has been shown to cause melanoma in people. The cause of melanoma in dogs and cats is less clear, since many of the melanomas occur in areas not directly exposed to UV light.
What are the common signs of this cancer?
  • Oral melanomas: The presence of a noticeable swelling in the mouth is the most common sign. Increased salivation, facial swelling, weight loss, bad breath, pain, inability to eat, dropping food from the mouth, and loose teeth are also common. These masses may be pigmented (black) or pink to white in color.
  • Digit (toe) melanoma: Swelling of the digit (similar to a toe infection) is often the first noticeable clinical signs. Some dogs will have loss of the toe-nail or limping on that leg. The tumors often are black in color.
How is it diagnosed?
  • Melanomas can be diagnosed with a fine needle aspiration and cytology-- a small needle is inserted into the tumor and some cells are removed from it and then evaluated. Since the mouth is a very sensitive location, most animals need some mild sedation for a needle aspiration. When located on the toe, sedation is typically not necessary.
  • Occasionally a needle aspiration is inconclusive, so a biopsy is required-- a small piece of tissue is removed (typically under sedation or anesthesia) and sent to the laboratory for a pathologist to look at under the microscope. Biopsies typically require anesthesia for both the mouth and toes.
  • All patients with a diagnosis of melanoma should have the local lymph nodes and lungs evaluated for evidence of metastasis. The local lymph nodes should be sampled with a fine needle aspiration and cytology (or biopsy under anesthesia). Radiographs or a CT scan should be used to evaluate the lungs for spread of the cancer. Occasionally an abdominal ultrasound will be recommended to evaluate the abdominal organs (i.e. spleen, liver, etc.) for evidence of metastatic disease.
How is this cancer treated?
  • Good local control of the primary tumor is very important in the therapy of melanomas. For oral melanomas, it can sometimes be difficult to remove the entire tumor without removing bone. Most dogs (> 85%) will continue to eat, drink, chew, and play with toys. For digital melanomas, the entire toe is removed with the tumor. A good wide aggressive surgical approach minimizes the chance for local recurrence.
  • The pharmaceutical company Merial has developed a new treatment called the melanoma vaccine (Oncept). It is a new DNA vaccine treatment that stimulates your dog’s immune system to fight the melanoma. This is not traditional chemotherapy and is tolerated extremely well by most dogs. 

 

Will chemotherapy be recommended for my dog?

  • Chemotherapy has been used in dogs that have tumors that are not surgically excisable, not responsive to radiation therapy or when metastatic disease is present. Novel therapy with small molecules that block tyrosine kinase receptors have also shown some promise. 

 

Does radiation therapy play a role in the treatment of melanomas?

  • Additional local control options for an incompletely excised (removed) tumor include a second surgery, if possible, or radiation therapy. Radiation therapy can also be used post-operatively (if tumor cells were left behind and cannot be removed) or if a tumor is too large to remove. Melanomas tend to be very responsive to radiation therapy.
What is the prognosis for dogs and cats with this cancer?
  • The average survival time of untreated dogs is only a few months.
  • Dogs with an oral melanoma that have good local control (surgery +/- radiation therapy if indicated) followed by the Merial melanoma vaccine have an improved median survival time of about 1.5-2 years (with many living much longer).
  • Dogs with digit melanomas have an average survival time of about 1 year with surgery alone. The melanoma vaccine, however, can dramatically improve survival times.
What is on the horizon for this cancer?
  • The FDA has recently approved a drug called Yervoy – a drug that “unblocks” the immune system and allows it to work better. This drug may be adapted to be used in dogs in the future.

Multiple Myeloma (MM) is a cancer of plasma cells, which are specific types of B-lymphocytes (white blood cells) which produce antibodies as part of the body’s immune system. Multiple Myeloma is a relatively uncommon cancer and there is no gender or breed predilection in dogs. The average age at the time of diagnosis is 8-9 years.

