Radiotherapy for dogs and cats

Conventional radiotherapy includes different radiation techniques, more or less complex, distributed in “standard” doses that aim to cover both the target lesion and nearby microscopic margins. These treatments are typically carried out in 4 to 20 sessions, depending on the treatment goal.

Electron therapy

Electron therapy uses a type of radiation (electrons) whose energy will be deposited on the surface, without deep irradiation. This type of treatment is indicated in the case of superficial tumours (skin or subcutaneous), especially if organs at risk are present under the treated target (e.g. chest or abdominal wall). In the latter case, there will not only be an optimal dose on the surface, but an optimized avoidance of healthy tissues in depth.

Photon treatment and 3D conformal technique

A majority of deeper or complex shaped lesions (or targets) will be more ideally treated by photon therapy (X-rays). The treatment plan will then be more or less complex, depending on the location of the lesion and the proximity of tissues at risk. A simple 3D conformal treatment is suitable for the treatment of target volume lesions without proximity to particularly at-risk organs or some wide-field techniques, or the implementation of low-intensity, palliative treatment.

• Mandibular tumours
• Complex subcutaneous tumours (limbs)
• Bone tumours (palliative)
• Multicentric or abdominal lymphomas
• Meningitis of unknown origin

IMRT or VMAT treatment

When greater precision is required, particularly for target dose optimization and/or avoidance of organs at risk, dose-modulated treatment techniques (IMRT or VMAT) are indicated. These high precision techniques require greater quality controls to ensure perfect treatment delivery. The greater precision allows in some cases to reduce the number of sessions without compromising the quality of the therapy (hypofractionation).

• Nasal or maxillary tumours
• Cervical tumours
• Brain, pituitary or spinal tumours
• Intra-thoracic tumours (thymoma, tumours of the base of the heart, etc.)
• Intra-abdominal tumours (adrenal tumours, bladder, urethral or prostate tumours, anal sac tumours, etc.)

In some very specific cases (early stages of some pathologies), a new technique with very high dose conformation makes it possible to reduce protocols to only 1 to 5 consecutive sessions. This approach is definitive and uses “ablative” doses of radiation. At these doses, only the target lesion is exposed and healthy tissues beyond 1-3 mm from the lesion must be spared, at the risk of local complications. This technique is based on very complex planning and very restrictive quality control procedures in order to ensure maximum safety for these patients.

• Nasal tumours
• Brain, pituitary or spinal tumours
• Bone tumours
• Other indications currently being validated

The care pathway begins with a consultation in medical oncology or radiation oncology for case assessment and validation of the indication after diagnosis and extension assessment. During this consultation, the prognoses, protocol options, often multiple, and logistical and financial aspects are discussed.