In animals, chemotherapy often has a somewhat different aim than in people. The priority is the patient’s quality of life – drug doses are chosen to control the disease with as few side effects as possible. The vast majority of dogs and cats tolerate treatment very well.
When is chemotherapy used?
- In systemic cancers, such as lymphoma and leukaemias – here chemotherapy is the main treatment (see the stories of Teddy and Mruczek). In dogs with lymphoma that have achieved remission, treatment can be supplemented with half-body irradiation (HBI).
- After surgery (adjuvant treatment) – when the cancer carries a high risk of metastasis, as in Ciri after removal of a kidney with a Wilms tumour.
- Before surgery (neoadjuvant treatment) – to shrink a tumour and make it possible to remove it; this was the case for Edek, whose chemotherapy reduced a tumour at the base of the tongue.
- Palliatively – when a cure is not possible and the aim is to slow the disease and keep the patient comfortable (Czaruś).
What does treatment involve?
Chemotherapy follows a protocol – a planned schedule of drugs and the intervals between them. Drugs are given intravenously (as a short infusion) or by mouth, and visits are usually every 1–3 weeks. The animal goes home the same day – no hospital stay is needed.
A blood test (complete blood count) is done before every dose – ideally no earlier than 24 hours before the visit. This allows us to assess the bone marrow and safely clear the patient for the next dose. You can read more about preparation in the FAQ.
How do animals tolerate chemotherapy?
Side effects occur in a minority of patients and are usually mild and temporary. They most often affect the digestive tract (reduced appetite, vomiting, diarrhoea) and cause a temporary drop in white blood cell count. Hair loss is uncommon in most animals – it may affect dogs of breeds with continuously growing coats (e.g. poodles), and in cats the loss of whiskers.
If worrying symptoms appear after a dose, contact the treating veterinarian. Treatment can always be modified: the dose can be reduced, supportive medication added, the protocol changed, or treatment stopped.
Is chemotherapy safe for the people in the household?
Yes – a pet undergoing chemotherapy can be stroked and cuddled as usual. For a few days after a dose, however, extra care is needed when cleaning up urine, faeces and vomit (gloves, a sealed bag), and pregnant women and small children should avoid contact with the animal’s excreta. You will find detailed guidance in the FAQ.
Targeted drugs
Besides classic cytotoxic drugs, veterinary oncology uses targeted drugs, for example toceranib – an oral tyrosine kinase inhibitor that slows the growth of cancer cells and the formation of blood vessels in the tumour. It formed part of the treatment of Pele and Borys.
A newer drug, developed specifically for lymphoma in dogs, is rabacfosadine (trade name Tanovea).