What causes this type of cancer in dogs and cats?
  • The exact cause of MM is unknown in dogs. In people damage to DNA or chromosomes are being investigated as possible causes.
What are the common signs of this cancer?
  • Affected dogs can exhibit signs of lethargy, weakness, lameness, bone pain (due to the destruction of bone caused by the malignant plasma cells), hemorrhage (e.g, petechiae on mucous membranes, gingival bleeding, or bleeding from the nose), polyuria / polydypsia (increased urination and thirst), and/or neurologic deficits. Other presenting signs of disease may include hypertension (high blood pressure), ophthalmic (eye) abnormalities, neurologic dysfunction (including seizures),
  • The clinical signs of multiple myeloma are highly variable and may affect multiple organ systems. The presentation of a patient with multiple myeloma will depend on the type of neoplastic cell, type of immunoglobulin (antibody) produced, location of lesions, and severity of growth and infiltration.
  • Clinical signs and symptoms may be present for up to 1 year before a definitive diagnosis of multiple myeloma is made. Patients can also present with recurrent infections, non-regenerative anemia, hypercalcemia, pathologic bone fractures, and/or seizures. Complications secondary to multiple myeloma may include kidney failure, infections secondary to immunosuppression, clotting disorders, chronic anemia, cardiac insufficiency, and neurologic dysfunctions.
How is it diagnosed?

Diagnosis of multiple myeloma in dogs requires at least two of the following criteria:

  1. Radiographic evidence of osteolysis (bone destruction)
  2. >20% plasma cells in bone marrow aspiration or biopsies
  3. Monoclonal gammopathy on serum protein electrophoresis
  4. Bence-Jones proteinuria—a particular type of protein in urine

 

Radiographic Evidence of Osteolysis

  • Areas of bony destruction (osteolysis) may be seen in ~40% of dogs suffering from multiple myeloma (in contrast, osteolytic lesions rarely are seen in cats).The bones most commonly involved in canine multiple myeloma include the spine, pelvis, ribs, skull, and proximal extremities. In addition, malignant plasma cell tumors present in the bone marrow are often osteolytic.
  • Survey radiographs may reveal focal, multifocal, or diffuse osteoporosis-type lesions. Clinically, the patient may present with pathologic fractures, rear limb lameness or paresis, or bone pain.

 

 Bone Marrow Aspirates with > 20% Plasma Cells

  • Bone marrow analysis is an essential procedure when multiple myeloma is suspected. Diagnosis is facilitated by taking aspiration and core marrow biopsies from areas of bone destruction (osteolysis). Cytologic evaluation of the bone marrow should reveal that plasma cells constitute > 20% of all nucleated cells in animals with MM.

 

Hyperproteinemia with Monoclonal Gammopathy

  • Hyperproteinemia (elevated protein) and an elevated globulin (a type of protein found in the blood) level can be easily detected on routine bloodwork.  . Serum electrophoresis should be performed on all patients that present with an elevated globulin level and signs suggestive of multiple myeloma.
How is this cancer treated?
  • Goals of treatment include decreasing tumor cell numbers as well as treating the secondary systemic effects
  • Chemotherapy is effective at reducing tumor cell numbers, decreasing bone pain, aiding in bone healing, and decreasing serum immunoglobulin levels
  • Chemotherapy can increase both the quality and quantity of life
  • The chemotherapy protocol of choice (for dogs) consists of oral Melphalan (Alkeran) and prednisone—in cats we use oral Chlorambucil (Leukeran) and prednisone. Other chemotherapy agents such as Cyclophosphamide can also be used. If advanced myeloma is diagnosed or if a patient becomes resistant to oral chemotherapy, intravenous chemotherapy may be used. The animals handle these therapies extremely well.
  • Radiation therapy also can be used with relatively good results in cases of isolated plasma cell tumors and can be very effective in treating the bone pain caused by this disease.
  • Supportive therapy is essential in animals with multiple myeloma to relieve immediate clinical problems.
What is the prognosis for dogs and cats with this cancer?
  • Median survival times of 18 months or longer can be achieved with chemotherapy and supportive care.

What is on the horizon for this cancer?
  • The use of a new class of drugs, called proteosome inhibitors has shown great promise in people. In addition, drugs like thalidomide have been working effectively in people for a number of years.

Primary lung tumors (cancer originating in the lung) are uncommon in dogs and account for less than 1% of all tumors. It is most common in older dogs, but no specific breed or sex is predisposed. They are almost always malignant (invasive with the potential to spread).

