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.  

Stereotactic radiation (SRT) & Intensity Modulated Radiation Therapy (IMRT)

Stereotactic radiation (SRT) and Intensity Modulated Radiation Therapy (IMRT) are becoming more readily available for animals. In the past, traditional radiation therapy to treat cancer in pets would usually result in significant side effects and many owners would decide not to pursue treatment because of this. IMRT and SRT are changing the way that we are able to treat cancer in pets, and they have great potential to improve both your pet’s quality and quantity of life. The Veterinary Cancer Center is pleased to be able to offer these treatments for pets with cancer.

What is Stereotactic Radiation or Stereotactic Radiosurgery?

 

Stereotactic radiation, also known as stereotactic radiosurgery, involves delivering a small number of large radiation doses to the tumor, in the hope of causing maximal tumor damage while limiting the dose to the normal tissues. Usually this is done in 1 to 3 treatments over a short period of time. With stereotactic radiation, a large number of beams are directed at your pet from all different angles and the shape of the radiation beam is changed, during treatment, to deliver radiation where it is needed most.

What tumors can be treated with SRT?

SRT can be used to treat a variety of tumors, including brain tumors, pituitary tumors, nasal tumors and other tumors involving the head and neck. It also can be used to treat tumors of the spine and some parts of the abdomen or chest. It can be used for pets when daily visits and anesthesia may be too dangerous.

What is Intensity Modulated Radiation Therapy or IMRT?

IMRT uses the same technology as SRT with a large number of beams to attack the tumor from all angles while each beam is shaped to precisely deliver the radiation where it needs to be directed. With IMRT similar doses are used that have been used for conventional radiation in the past. However, IMRT allows the dose of radiation to be targeted at the tumor, with great precision, to avoid treatment of the normal tissues. This allows the same or higher doses of radiation to be delivered directly to the tumor, with fewer side effects for your pet.

What tumors can be treated with IMRT? IMRT can be used to effectively treat nasal tumors, brain tumors, pituitary tumors anal sac carcinomas and a number of other tumors. In any location where radiation side effects might be a problem, IMRT can be used to help minimize them.

Why does my pet need another CT scan for treatment?

If your pet with cancer has already had a CT scan or an MRI to diagnose their tumor, they may need a second CT scan for radiation planning. The first CT or MRI is useful to help determine where your pet’s tumor is, but the radiation planning CT is necessary for your pet for treatment. With newer radiation technology, as we tighten, or conform, the does tightly around the tumor, it is critical that your radiation oncologist know exactly where they are treating. Therefore a second CT scan is often necessary for this. Usually, your pet will be placed in a positioning device such as a bite block and/or vacuum bag, to make sure that they are positioned the exact same way for the CT scan and for each treatment. The CT scan requires a short anesthesia, but it is well worth it to make sure that your pet is receiving the most accurate delivery of their radiation dose.

What are the potential side effects for my pet?

One of the main benefits of IMRT and Stereotactic radiation is that they can minimize the side effects from radiation, making treatment much more tolerable for you and your pet. With traditional radiation treatments there are often significant side effects in the local area from damage caused by the radiation. With IMRT and SRT the dose of radiation can be targeted very tight around the tumor, using a radiation plan that is customized for your pet, minimizing the dose of radiation that is given to your pet’s normal tissues. In some areas, such as the head or pelvis, this is critical for avoiding severe side effects. For example, traditional conformal radiation for nasal tumors in dogs usually results in severe inflammation and burning in the mouth, around the eyes and the skin of the face.

There is also a risk of a severe, long-term complication in the eyes, the brain or the local bones. With IMRT and SRT, the dose of radiation to these structures can be minimized, limiting side effects to small areas. This means a better quality of life for your pet. With any type of radiation treatment a brief anesthesia is usually required. This anesthesia is needed to make sure that your pet stays perfectly still for each treatment. It is usually a short anesthesia, and your pet is monitored very closely while under anesthesia.

Even when radiation patients have anesthesia every day, the risk of significant complications is very low. Your radiation oncologist will evaluate your pet to make sure that they are likely to handle the anesthesia well and may recommend additional staging tests, such as radiographs, ultrasound, an echocardiogram, bloodwork and or urinalysis to help make sure that your pet is a healthy candidate for anesthesia. Another potential benefit of SRT is that it may be able to limit the number of treatments that your pet will need, minimizing the risk of anesthesia complications.

How can I find out more about IMRT or SRT for my pet?

If your pet has been diagnosed with cancer, and you want to learn whether IMRT or stereotactic radiation would help your pet, you should make an appointment to meet with our radiation oncologist, Dr Farrelly. We will evaluate your pet and their medical records and talk to you about what type of treatment options are best for your pet.

Half Body Radiation

Most dogs with lymphoma will go into remission after only a few treatments and they will often stay in remission for months. During this time, aside from having to come to see the oncologist for treatment, their quality of life is often very good. Once they get into remission owners often report that they are running, playing or just living their normal life as if they never had cancer. Unfortunately, almost all of these pets will eventually come out of remission and succumb to their disease. In the past twenty years there has been little to no improvement in the remission and survival times with chemotherapy alone. With this protocol, dogs are first treated with chemotherapy to get them into remission and this is followed by two treatments of half body radiation.Then a low dose rate is used, meaning that dogs develop almost no side effects from the treatment. They can get some changes to their hair coat and some intestinal upset, but otherwise they are typically fine. Most dogs will then go on to complete a shortened chemotherapy protocol. Initial results suggest that by combining radiation therapy with chemotherapy in this way dogs are in remission longer and are living longer with lymphoma.

Strontium – 90

Strontium – 90 probes have been used to treat small superficial tumors, including mast cell tumors in cats, solar induced squamous cell carcinomas in cats, small mast cell tumors in some dogs like pugs. It may be beneficial in palliative treatment of squamous cell carcinoma under the tongue in cats. It is great for treating pets with multiple tumors, because each treatment is usually less than ten minutes, and requires only a short anesthetic episode. For pets with multiple tumors it allows us to treat all of their tumors in one, shorter anesthesia. Also, it can be very helpful for treating eyelid tumors or corneal tumors, which are often very difficult to remove with surgery.

Clinical Trials

The Veterinary Cancer Center (The VCC) and Animal Clinical Investigation (ACI) are always looking for the best ways to diagnose and treat cancer in animals. Sometimes, the best ways are still unknown to science. Because of this, The VCC and ACI have partnered to create a Clinical Trials Center – the first of its kind – where new ways of treating and diagnosing cancer are evaluated. For more information on our current trials please click here...

Immunotherapy

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.