The Big ‘C’: Cancer, Chemotherapy, and Your Pet
Finding out your pet has cancer is one of the hardest moments for any pet parent. And it's a moment that almost all pet parents will experience. Cancer is the leading cause of death in dogs and the third most common cause of death in cats.
Luckily, veterinary medicine academic institutions and independent organizations like the Animal Cancer Foundation and the Canine Cancer Alliance continue research to provide treatment and cures for our loved ones.
The Diagnosis
Most cancer diagnoses are made by a primary veterinarian. When pets are feeling off, begin to limp, have new lumps or bumps, or through routine testing, a general practitioner is the first to help. Families can start with their primary or emergency veterinarian for examination and testing, or can get recommendations or referrals for testing. To check concerns, starting with a routine appointment or emergency visit to have the pet assessed and start diagnostic testing.
Diagnosis of cancer can be achieved with:
blood or urine testing
fine-needle aspirates, or using a needle to collect a small sample of cells from a tumor or organ that is then assessed microscopically (cytology)
biopsy, or the collection of a larger piece of tissue via a small surgery (incisional biopsy) or complete removal of a tumor or organ for submission (excisional biopsy)
imaging, including magnetic resonance imaging (MRI), computed tomography (CT), ultrasonography (aka sonogram), or radiographs (x-rays)
In some cases, a referral to a specialist—such as an internal medicine specialist—may be needed for a definitive (confirmed) diagnosis. And rarely, if a pet does not have a definitive diagnosis because it cannot be achieved after testing, it may be recommended to start treatment. By monitoring the pet’s response to a treatment, a definitive diagnosis can sometimes be confirmed.
Most veterinary oncologists prefer a diagnosis before consultation, although some chemotherapies can be prescribed or administered with a primary veterinarian alone.
The Treatment
Many pet cancers have treatment options that can include surgical or medical interventions. Once a diagnosis is made, next steps should be considered with the pet’s comfort in mind. Tumors are often surgically removed. If possible, they are removed completely, or they remove as much of the tumor as possible, before pursuing further treatment. Other cancers like blood cancers, inoperable tumors, or cancer affecting a large area of the body require other treatment options.
Chemotherapy is the treatment of cancer with drugs used to target, then kill or slow the growth of cancer cells. This can include oral or injectable medications, direct tumor or organ infusions, or topical treatments.
Chemotherapy is often paired with surgery, radiation, and palliative care for best outcomes. Studies measure the success of treatment as median survival time (MST). MST is the length of time from diagnosis or start of treatment at which exactly 50% of a patient group is still alive. However, the pet’s care team should consider other parameters when considering the success of treatment including severity and duration of symptoms the pet will experience, current and anticipated quality of life, and outcomes of treatment (i.e. amputation, loss of vision, etc.).
According to Jillian Walz, DACVIM (Oncology), DACVR (Radiation Oncology), “our patients' blood work is monitored very carefully with blood tests to ensure that they have an adequate number of white blood cells. We learn much from the first month of chemotherapy. If dogs do not become ill from the first few treatments, most sail through the rest of treatment without significant problems.” And this also applies to cats receiving chemotherapy.
If side effects occur and treatment is not tolerated, it can be adjusted or changed to ensure the pet’s comfort and safety, while maximizing their quality of life.
The Symptoms
Although chemotherapy can sound intimidating, the majority of pets tolerate it well. Because chemotherapy targets rapidly growing cells in the body in order for it to preferentially attack cancer cells, it will still affect some of the body's more rapidly growing cells, mainly the gastrointestinal cells and the white blood cells in the bone marrow.
The majority of dogs (70–80%) will not experience any side effects with chemotherapy. About 20–25% of dogs may experience side effects, the most of which are relatively mild and easily managed. The most common signs are vomiting, nausea, diarrhea, and decreased appetite. Less than 5% of dogs may experience severe side effects that could require hospitalization.
Palliative Care
Palliative care is the management of a disease, curable or incurable, with a focus on managing pain and other factors negatively impacting quality-of-life.
Palliative care can include curable short-term diseases to terminal illness requiring end-of-life care which means that all cancer diagnoses can be paired with palliative care.
Consider working with your veterinarian to create a ‘chemo kit’ if you are pursuing cancer treatment for your pet. This can include treatments for common symptoms including anti-nausea medication for vomiting, antidiarrheal medication for diarrhea, mild sedatives for vet visits, subcutaneous fluids to keep your pet hydrated, and a thermometer to test their temperature when feeling unwell.
It is important to remember, if your pet is experiencing any side effects from chemotherapy, contact your veterinarian immediately or seek care.
If your pet has a recent diagnosis of cancer, it can be overwhelming to figure out next steps and what works best for your pet. You can reach out at hello@gentlejourneyvetcare.com. We can help discuss cancer treatment options including chemotherapy and palliative care and make a customized care plan for your pet together.