What causes this type of cancer in dogs and cats?
  • Although smoking is associated with most lung cancer in people; this is not true in dogs or cats. Second hand smoke can contribute to lung tumors in short-nosed dogs (it causes nasal cancer in long-nosed dogs).
What are the common signs of this cancer?
  • Clinical signs are typically vague and not specific to the respiratory tract. About 25% of dogs will show no clinical signs of illness at all. Many dogs will show signs of general malaise: tiredness and decreased appetite.
  • Symptomatic dogs can have a nonproductive cough
How is it diagnosed?
  • A thorough physical examination may revealed abnormal or muffled lung sounds
  • Radiographs (x-rays) of the chest are probably the most important tool to visualize a primary lung mass in a dog. A primary lung tumor is typically located in the caudal (towards the hind end of the dog) lung lobes, however can be located in any lung lobe. There is usually only a single mass present, unless the tumor has spread.
  • A CT scan can be used in lieu of or in addition to a standard x-ray (radiograph). CT scans provide greater clarity and reveal more details than regular radiographs and can detect smaller masses.
  • Additional imaging (such as abdominal radiographs or an abdominal ultrasound) is recommended to evaluate other organs for metastasis (spread of the tumor).
  • If the mass is big enough, and in the ideal location (close to the chest wall), an aspirate of the mass may be attempted with a small needle and syringe. This involves passing a needle through the chest wall and inserting it into the mass, then gently creating suction on the syringe to remove the microscopic cells for evaluation (cytology). This is a fairly safe procedure, but should be done using ultrasound guidance.
  • Biopsy of tissue from the lung mass is often the only definitive way to make a diagnosis of lung cancer. This requires some form of surgery, but there are many new less invasive procedures available-such as thoracoscopy and ultrasound/CT guided tru-cut biopsy.
How is this cancer treated?
  • Surgical excision of the tumor is the treatment of choice for canine primary lung cancer. Depending on the size and location of the mass, complete removal may not be possible, however, most tumors are at least somewhat removable. If there is evidence of widespread metastasis (spreading of the cancer in multiple locations), surgical removal is generally not an option.

 

Will chemotherapy be recommended?

  • If surgery is not an option, chemotherapy may be used to slow the progression of disease.
  • If a primary lung tumor is of a higher “grade” (more aggressive with a high chance of spreading to other locations) or has invaded into vessels or lymphatics, chemotherapy may be used to slow the rate of metastasis (spreading). A tumor grade is obtained after a biopsy or surgical removal of the tumor.
What is the prognosis for dogs and cats with this cancer?
  • The average survival times for dogs with primary lung cancer is variable, and depends on many factors including spread of the primary tumor, the presence of invasion into vessels or lymphatics, the size of the tumor, and the grade of the tumor.
  • Dogs with small, low-grade (well-differentiated) tumors without lymph node involvement carry a very good prognosis, and have an average survival time of 16 months or longer with surgery alone whereas dogs with high-grade (poorly differentiated) tumors with lymph node involvement have an average survival of 2 months if surgery is the only treatment.
What is on the horizon for this cancer?
  • The use of targeted therapies and non-steroidal anti-inflammatory drugs (NSAID) are currently being investigated in the treatment of this tumor when used in conjunction with surgery and traditional chemotherapy.

Soft tissue sarcomas (STS) make up a large category of tumors that arise from connective tissue. This category includes tumors of fibrous tissue, fat, smooth muscle, nerves, and lymphatic vessels. The diagnosis of soft tissue sarcoma includes fibrosarcomas, malignant peripheral nerve sheath tumors, histiocytomas, myxosarcomas, liposarcomas, lymphangiosarcomas, and undifferentiated sarcomas. STS comprise ~15% of all skin/subcutaneous (under the skin) tumors. These tumors are typically very invasive to the surrounding tissue but generally have a low risk of spreading (metastasis).

What causes this type of cancer in dogs and cats?

N/A

What are the common signs of this cancer?
  • Tumor location plays an important role in the behavior of STS. STS of the oral cavity or areas that are difficult to do surgery in (such as the axilla or “armpit”) are more aggressive than tumors of the trunk or extremities.
  • STS of the trunk and extremities behave similarly in that they are invasive into the surrounding tissue, often extending far beyond gross margins—where you can feel or see the tumor. Microscopic tumor cells can extend up to 5cm beyond the visual tumor.
  • When biopsied, STS are given a grade by a pathologist based on features seen under the microscope, including mitotic index (amount of actively dividing cells), percent of tumor necrosis (amount of dying cells), and degree of differentiation (how similar the cells are to normal cells).  Based on these factors, a tumor is given a grade (1, 2, 3, OR low, intermediate, high). Tumor grade is highly predictive of how the tumor is going to behave, with higher grade tumors having a higher chance to spread and re-grow locally. Metastasis (spread to a distant organ) occurs in ~10% of low grade tumors, ~20% of intermediate grade tumors, and up to 50% of high grade tumors.
How is it diagnosed?

