Radiation Therapy

Our beloved pets are living longer, healthier and better lives than many years ago.This is thanks to owner’s approach to care of their pets. As our pets reach this ripe old age veterinarians are often required to intervene with their medical problems. Our older pets are often seen with various ailments: renal failure, cardiac insufficiency and cancers to name a few. Some cancers are benign and others are malignant.

The approach to cancer treatment in the patient is based on achieving a good quality of life for as long as possible and not necessarily to attempt to “treat and save at all costs”. We do not want the treatment to be worse than the cancer itself.

Tumour eradication uses multiple disciplines -surgery, chemotherapy and radiation therapy are either used alone or more often in combination. The type of cancer your pet has and where in the body the cancer is located will affect the choice of modality that the veterinarian will ultimately choose to treat the cancer.

Radiation therapy is often used for large inoperable tumours that occur locally. The goal of radiation therapy is to destroy the reproductive capacity of the tumour without excessivey damaging the surrounding normal tissues. Radiation may also be used as palliative therapy for the relief of discomfort.

Radiation treatment is usually given as multiple small doses 1 day per week over a 4-6 week period. Each treatment requires approx 10-30min of radiation. A short acting sedative or anaesthetic is given to keep your pet still during the procedure. Mild to moderate weight loss may be seen in patients receiving radiation, especially if the mouth or nose is treated.Tumours do not necessarily shrink rapidly and it may take months for it to decrease in size. Certain risks and side effects are encountered with radiation. Fortunately side effects are restricted to the region of the body being treated for the tumour.These side effects fortunately only persist for a limited period of time

Examples of tumours often treated are oral melanomas, nasal passage tumours, brain tumours and tumours of the trunk and extremities eg. sarcomas (osteoarcomas, fibrosarcomas)and mast cell tumours. The survival times post radiation depends on several factors, the tumour type, distant metastasis and other concurrent disease. For examples dogs with Brain tumours have a survival post radiation of around two years and nasal tumour about one year.
Palliative radiation is mainly used to control pain in osteosarcomas and improve the pets quality of life. Osteoarcomas are very aggressive tumours and these patients mean survival period is approximately four months post radiation.

Allthough radiation therapy may not provide complete remission, in many cases it has become an important tool either as the main therapy or as an additional therapy in a multi-treatment approach of cancer in our beloved pets.