Overview of Treatments

Depending upon the grade, stage and type of cancer, your team will recommend one or a combination of treatment options. Multiple treatment options that combine surgery, radiation and chemotherapy are the rule rather than the exception. This is because the treatment of cancer in animals has become as sophisticated and successful as the treatment of cancer in humans.

Chemotherapy

Chemotherapy is used to treat cancer at the tumor site, as well as the cancer that may have spread through the body. Most chemotherapeutic drugs act directly on cancer cells, preventing them from maturing or reproducing. Unlike humans, the side effects of chemotherapy in pets are relatively mild. Doses of drugs and treatment schedules are calculated to minimize discomfort to the pet, while providing the most effective defense against the cancer. As a result, most people are surprised at how well their pets feel while undergoing chemotherapy. The goal is to kill and slow the growth of cancer cells, while producing minimal negative effects on normal cells. If your pet requires a plan of chemotherapy, your veterinarian will most likely bring in a specialist (an oncologist) to develop the plan of attack and administer the treatments. In addition to the latest and best medical treatments, an oncologist will provide the specialized equipment and supervision that your pet needs. Chemotherapy protocols are frequently changed or customized to achieve the best outcome for your pet.

Under what conditions is Chemotherapy used?
Chemotherapy is a systemic therapy, meaning it works throughout the body--as opposed to radiation therapy which is a local or regional therapy. Chemotherapy is used when a cancer or tumor has already spread (or metastasized) or when there is a high risk of the tumor spreading.

Which tumors are commonly treated with Chemotherapy?
Many types of cancers are treated with chemotherapy. The most common tumor being lymphoma, a systemic cancer of part of the immune system. Osteosarcoma (bone cancer) and hemangiosarcoma are both treated with chemotherapy because of the very high likelihood of metastasis (spreading), even after the tumor is removed. Many other types of cancers such as mast cell tumors, mammary gland tumors, bladder cancer, and many others are often treated with chemotherapy.

How is Chemotherapy administered?
Chemotherapy can be administered orally in the form of a pill or injected into a vein (intravenous), into a body cavity (such as the chest or bladder), into a muscle (intramuscular), or into the spinal fluid (intrathecal). Currently, most chemotherapy is administered intravenously; however, oral chemotherapy drugs are gaining wider use.

Are there any side effects?
Chemotherapy in pets is very different from chemotherapy in people. We use much lower doses of chemotherapy and spread the treatments out over a much longer period of time. This is done to try and allow us to treat your pet's cancer effectively without causing the side effects that occur in people. In addition, there have been tremendous advances in medications that are used to prevent the common side effects of chemotherapy-vomiting, diarrhea and loss of appetite. Cerenia is a relatively new drug and it is quite effective at preventing or stopping nausea and vomiting. There are also regimens that we have developed that dramatically reduce the side effects of diarrhea and loss of appetite. We are as concerned as you are about maintaining the highest quality of life for your pet-both during and after treatment.

How Should I prepare for treatment?
Most chemotherapy is given in an outpatient setting, typically over a 5-45 minute time period. Some chemotherapy is given slowly over a few hours, but our team will alert you when this is needed. Most animals do not need to be fasted before chemotherapy, but we will make recommendations based upon your pet's unique circumstances.

What should I expect after treatment?
Most pets-80-90%- have no or minimal side effects after chemotherapy. Vomiting, diarrhea, loss of appetite and loss of energy are the four most common side effects, but if these do occur they are usually mild. Your oncologist will discuss ways of preventing these side effects, as we have found that it is easier to prevent them than it is to treat them once they begin. Greater than 95% of our clients were pleased with how their pets handled therapy at our practice and would do it again.

Radiation Therapy

In veterinary medicine, radiation therapy was first attempted at the beginning of the twentieth century. During the past 50 years, major advances have been made. The use of histopathology, MRI, and CT scans has resulted in more accurate diagnosis of the type and location of tumors. Newer radiation equipment and new technology such as intensity modulated radiation therapy (IMRT) has allowed the radiation to be tailored to the individual patient's tumor with more and more accuracy, so that normal tissues around the tumor can be spared. This has increased the effectiveness and decreased the side effects and risks of radiation therapy.