N/A

How is this cancer treated?
  • Wide surgical excision is always the treatment of choice when feasible. The completeness of this surgical removal is determined by the pathologist by microscopically examining all surgical margins.
  • Recurrence of the tumor is 10 times more likely in patients with histologically incomplete surgical margins than patients undergoing wide surgical resection with adequate margins.

What role does radiation therapy play in the treatment of STS?

  • Radiation therapy is very effective at preventing tumor recurrence when performed following incomplete resection of low to intermediate grade STS. Local control of 5 years or longer can be achieved in many cases. Radiation therapy alone (without surgery) is less effective for treating tumors that have not been surgically removed.
  • Radiation therapy can also be used in a palliative (pain relief) setting for tumors that are not amenable to surgical excision or have failed other forms of therapy.

  

What role does chemotherapy play in the treatment of STS?

  • Intravenous chemotherapy may be of benefit in 2 situations:
    1. Used prior to surgery to help shrink a very large intermediate or high grade STS
    2. Following complete resection of a high grade STS to prevent metastasis
What is the prognosis for dogs and cats with this cancer?
  • The prognosis often depends upon the grade and the location of the tumor. For low grade tumors that are able to resected with clean wide margins, the prognosis is excellent with most dogs living disease free for over 5 years.
  • If a complete, wide surgical excision is not possible; radiation therapy is very effective in the treatment of these tumors.
What is on the horizon for this cancer?
  • The importance of angiogenesis (blood vessel growth) for the development of the primary tumor and distant metastatic disease is well understood for all cancers including STS. Using drugs to slow down or stop this blood vessel growth is called metronomic chemotherapy and involves low dose oral chemotherapy in conjunction with a non-steroidal anti-inflammatory agent. It is designed to effectively delay tumor re-growth (in incompletely excised tumors) and possibly prevent or delay metastasis (spread).

Thymomas are rare tumors that arise from the epithelium (lining) of the thymus gland in the dog and cat. They are typically diagnosed in older animals, with the median age in dogs being 9 years and in cats it is 10 years. There is no breed predilection but medium and large dogs are overrepresented. Thymomas are considered benign or malignant based on their clinical features rather than on histologic (under the microscope) features. Benign thymomas do not invade into adjacent structures within the chest cavity while malignant thymomas do invade adjacent structures

What causes this type of cancer in dogs and cats?

N/A

What are the common signs of this cancer?
  • Patients may show signs of respiratory distress such as coughing or difficulty breathing
  • Facial, neck, or front limb swelling may occur due to the obstruction of the blood vessels or the lymphatic vessels -a condition known as precaval syndrome
  • Up to 40% of dogs with thymomas (and occasionally cats) will have signs of myasthenia gravis. This  syndrome is characterized by muscle weakness and megaesophagus (distension of the esophagus which can cause chronic regurgitation)
  • Immune-mediate anemia can be seen in patients with thymomas
  • A severe form of dermatitis (skin disease) has been associated with thymomas in cats
How is it diagnosed?
  • Staging tests include cbc/chemistry/urinalysis, chest radiographs (x-rays), chest ultrasound, and in some cases a CT scan
  • Thoracic (chest) radiographs typically show an anterior mediastinal mass (mass in the front portion of the chest cavity), pleural effusion (fluid around the lungs), and occasionally megaesophagus (distended esophagus) 
  • Cytology (aspirate) of the mass or of the pleural fluid can be performed but typically does not yield a diagnostic sample (the epithelial cells of the tumor)
  • Typically lymphocytes are the cells seen on cytology which can make differentiating a thymoma from another cancer, such as lymphoma, difficult
  • With a thymoma mature lymphocytes should be visualized on cytology whereas with lymphoma lymphoblasts (immature lymphocytes) would be seen
  • Flow cytometry (an advanced  type of test that evaluates every cell in a sample using lasers) can be used to help differentiate between thymoma and lymphoma.
  • A biopsy is needed to confirm the diagnosis of the thymoma. Biopsy is usually obtained at the time of surgical removal of the tumor/mass.
How is this cancer treated?
  • The best therapy for thymoma is surgical removal (a CT scan may be performed prior to surgery to determine how invasive the tumor is but ultimately, visualization of the tumor while in surgery is necessary to determine if a particular mass can be removed  surgically).
  • Treatment for myasthenia gravis must also be provided in patients suffering from it. 
  • If a thymoma cannot be removed or if the entire tumor cannot be removed with surgery, radiation therapy can be used to treat the remaining mass.

