Radiation Therapy for Pets: Which Cancers Are Treated and What to Expect

What is radiation therapy for dogs and cats?

Radiation therapy is a targeted cancer treatment that uses controlled doses of ionising radiation to destroy tumour cells or slow their growth in dogs and cats. It is used alone or alongside surgery and chemotherapy. MaxPetz in Delhi offers cancer care for pets, including guidance on radiation therapy options for dogs and cats diagnosed with cancer.

Radiation works by damaging the DNA of rapidly dividing cancer cells, preventing them from reproducing. Because it can be precisely directed, it is particularly useful for tumours that are difficult to remove surgically or that have not been fully excised.

Which pet cancers respond best to radiation therapy?

Not all cancers respond equally to radiation. The following tumour types in dogs and cats are commonly considered for radiotherapy, either as a primary treatment or as part of a combined approach:

The oncology team will stage the cancer and assess tumour location, size, and spread before recommending radiation as part of the treatment plan.

How many radiation sessions does a pet need and what does the process involve?

The number of sessions depends on the treatment goal — curative or palliative — and the tumour type. A typical course is structured as follows:

1. Oncology consultation and staging: Blood work, imaging (CT or MRI), and biopsy results are reviewed to confirm the diagnosis and plan the radiation field.
2. Treatment planning (simulation): A CT scan is taken with the pet in the exact treatment position. Software maps the radiation dose to the tumour while sparing surrounding healthy tissue.
3. Anaesthesia for each session: Pets cannot remain still voluntarily for the precision required. A short general anaesthetic is administered for every fraction. Sessions typically last 15–30 minutes including anaesthesia induction and recovery.
4. Fractionated delivery: Curative protocols commonly involve 16–20 daily fractions (Monday to Friday) over 3–4 weeks. Palliative protocols use fewer, larger fractions — often 4–6 sessions over 2–3 weeks — to manage pain and slow progression.
5. Monitoring and follow-up: Response is assessed with imaging at defined intervals after the course ends.

What are the side effects of radiation therapy in dogs and cats?

Side effects depend on the area being treated, the total dose, and the number of fractions. They are broadly divided into acute (during or shortly after treatment) and late (weeks to months after completion).

Acute side effects (typically resolve within 2–4 weeks of completing treatment):

• Skin redness, hair loss, or moist desquamation in the treated area
• Mucositis (mouth sores) when oral or nasal regions are irradiated
• Mild lethargy following each anaesthetic episode
• Eye irritation if the radiation field is near the orbit

Late side effects (less common but potentially permanent):

• Fibrosis or scarring of soft tissue in the treated zone
• Bone changes (osteoradionecrosis) in rare cases involving skeletal structures
• Cataract formation if the lens receives significant dose
• Neurological changes if the spinal cord or brain is in the treatment field

When should you consult a veterinary oncologist about radiation therapy?

Seek a specialist oncology consultation promptly if your pet has been diagnosed with cancer or shows any of the following signs for more than 7–10 days:

• A lump or swelling that is growing, changing shape, or not resolving after 4 weeks
• Persistent nosebleeds or nasal discharge from one nostril
• Difficulty eating, swallowing, or opening the mouth
• Unexplained weight loss of more than 10% body weight over 4–6 weeks
• Neurological signs such as seizures, head tilting, or loss of coordination
• A surgical pathology report indicating incomplete tumour margins
• A biopsy confirming a tumour type known to respond to radiation (e.g. nasal carcinoma, mast cell tumour, soft tissue sarcoma)

Early referral allows more treatment options to be considered and may improve the outcome of the overall cancer management plan.

How does MaxPetz Delhi support pets undergoing cancer treatment?

MaxPetz in Delhi provides cancer care for dogs and cats with a focus on cutting-edge veterinary technology and compassionate, individualised support for each patient and their family. The team coordinates diagnostics, oncology referrals, and supportive care — including pain management, nutritional guidance, and monitoring — so that pet owners have a consistent clinical point of contact throughout the treatment journey.

For pets undergoing radiation therapy at a specialist centre, MaxPetz Delhi can assist with:

• Pre-treatment workup including blood panels and imaging coordination
• Supportive care management between radiation fractions
• Wound and skin care for acute radiation reactions
• Post-treatment monitoring and follow-up imaging
• Palliative and quality-of-life care when curative treatment is not pursued

To discuss your pet's diagnosis and explore whether radiation therapy is appropriate, use the cancer care booking form on this page or speak with the team directly. You can also learn more about pet oncology consultations and our veterinary diagnostics services.