Under what conditions is radiation therapy used?
Radiation therapy can be used alone or in combination with surgery and/or chemotherapy to provide long term control or death of a tumor. It is used for tumors that have not spread to other sites in the body and offers a potential cure for some localized tumors. In other cases, radiation therapy can be used for its palliative effect (relieving pain or other signs of disease). Even if the tumor cannot be destroyed, radiation may result in rapid pain relief and may shrink the tumor or slow down tumor growth. This often will improve the quality of life of the animal.

Which tumors are commonly treated with radiation therapy?
Tumors that are commonly treated with radiation include oral tumors, nasal tumors, brain tumors, nasal tumors, mast cell tumors, soft tissue sarcomas, bone tumors and many more. However, radiation can be used to treat almost any localized tumor and it is sometimes used to treat widespread tumors. Radiation can often be an effective treatment for tumors when surgery either is not possible because it will be too dangerous. For example, tumors in certain locations in the brain may best be treated with radiation alone.

Many times radiation will be used after surgery if the tumor cannot be removed completely with surgery. This is commonly done for soft tissue sarcomas, mast cell tumors and other superficial tumors in areas where the tumor cannot be fully removed.

How is radiation administered?
If your pet is a candidate for radiation and you decide to go ahead with treatment, your oncologist/radiation oncologist will talk to you about how many treatments your pet will need and the side effects that you should expect. Sometimes a CT scan will be needed to plan the radiation, even if your pet has had an MRI or CT scan already. This scan is done with your pet in a positioning device that will be used for each future treatment. The scan is then used to develop a radiation plan that is customized for your pet's specific tumor, to treat your pet effectively with as few side effects as possible.

For each treatment your pet will need to be placed under general anesthesia to make sure that they stay perfectly still for the treatment. Although there is always a risk any time an animal is placed under anesthesia, the anesthesia for radiation is typically very short and very short acting drugs are used, so potential complications are rare.

Are there any side effects?
Side effects of radiation for your pet will depend upon the dose of radiation used to treat the tumor and also the type of radiation that is used. With daily, definitive treatments the normal tissues around the tumor will often develop redness and irritation. Sometimes this can cause significant discomfort for your pet. Newer radiation technology allows us to minimize these side effects in most patients. However, pets who are likely to develop significant side effects will often require pain medications or anti-inflammatory medications. Your oncologist/radiation oncologist and your regular veterinarian will work as a team to keep your pet as comfortable as possible. These side effects are almost always temporary and the goal in these situations is to get your pet through the side effects and back to having a normal or improved quality of life after the treatment. Often there can also be a risk of a long-term, permanent side effect from radiation. Fortunately these side effects are rare and your oncologist/radiation oncologist will discuss these with you before starting treatment.

How Should I prepare for treatment?
Usually your pet will need to have food and water taken away the night before each treatment, but your doctor will confirm this with you to make sure that it is safe to do this. If your pet gets groomed on a regular basis it may be a good idea to have them groomed prior to radiation. Once the radiation starts you may not be able to have your pet bathed or groomed because there will be marks on their skin that cannot be removed.

What should I expect after treatment?
Following radiation therapy side effects may progress for up to two weeks if your pet develops side effects. Your oncologist/radiation oncologist will work with you and your pets regular veterinarian to manage your pets comfort level and managing their medications. A recheck exam is typically recommended in one to two weeks to make sure that the healing process is going well. Your pet also should have routine recheck exams to monitor for regrowth of the tumor or for late side effects from the radiation. A plan will be set up to have these done at The VCC or with your pet's regular veterinarian.  

 

Intensity Modulated Radiation Therapy (IMRT)

Intensity Modulated Radiation Therapy or IMRT may be used to treat your pet's tumor. This is a relatively new type of treatment that uses multiple, complex beams of radiation to shape the radiation dose to your pets tumor. By pinpointing the radiation to the tumor it minimizes the amount of radiation that is given to your pet's normal tissues. This will usually minimize the potential side effects for your pet. Many times this is done as part of a definitive radiation treatment using the same number of treatments, but it also can be done as part of a treatment known as stereotactic radiation or stereotactic radiation. This involves a small number of treatments contoured to your pet's tumor. This is a very effective way to deliver high doses of radiation to certain tumors.

