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Chemotherapy
For many people, the word chemotherapy brings up negative images. But there are many differences between how pets with cancer and people with cancer are treated. It is important to understand that our goal is for pets undergoing chemotherapy to have NO side effects from treatment. We work towards this goal by carefully choosing drugs and dosages, administering supportive drugs during treatment, and by educating owners about “at-home” care.
Pets undergoing treatment for cancer need lots of love and attention. Your pet may even bond with the veterinary staff due to the extra attention they will receive during their appointments.
Chemotherapy is typically administered by injection into veins, under the skin, or into the tumor. Some chemotherapy is also given in pill form. How chemotherapy is given depends on your pet’s specific medical needs and we are happy to discuss all your options at your appointment.
Chemotherapy administration
Injectable chemotherapy agents may be given intravenously (IV), subcutaneously (SQ, under the skin), or intralesionally (IL, into the tumor or site of tumor excision).
IV chemotherapy is the most common. The majority of IV chemotherapy treatments require no sedation and the treatment itself takes less than 30 minutes. Many pets will even eat treats during their chemotherapy treatments!
Oral chemotherapy is given at home and can vary greatly in quantity and frequency. Some protocols require only one pill every 3 – 4 weeks, while others require daily administration. Your oncologist can give you all the possible treatment options at your appointment.
Intralesional chemotherapy is the direct injection of chemotherapy into a tumor or the site of tumor excision. Tumors may be reduced in size, become less painful, and may even be cured with intralesional chemotherapy alone. This treatment is currently under investigation by Veterinary Cancer Care to treat a variety of tumors. Much of this research is in the process of being published.
Potential side effects of chemotherapy
All side effects should be monitored closely and treated immediately.
Gastrointestinal side effects
Gastrointestinal side effects are the most common side effect we see, and they are the most easily treated with at-home medications. Side effects can include:
* Nausea (symptoms can be eating grass, lip smacking, drooling, and food aversion)
* Vomiting
* Diarrhea (with or with blood or mucous)
* Anorexia (loss of appetite)
* Colitis (blood or mucous in stool, or straining to defecate)
Bone Marrow Suppression
* Neutropenia – a low white blood cell count. This can be a very serious, life threatening side effect.
* Anemia – a low red blood cell count. This side effect may cause your pet to feel lethargic. Feeding your pet red meat and liver can help them to have increased energy.
* Thrombocytopenia – a low platelet count. This affects your pet’s ability to clot blood. Your pet may bruise or bleed (usually nose bleeds) without cause.
Hair loss (Alopecia)
Hair loss is a very rare side effect except in dogs that have continuously growing hair. The hair should grow back when chemotherapy is completed. Many animals, cats and dogs, will lose their whiskers.
Side effects can occur immediately or days after treatment. With supportive care, side effects should resolve immediately. If side effects are not addressed, they can be fatal.
If your pet has side effects
Do not wait and see; your pet should be seen by us, your primary veterinarian, or an emergency clinic. A CBC (complete blood count) should be run to determine your pet’s white blood cell count.
Fever
This is an emergency and your pet needs immediate treatment. Standard treatment is obtaining a CBC, hospitalization, IV fluids, IV antibiotics, and other supportive care.
Diarrhea
If the diarrhea is mild and lasts less than 24 hours give your pet small, frequent meals of a bland diet, such as boiled chicken and white rice. If there is scant blood and/or mucous in the stool (colitis), add fiber. Severe diarrhea lasts longer than 24 hours and is an emergency.
Vomiting
If the vomiting is mild and lasts less than 8 hours and your pet has NO other health problems, such as kidney disease or diabetes then hold food and water for a few hours. Begin by introducing water only, in small amounts for the first 12 hours. Then add small, frequent feedings of a bland diet with a gradual increase in quantity. Severe or extended vomiting is an emergency.
For more information about chemotherapy:
Please visit the United States National Library of Medicine/National Institute of Health’s website. Search their database for specific drug information.
