Radiation Therapy

How Does Radiation Therapy Work?

Radiation destroys the ability of cells to divide and grow. Both normal and cancer cells are affected, but the radiation treatment is designed to maximize killing the cancer cells and minimize adverse effects on the normal cells. Maximizing the effect on the tumor is one reason radiation therapy is given in a series of treatments rather than in one treatment. 


Are there risks involved? 

There are some risks involved with any type of cancer treatment. Side effects may be apparent because radiation can affect both normal cells and cancer cells. Usually these side effects are outweighed by the benefit of killing cancer cells.


Radiation therapy requires that the animal be completely still during treatment. Thus, general anesthesia is necessary for each treatment. There is always a risk associated with general anesthesia, but nearly all cancer patients withstand this portion of the treatments very well. A full medical work-up helps to identify potential problems prior to anesthesia. 


How is radiation therapy delivered?

In radiation therapy, a machine directs high energy radiation (x-rays) to the cancer and to some of the normal tissue around it. At the LSU-SVM Cancer Treatment Unit, a linear accelerator is used. Each treatment only takes approximately 15-30 minutes. Typically treatments are done daily (M-F) and patients are allowed to go home the same day. 


Your pet has been or will be examined by one or more oncologists. These oncologists will determine whether or not radiation therapy will be a useful treatment for your pet's cancer. If radiation therapy is given to your pet, radiation oncologists will plan the treatment very carefully. Treatments for each patient are different and are based upon that pet's tumor type and location, as well as the goal of therapy. On the first day of radiation therapy, the radiation oncologists and radiation therapists work together to ensure that your pet's treatment is delivered precisely as planned. Subsequently, the radiation therapists will perform the daily treatments. These specially trained individuals work as a team with the oncologists to ensure accurate radiation delivery. 


Is radiation therapy expensive?

Treatment of cancer with radiation therapy can be costly. It involves very complex equipment as well as the expertise of many health care professionals. The exact cost of radiation therapy varies with the type and number of treatments required. 


How long does the treatment take?

Radiation therapy is given in a series of treatments (called fractions) administered on consecutive weekdays or once per week. This schedule helps protect normal, healthy tissue by spreading out the total dose of radiation over a period of time. The total dose used and the number of fractions in which the total dose is given depends on many factors and may be different for individual patients. These factors include the size and location of the cancer, the general health of your pet, and the type of cancer present. 


What are the effects of the treatment?

During the course of treatment, the therapists and oncologists will monitor the effect of the radiation on the cancer as well as on the normal tissue. It may be necessary to alter the radiation plan or treatment schedule because of changes in the tumor or normal tissue, but this is not usually necessary. Most side effects that occur during radiation therapy, although unpleasant, are usually not serious. Usually, side effects begin about halfway through the planned course of therapy. In some cases, side effects may get worse in the 1-2 weeks following treatments before they begin to improve.


Many animals develop skin changes in the area being treated. Redness of the skin may develop near the end of, or after, radiation therapy is complete. This may progress to skin moistness, similar to eczema. This moistness may cause the animal to scratch, but it is important NOT to allow this. Your pet's radiation oncologist may prescribe medication and/or physical means to prevent scratching. It is inadvisable for you to purchase over-the-counter drugs to treat these conditions yourself unless instructed to do so. This skin moistness will usually subside in 7-10 days.


Hair loss in the treated area is common. This will occur after the radiation therapy is over. Hair loss in the treated area may persist up to 6 months, but some hair re-growth occurs in most patients. The color of the re-growing hair and skin in the treated area are likely to change. Dark hair and skin usually come back lighter in color while light skin and hair may come back darker.


It is unusual for animals to become nauseated and have vomiting or diarrhea as a result of the radiation therapy. This will usually only occur if portions of the abdomen are irradiated. It is also unlikely that your pet will have any side effects from anesthesia since the actual treatment time is so short. 


When a cancer of the oral and nasal cavity is treated with radiation therapy, a foul odor may develop as the tumor is destroyed by the radiation. This odor is usually temporary and decreases as the tumor dies. Antibiotics are commonly prescribed to help decrease the bacterial population in the mouth and the odor. Also, some animals will develop a dry mouth if the salivary glands are included in the treatment field.


The radiation oncologist will discuss any additional anticipated side effects that may occur in the normal tissues surrounding your pet's tumor. Rarely, side effects related to radiation can occur in the radiation field several months to years following completion of therapy. Therefore, if your pet ever develops abnormalities of any type within the radiation field, your radiation oncologist should be contacted for advice. 