Immunotherapy

Immunotherapy is the use of the body's immune system to treat a disease. We use immunotherapy to treat certain cancers, such as: melanoma, hemangiosarcoma, renal cell carcinoma, multiple myeloma, and lymphoma among others.

There are various types of immunotherapy ranging from cancer vaccines to injecting cytokines (chemicals that stimulate the body's own immune system). One of the advantages of immunotherapy is that it is generally less toxic than traditional chemotherapy.

Under what conditions is Immunotherapy used?
When a tumor is immunogenic—recognized as foreign by the body—immunotherapy can be very effective. We are actively engaged in research to find what tumors are immunogenic and what types of immunotherapy work in dogs and cats.

Which tumors are commonly treated with Immunotherapy therapy?
The most common tumor is melanoma. A tumor vaccine, the first of its kind in veterinary medicine, was developed to treat this disease and its use has revolutionized the way we treat this disease. Other vaccines for other types of cancers are currently in development.

How is Immunotherapy administered?
Subcutaneous methods consist of administration through subcutaneous routes, i.e., injections as well as infusions over time.

Are there any side effects?
The main side effects of this type of therapy are "flu-like" symptoms of malaise and loss of appetite.

How Should I prepare for treatment?
Typically, no preparation is necessary for this type of treatment.

What should I expect after treatment?
Your pet may be slightly lethargic and have a decreased appetite for a few days. The tumor may not respond initially, as immunotherapy may take weeks to months to work.

 

Surgery

Surgery is the oldest form of cancer therapy and has been responsible for the cure of more patients than any other treatment. This great success is mainly due to the development of new surgical techniques combined with chemotherapy and radiation for a total plan of treatment for your pet's cancer.

Under what conditions is Surgery used?
Surgery is a local treatment- meaning the surgeon is trying to remove the mass/tumor from a particular location. Most tumors start in one spot, which is why oncologists stress early detection as a way to increase the chance of successful therapy. If the cancer is found in only one location and the removal of the mass will not adversely affect your pet's quality of life, then surgery will be recommended.

Even if the tumor cannot be removed, surgery is routinely used to obtain a biopsy. This allows oncologists to determine the exact type of cancer your pet has, and this allows us to customize therapy so that we can give you and your pet the best results possible.

Which tumors are commonly treated with Surgery?
Any tumor that does not spread (metastasize), has a low chance of spreading, or has not spread yet can be treated with surgery. Common tumors, such as soft tissue sarcomas, osteosarcomas, hemagiosarcomas, mast cell tumors, skin tumors, oral tumors, brain tumors, liver tumors, and gastrointestinal tumors are among the many types of cancer for which surgery can be utilized.

How is surgery done?
Surgery is a technology consisting of a physical intervention on tissues. Other procedures such as angioplasty or endoscopy, may be considered surgery if they involve "common" surgical procedure or settings, such as use of a sterile environment, anesthesia, antiseptic conditions, typical surgical instruments, and suturing or stapling.

Are there any side effects?
Any surgical procedure can produce side effects. These side effects are typically short lived and are very dependent on the area of the body that the surgeon worked on. Your pet's surgeon will typically discuss pain management with you as there are now more ways than ever before to decrease or even prevent post-operative pain.

How Should I prepare for treatment?
Most surgical procedures require anesthesia, therefore your pet should be fasted (no food and no water) prior to surgery. Please ask the surgeon for the details on how long before surgery you should take away your pet's food and water, as this varies between surgical procedures.

What should I expect after treatment?
Your pet may be quiet or lethargic (low energy level) after surgery. Your pet may need to be hospitalized for a few days depending on the type and extent of the surgical procedure. You should talk to the surgeon prior to surgery to insure that you and your pet are well prepared for the post-operative period. The post-operative period is incredibly variable based upon the type, extent and duration of the surgical procedure as well as your pet's general overall health.