Chemotherapy and your pet


Why Should I Bring my Pet to Willows for Chemotherapy?

Willows is one the UKs only referral centres to have full-time, internationally renowned Specialists in both Medical and Surgical Oncology. This, combined with a multi-disciplinary approach to the management of pets with cancer, enables Willows to provide the best possible levels of care for your pet.

Our Oncologists are supported by our multi-disciplinary team of Specialist including Diagnostic Imaging, Anaesthesia and Analgesia Specialists. Willows also has a large dedicated team of Vets, Nurses and clinical support staff available 24 hours a day, every day of the year to provide the best possible care for your pet.


What is Chemotherapy?

Chemotherapy is the treatment of cancer through the use of drugs. It can also be used in conjunction with surgery and/or radiation treatment, and has proven helpful in the treatment of several different types of cancer in dogs and cats.

Chemotherapy aims to prolong the life if a pet, and more importantly to maintain a good quality of life for whilst undergoing treatment for cancer. Similar drugs to those used in human oncology are given to animals, however the high doses used in human patients are not generally administered to pets. As such, the side effects that animals experience are therefore significantly reduced and/or hopefully non-existent.

How does Chemotherapy Work?

Cancer can generally be defined as a rapid, uncontrolled growth of cells. Anti-cancer drugs interfere with the ability of cells to grow and multiply. These drugs cannot usually distinguish between cancer cells and normal body cells. As a result normal cells, especially those found in the bone marrow and gastrointestinal tract, can unfortunately also be affected. Despite this, most normal cells are better able to recover and repair themselves than cancer cells.

For widespread tumours, drugs are used to provide a total body effect, this is known as systemic chemotherapy. In many cases, a combination of different drugs working in different ways is the most effective way to kill the cancer cells.

Most anti-cancer drugs are given by mouth or by injection. Some drugs need to be injected into a vein while others can be injected into the muscle or under the skin.


How long will My Pet Receive Chemotherapy for?

The length of time and frequency of drug administration will depend on the type of cancer and how well the treatment is tolerated. Treatment may be given daily, weekly or monthly, often the time between treatments is tailored to the individual patient. Treatment may be given in cycles which include rest periods, allowing patients’ time to build healthy new cells.

chemo landscape

As a Pet Owner am I at Risk of Exposure to these Drugs?

  • It is important that capsules or pills are kept out of reach of children, in child-proof containers. Most oral drugs have a protective coating, disposable gloves should be worn when handling these medications and tablets/capsules must never be split.
  • It is important to avoid unnecessary contact with the urine and faeces of animals receiving chemotherapy, especially for the first week after the drug is given (this really just involves normal sensible hygiene precautions). If your dog or cat has an accident in the house, wear gloves to clean it up – cat litter can be a useful absorbent material to use on urine. Then thoroughly rinse the exposed surface after the waste is cleaned off.

Will my Pet Experience any side Effects?

The Specialist treating your pet will always try to choose the drug doses and combinations likely to cause the least number of side effects while giving the best therapeutic advantage possible. Steroid drugs often have a role in cancer treatment protocols and may be given at high doses in the early stages of treatment. Noticeable side effects may include your pet drinking more, and so they will need free access to water and frequent opportunities to urinate. Their appetite often increases and some dogs will appear to puff and pant a bit more. These side effects are mild, reversible and improve as the dose reduces.

Please observe your pet closely during treatment and call us if you feel he/she seems ill. Your pet may need to be seen by Willows or your local Vet (or their emergency service) if there are any severe side effects.


What are the Side Effects of Chemotherapy?


Most pets with a high temperature are miserable and refuse to eat. If your pet is depressed, has a fever or blood in the faeces, it may be necessary to start treatment with antibiotics and/or intravenous fluids (i.e. a drip). Once your pet starts antibiotics, the full course prescribed must be completed, even if the situation improves rapidly, as it often will.

Hair loss
Heart disease

Please talk to us about your concerns

This list of potential side effects of chemotherapy can appear very alarming, however it is important to realise that this includes all the common side effects of a variety of drugs used to treat many different tumours.

We hope that your pet will feel well throughout chemotherapy, or only experience feeling a little ‘off-colour’ (loss of appetite, slight nausea) on the day after treatment, but no more.

Each patient responds differently, and so the dosage of treatment will be adjusted to give the best chance of the cancer responding to therapy, whilst at the same time keeping the patient feeling as well as possible. This means that we have a ‘starting point’, or a drug dose that most patients tolerate well, however if you feel that your pet is unwell during treatment talk to us and in many cases we can use a lower dose of drug, or even change the type of drug, to make them feel better.

Every individual is different and we rely on you the owner, who knows your pet best, to let us know if you are not happy with how they are doing.

Reference Hayes, A. (2005) Safe use of anti cancer chemotherapy in small animal practice. In Practice, 27, 118-127

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