What is chemotherapy for pets?
Chemotherapy is a treatment used to target and destroy cancer cells in pets, much like it is for humans. It works by interfering with the growth and division of cancer cells, which helps to reduce or control the cancer. The goal of chemotherapy in pets is not just to treat the cancer, but also to maintain a good quality of life while maximizing their longevity after a cancer diagnosis.
Why is chemotherapy necessary?
Chemotherapy may be necessary for various reasons, especially if a cancer is aggressive or has spread (metastasised) or is very likely to spread despite controlling the primary tumour with surgery or radiation therapy. Some cancers are more effectively treated with chemotherapy alone, while others benefit from a combination of treatments. Chemotherapy can help shrink tumours, reduce symptoms, prevent metastasis and improve overall survival in pets diagnosed with cancer. It is often an essential part of the treatment plan for certain cancers, such as lymphoma.
How is chemotherapy administered to pets?
Chemotherapy can be administered in several ways depending on the type of cancer and the drug being used. The most common methods include:
- Intravenous (IV): A needle is inserted into a vein to deliver the chemotherapy directly into the bloodstream.
- Oral chemotherapy: Some medications can be given in pill form, which your veterinarian will guide you on how to administer at home.
- Injections or topical treatments: Certain drugs may be given as injections under the skin or applied topically.
In rare cases, chemotherapy may be administered directly to the tumour, into the peritoneal cavity (the space surrounding the abdominal organs), or into the pleural space (the area surrounding the lungs) to target specific areas where the cancer is located. Another technique called electrochemotherapy involves using electrical pulses to help chemotherapy drugs enter cancer cells more effectively.
What are some common chemotherapy drugs used in pets?
There are several chemotherapy drugs used to treat cancer in pets, including but not limited to:
- Vincristine: Often used to treat lymphoma, leukemia, and certain types of sarcomas.
- Doxorubicin: Effective for a variety of cancers, including lymphoma, sarcomas, and some forms of breast cancer.
- Cyclophosphamide: Typically used in cases of lymphoma and other cancers.
- L-asparaginase: Used primarily in the treatment of lymphoma.
- Vinblastine: Commonly used for treating lymphoma, mast cell tumours, and certain other cancers.
- Carboplatin: Often used for solid tumours such as osteosarcoma, urothelial carcinoma, and tonsillar squamous cell carcinomas.
- Lomustine: Is sometimes used for brain tumours, mast cell tumours, and lymphoma.
- Mitoxantrone: Often used for lymphomas, certain sarcomas, and urothelial carcinoma.
These drugs work in different ways often synergistically with each other and other cancer treatments to kill cancer cells and help manage the disease.
Chemotherapy is often administered in cycles or protocols?
Chemotherapy is often prescribed as a combination of different chemotherapy drugs in a repeating cycle, known as a chemotherapy protocol. These protocols typically involve multiple cycles of chemotherapy, with each cycle consisting of treatment followed by a rest period to allow the pet’s body to recover. The number of cycles may vary depending on the type of cancer and how your pet responds to the treatment.
In some cases, a single-drug protocol may be used, where only one drug is administered for several cycles.
There may also be maintenance protocols, where lower doses of chemotherapy are given after the initial treatment to help prevent cancer recurrence. Some types of chemotherapy are given as a low-dose daily treatment for a prolonged period, which is known as metronomic chemotherapy. This approach may help slow tumour growth and improve the pet’s quality of life with fewer side effects than higher doses of chemotherapy.
What side effects can chemotherapy have on pets?
While chemotherapy can be an effective treatment, it may cause side effects. However, side effects in pets are generally less severe than those in humans, and not all pets experience them. Some of the potential side effects include:
- Decreased appetite: Some pets may not feel like eating at times (usually very temporary), but it’s essential to keep them nourished.
- Mild gastrointestinal upset: Nausea, vomiting, or diarrhoea can occur but are typically mild and managed with supportive care.
- Fatigue or lethargy: Your pet may feel a little more tired than usual.
- Temporary hair loss: Some pets, especially those breed who require haircuts (old English sheep dogs, poodles), may experience hair thinning or loss but the hair grows back on completion of the chemotherapy. Areas clipped of hair maybe slow to regrow until the chemotherapy is completed.
- Low white blood cell or platelet counts: Chemotherapy can cause a drop in these cells, leading to a possible increased risk of infections or bleeding in very rare cases. Regular blood tests are performed to monitor these levels, and appropriate measures are taken as needed.
Additionally, certain chemotherapy drugs may have specific toxicities, such as:
- Heart problems with Doxorubicin: Doxorubicin can cause heart damage if used in high cumulative doses or where there are certain pre-existing heart problems. However, the dose is carefully managed, and we monitor your pet’s heart function closely to minimise this risk.
- Kidney effects with Carboplatin: Carboplatin can have toxic effects on the kidneys, but this is minimised by adjusting the dose and monitoring kidney function during treatment particularly for high risk patients
- Bladder problems with Cyclophosphamide: In rare cases, cyclophosphamide can cause bladder irritation or haemorrhagic cystitis, which can lead to blood in the urine. We take special care to monitor for this and adjust treatment if needed to minimize these risks.
Compared to humans, pets typically experience fewer or milder side effects. We are committed to prioritising your pet’s quality of life throughout chemotherapy. Regular monitoring will be done to ensure your pet’s well-being, and any side effects are managed promptly and effectively.
How common are side effects compared to humans?
Side effects in pets are generally less frequent and less severe than in humans. Pets often tolerate chemotherapy well, and we work closely with pet owners to minimise any discomfort. The goal of chemotherapy at BVSC is always to provide treatment that improves or maintains quality of life while controlling cancer and maximising longevity.
Is chemotherapy the only treatment option for cancer in pets?
At BVSC, chemotherapy is often part of a comprehensive treatment program. While chemotherapy is the main treatment for certain cancers like lymphoma, it is typically combined with other treatments such as:
- Surgery: To remove primary or localised tumours.
- Radiation therapy: To target and destroy or shrink tumours or treat cancer in areas where surgery may not be possible.
Each treatment plan is customised to the individual pet, and our team will work with you to determine the best approach for your pet’s specific cancer and situation.
What should I expect during my pet’s treatment?
Each chemotherapy session will be carefully planned, and we will be with you every step of the way keeping you fully informed and helping you with treatment choices. Your pet will be monitored for any signs of side effects, and we will make adjustments as needed. Most pets tolerate chemotherapy well and continue to enjoy their lives with minimal disruption.
If you have any concerns about your pet’s treatment or care during chemotherapy, don’t hesitate to reach out to our team. We’re here to provide support, answer your questions, and ensure that your pet receives the best possible care.