What happens after treatment? 

It is important for your oncologist to examine your pet periodically after radiation therapy is complete. Typically, post-radiation re-checks are scheduled at 2 weeks, and 1, 3, 6, 9 and 12 months after treatment. Re-checks after this time are usually scheduled at 3-6 month intervals, depending on the type of tumor your pet has. The purpose of these re-checks is to evaluate the tumor for response to therapy and to evaluate your pet for side effects related to radiation therapy. The specific results to be expected depend on many factors. Your pet's doctor will provide specific details on the likelihood of success as part of the evaluation process.


Finally, it is important to realize that even though your pet may never be totally the same as before the cancer was diagnosed; it is possible in many pets to provide additional comfortable months or years of happy life through radiation therapy.  


What should I expect when I bring my pet in for the first radiation therapy? 

You will be asked to make a drop off appointment. On your arrival, please check in with the front desk at your scheduled time. An oncology technician or student will admit your pet to the hospital and obtain information on how your pet has been doing since the last visit. A clinician may not be available to talk to you at this time. The technicians will be able to answer many of your general questions regarding radiation therapy. If you have more detailed questions please feel free to call prior to your pet's first radiation treatment.


If I am coming daily, can I set up a drop off time and pick up time?

After the first radiation treatment, one of the radiation technicians will discuss drop off and pick up times with you. The time may vary due to other service needs. You will need to schedule a drop-off appointments for each of the radiation treatments. If you are leaving your pet for the day, drop-offs are admitted between 7:45-9:00 a.m. and you can pick up your pet between 4:00-5:00 p.m.


Does my pet need anesthesia?

Your pet will be undergoing anesthesia for each radiation treatment. We need to specifically treat the tumor and avoid surrounding tissue so it is important that our patients hold perfectly still. The first time under anesthesia will last a variable time period but it is always longer than the daily treatment. Anesthesia protocols are tailored specifically for each individual patient. The anesthesia is administered by the radiation technicians under the supervision of a veterinarian. There is always a risk associated with anesthesia. The risk of anesthesia is minimized by having a full medical work-up prior to anesthesia. If there concerns about your pet's reaction anesthesia, a board-certified anesthesiologist is available for consultation.


May I feed my pet in the morning?

Due to the requirement for general anesthesia for the radiation treatment it is important that you DO NOT FEED your pet after 10:00 p.m. the night before each radiation treatment. Your pet may have water throughout night until the time you leave for the hospital unless specifically directed by your oncologist. If your pet is receiving any medications, it is OK to give the medications in the morning prior to drop-off. If your pet has a specific medical condition such as diabetes, please discuss the timing of medication administration and feeding with a clinician.


Why is my pet shaved?

After the appropriate treatment field is determined, we may clip hair and apply ink marks to outline the treatment field to help guide us in setting up the treatment fields. The marks should not be washed off, so please avoid bathing your pet unless absolutely necessary. It is important that you do not allow your pet to swim as this will wash away the marks as well. 


May I bring my pet's toys, bed, food, etc.?

If you are planning on boarding your pet with us, it is helpful to bring your pet's food. We have a variety of different foods available here, but we may not have your pet's specific type of food. We want to try and keep your pet on its normal diet if possible. You are welcome to bring in your pet's bed and toys; however, please make your pet's items are clearly labeled with your pet's name (first and last). While we make every effort to keep your pet's items with your pet, we do have multiple individuals involved with cleaning, and there are times when things are lost or misplaced. We cannot guarantee that these items will be returned at the time of discharge. If your pet is staying with us during the week and going home on the weekends, we may send home some medications. You should bring these back with you at the beginning of the week.


What happens if my pet has an emergency?

If you think your pet is seriously ill and needs immediate attention, you should either call your local veterinarian or LSU-SVM. Emergency admission to the LSU-SVM will be made by ringing the bell at the doors of the small animal clinic. Emergency technicians, students and a veterinarian are always on duty 24/7, 365 days a year. If you are not sure that you have an emergency, you can call (225) 578-9600. If the hospital is closed, an emergency answering service will take your information and an emergency technician or student will return your call. There is always an oncologist on call, so if the emergency veterinarian cannot answer your questions, they can contact the oncologist. 


Radiation therapy technician

A registered veterinary technician (RVT) is primary responsible for administration of radiation therapy to patients and the delivery of treatments. Shay Bordelon and Katie Montgomery are the radiation technicians and are available to answer any questions or concerns you may have. Shay and Katie will be the ones taking care of your pet while he/she is in the hospital. They can be reached by calling (225) 578-9600.