Paws of Strength

The diagnosis of cancer is stressful for pet parents and the prospect of chemotherapy treatments can be equally difficult. Many pet parents are rightfully concerned about the potential side effects of chemotherapy and certain medicines can be costly with the involvement of multiple visits to the hospital for several weeks or even months.

The journey of healing – when is chemo needed?

Chemotherapy may be used as the sole treatment for certain types of cancers or may be used in combination with other treatment modalities, such as surgery or radiation therapy. Chemotherapy can be recommended for metastatic disease (cancer that has spread to different areas of the body), for tumours occurring at more than one site (multicentric disease, systemic tumours such as leukaemia or lymphoma), or for tumours that cannot be removed surgically (visceral tumours).

In some cases, chemotherapy can be used to shrink large tumours before the surgery, or to eradicate microscopic cancer cells that cannot or have not

been completely removed surgically. For cancers that have a high probability of metastasis early in the course of the disease, chemotherapy can be used after surgery or radiation therapy to help slow down the growth of cancer cells in other parts of the body

The Power of Precision: How Chemotherapy Disrupts Cancer’s Growth

Chemotherapeutic drugs kill cells in the process of growth and division. Individual drugs have different mechanisms of action, such as damaging a cell’s genetic material (DNA) or preventing cells from dividing. Chemotherapeutic drugs are nonspecific – they cannot distinguish between cancer cells and normal cells of the body. All rapidly dividing cells are potentially sensitive to chemotherapy.

Toxicity to normal, rapidly growing, or self-renewing tissues in the body is the reason behind many side effects of chemotherapy. Fortunately, these normal tissues continue to grow and repair themselves and the injury caused by chemotherapy is rarely permanent.

From cells to cure, one step at a time

Compared to humans who receive chemotherapy, pets experience fewer side effects of treatment. Veterinary oncologists use lower doses of drugs, do not combine as many drugs as in human protocols, and often administer drugs at less frequent intervals. The normal tissues of the body that are typically most sensitive to chemotherapy are the intestinal lining, the bone marrow (which makes red and white blood cells and platelets), and the hair follicles. Toxic effects on the gastrointestinal tract are responsible for decreased appetite, nausea, vomiting, and diarrhea.

In most cases, these signs manifest 3 to 5 days post-treatment, however, some side effects can occur earlier than this period or can be prolonged. Most side effects are mild and self-limiting or can be relieved with oral medications given at home. It is uncommon, though possible for animals to experience more severe side effects secondary to chemotherapy, which require hospitalization for more aggressive supportive care.

Suppression of the bone marrow by chemotherapeutic drugs may cause a drop in the white blood cell count, leading to increased susceptibility to infection. The development of a decreased white blood cell counts and fever during chemotherapy treatment is considered an emergency that requires hospitalization for intensive care (typically intravenous fluids and antibiotics). If the white blood cell count is decreased, but your pet is feeling well and does not have a fever, antibiotics may be prescribed as a preventative measure. A decrease in the red blood cell count post-chemotherapy can occur on occasion, particularly with long-term chemotherapy administration, however, this decrease is often mild.

A decrease in the platelet count can also occur secondary to chemotherapy. Certain drugs affect the platelet count more than others. A markedly low platelet count can put an animal at risk for spontaneous bleeding; however, this complication is rarely secondary to chemotherapy. Bloodwork (complete blood count with blood smear exam) is obtained regularly during the treatment protocol and before chemotherapy administration to ensure it is safe to proceed with treatment and to inform any dose adjustments that need to be made. Hair follicle cells in non-shedding dogs may be particularly susceptible to chemotherapy. Certain breeds of dogs, such as terriers and poodles, will experience variable amounts of hair loss which is most evident on the face and the tail.

The science of healing

The route and frequency of administration of chemotherapy drugs are variable. Certain drugs are oral medications (pills or capsules) that are given at home. Others are injections (intravenously) that require an outpatient appointment for administration. In some instances, slow infusions are given that may require your pet to spend the day in the hospital. Treatments are typically repeated weekly to every few weeks. The duration of treatment depends upon the type of cancer and the extent of the disease. Some pets receive chemotherapy for the remainder of their lives, while in others, treatment may eventually be spread out or discontinued after some time, provided that their cancer is well-controlled. Chemotherapy can also be reinstituted in pets that experience relapse (recurrence) of their cancer post-surgery.

Making technological breakthroughs with Personalized Prediction Profile

Oncopathologist have developed their lab to go further than just identifying the type of cancer that your pet has. They have the added option of our Personalized Prediction Profile, which includes a chemotherapeutic drug response prediction. This provides a personalized prediction profile that shows how the treatment will impact your pet, as well as their predicted time frame of relapse.

The prediction allows us to inform both you and your vet what the best route of action would be, as well as what the outcomes are likely to be based on cellular response to our tests combined with artificial intelligence.

(Dr. Ankur Narad – MVSc, PhD scholar (Chief Veterinarian, RGCN PET CLINIC) Bhopal, M.P.; Dr. Supriya Shukla, PhD, Prof & Head Dept of Vet Pathology and Disease Investigation Lab; Dr. Reshma Jain, PhD, Associate Prof (Vet Surgery); Dr. Urvashi Choudhary, MVSc, scholar (Vet Surgery) – Veterinary College, Mhow)