Just as Cancer has become a common illness in people, it is now the most common cause of pets not enjoying their full life expectancy. The good news is that modern advances in treatment means that pets can live longer with cancer and have better outcomes when they are diagnosed. Eltham Veterinary Practice has been offering chemotherapy for many years now. Cancer in animals is always a serious disease and treatment commonly involves a variety of modalities including surgery, radiation and chemotherapy – either alone or in combination. Chemotherapy is commonly used in cancers if the risk of metastases (spread) cannot be treated with surgery alone, if there are residual cancer cells left after surgery, or when it may enhance the effectiveness of other treatments.
What is chemotherapy?
Chemotherapy is the administration of drugs designed to kill or slow the growth of cancer. Chemotherapy can be administered to the patient as an injection or as an oral medication. Chemotherapy drugs circulate throughout the entire body blocking cell growth and division. The goal of chemotherapy in pets is to control or eliminate cancer while still maintaining the highest quality of life. The drugs we use to treat animals are the same drugs used to treat people with cancer. Our aim is often to improve quality of life and ideally achieve remission, rather than a complete cure. This means the doses of chemotherapy drugs are lower in animals than in people as we tend to treat them less aggressively. For this reason animals usually do not suffer the same degree of side effects, if they experience any at all.
Approximately 70–80% of patients on chemotherapy have minimal to no side effects. Of those that experience side effects, these are usually mild, short lived and may resolve without treatment. Cancer is composed of active, dividing and multiplying cells and these are the cells that chemotherapy targets. There are some normal cells in the body that are also actively dividing and therefore they can also be affected by chemotherapy. These cells are found in the blood and bone marrow, gastrointestinal (digestive) tract, skin and reproductive system. Consequently, potential side effects include decreased appetite, nausea, vomiting, diarrhoea and infection. Patients may be more susceptible to infections if there is a significant decrease in the white blood cell count. Alopecia or hair loss that is commonly seen in humans is uncommon in dogs. It is seen most often in breeds that have continuously growing hair (i.e. Poodles, English Sheepdogs). Cats generally do not lose body hair, but can lose their whiskers. Chemotherapy can also slow regrowth of hair.
Although the above are the most common potential side effects, it should be remembered that the majority of patients have minimal to no side effects.
How is chemotherapy administered?
While some of the drugs can be given orally at home, most are given by injection at the veterinary hospital. For all chemotherapy treatments, our staff wear appropriate protective clothing and we work as a team to minimise the time a patient will spend with us. Each patient receives a thorough physical examination and a haemogram (blood test to ensure the blood cell counts are adequate for treatment). An intravenous catheter is placed for safe administration of chemotherapy. After administration, the catheter is removed and a light bandage is placed, this can be removed after 1–2 hours. In all, the entire process takes a few hours.
Is there any risk to me?
Potentially – although there have been no studies done to prove this. Most of the chemotherapy drugs we use leave the system through faeces, urine or saliva and they could possibly be a risk to you if you come in contact with them within 48 hours of treatment. It is important to wear gloves if any accidents occur inside your home, clean the area with disposable items (i.e. paper towel) and wash your hands thoroughly afterwards. If toileting is done outside, simply leave faeces for 48 hours before collecting it. The ultraviolet light in the sun will often deactivate any potential residues in the faeces. In general, it is recommended that if clothing/ bedding is soiled by faeces, urine or vomitus within 48 hours of chemotherapy it should be washed twice in hot water or thrown out.
How do I chose what is best?
Chemotherapy is aimed to provide disease free time for your pet and to maintain a good quality of life. No one can accurately predict how long this will be. For some cancers, there is more information available and we can sometimes give you an estimation of what you might expect. Chemotherapy involves commitment and dedication as it may need daily, weekly or monthly administration of medication, with no guarantee of success. During treatment, several crisis points can occur. There may be failure to respond, recurrence of the growth or complications of the cancer or treatment (sometimes unexpected death). Thus, it is understandable that some owners elect euthanasia when their pet is diagnosed with cancer.