 

Will chemotherapy be recommended? Sometimes chemotherapy can be recommended, but it is not the most common therapy recommended.

 Will radiation therapy be recommended? Radiation therapy will be recommended in many cases of this tumor when the entire mass has not be widely resected by surgery.

What is the prognosis for dogs and cats with this cancer?
  • The prognosis for dogs with surgically resected benign thymomas without megaesophagus is good, with long term remissions and cures seen
  • In dogs whose tumors are surgically resectable and who do not have myasthenia gravis there is a greater than 80% survival at 1 year
  • In cats the median survival time was almost 2 years for surgically resected thymomas
  • Patients with non-resectable thymomas generally have a poorer prognosis and show variable responses to radiation and chemotherapy
What is on the horizon for this cancer?

N/A

Thyroid tumors account for 1.2 % to 3.8 % of all tumors in the dog and typically develop in older dogs with a median age of 9-11 years. There is no gender predisposition but Golden retrievers, Boxers, and Beagles are over represented. Most thyroid carcinomas are non-functional (meaning they don’t produce thyroid hormones); 60% of patients have normal thyroid function; 30% are hypothyroid (under active thyroid); 10% are hyperthyroid (over active thyroid). Approximately 30-40% of thyroid carcinomas will have already metastasized (spread) at the time of diagnosis and ~80% will ultimately develop metastasis.

What causes this type of cancer in dogs and cats?
  • The cause of thyroid cancer in dogs is largely unknown.
What are the common signs of this cancer?
  • Most dogs have a mass that is noticed on the ventral neck
  • Most patients are asymptomatic (not signs of disease)
  • Less common signs that some patients will present with include: coughing, change in quality of their bark, trouble swallowing, trouble breathing, facial swelling/edema
  • Patients may have signs related to hypo- or hyper-thyroidism if the thyroid carcinoma is functional
How is it diagnosed?
  • A CBC; chemistry panel; urinalysis are needed to assess total body function
  • Thyroid panel is needed to determine if thyroid function is normal, under active, or over active
  • 3 view thoracic (chest) radiographs
  • Aspiration and cytology of the regional lymph node(s)
  • Ultrasound and CT scan of the mass can be used to help evaluate how invasive it is into the surrounding tissues/structures and if the tumor can be removed surgically
  • A fine needle aspirate and cytology can be performed but is unfortunately not very accurate when it comes to making a diagnosis of thyroid carcinoma
  • A biopsy (taken at the time of surgery) is required to make a definitive diagnosis of thyroid carcinoma
How is this cancer treated?
  • The treatment of choice is surgical resection when the mass is freely movable and not invading surrounding structures
  • Thyroid carcinomas that cannot be completely removed can be treated with radiation therapy
  • Patients with incomplete surgical resection, metastatic disease, or evidence of more aggressive tumors can be treated with chemotherapy (in addition to surgery and/or radiation therapy). Signs of tumors that have a higher chance of spreading include capsular/vascular invasion, large tumors, or bilateral tumors (masses of both the right and left thyroid glands). 
  • Anti-angiogenic (metronomic) chemotherapy is also an option for reducing tumor growth
  • Low dose thyroid  supplementation may also help by inhibiting growth of the cancer cells
  • Radioactive iodine, a common treatment for thyroid cancer in people, is infrequently used to treat  thyroid cancer in dogs. 
What is the prognosis for dogs and cats with this cancer?
  • The median (average) survival time after complete surgical excision for non-invasive, freely movable masses is about 3 years
  • The median survival time after surgical excision alone for more invasive masses is 6-12 months
  • Dogs treated with radiation  therapy without evidence of metastatic disease can have median survival  times of over 2 years
What is on the horizon for this cancer?
  • Targeted therapies are currently being evaluated In the therapy of this tumor