Will chemotherapy make my pet sick?
When discussing chemotherapy with clients, concerns about side effects are by far the most common, and understandably so. Human chemotherapy patients often endure significant challenges during their treatment, so it’s natural to assume that dogs and cats might face similar experiences.
As veterinary oncologists, our approach to chemotherapy for pets is different from what you might expect. In human medicine, high doses of chemotherapy are used to aggressively attack cancer cells. In contrast, our first priority in veterinary medicine is preserving the quality of life for our patients. Therefore, chemotherapy for cats and dogs is carefully calibrated to minimise adverse effects while maximising its anti-cancer effects.
What Are the Side Effects?
Chemotherapy works by destroying actively dividing cells, which is a feature of cancer. However, it also affects healthy cells that naturally divide rapidly in certain parts of the body, leading to some collateral damage. This is why chemotherapy can sometimes make patients feel unwell.
The Gastrointestinal System: The lining of the stomach and intestines is constantly renewing itself. When chemotherapy affects these cells, it can lead to nausea. It’s important to remember that just because a veterinary patient isn’t vomiting, it doesn’t mean they aren’t feeling nauseous. Signs of nausea can be subtle, such as being slower to finish meals or appearing quieter than usual. Fortunately, anti-nausea medications can effectively ease these symptoms, allowing your pet to receive higher doses of treatment without a negative impact on their well-being.
The Bone Marrow: This is where red and white blood cells are produced. If chemotherapy affects the bone marrow, it can lead to anaemia, infection, or blood clotting abnormalities. Often, these issues don’t show obvious symptoms, so regular blood tests are performed to monitor blood cell levels. It’s crucial to ensure that a patient has a healthy blood cell count before administering chemotherapy, which is why a blood count test is conducted prior to each treatment.
Fur: The good news is that it’s rare for a dog or cat undergoing chemotherapy to lose all their fur. Unlike human hair, animal hair follicles typically aren’t constantly dividing. While some breeds might look a bit thinner in areas with friction, such as under collars or harnesses, it’s highly unusual for them to lose all their fur.
While chemotherapy does carry some risks of side effects, they are unusual as a result of our approach to minimise these as much as possible. We prioritise your pet's comfort and quality of life, and with careful monitoring and supportive care, most pets continue to enjoy life during and after treatment.