Many senior pets eventually succumb to cancer. In fact, cancer is responsible for nearly 50% of canine deaths each year, with likely many more remaining undiagnosed. Cancer is so common that understanding the disease to the fullest extent is paramount to providing your pet with the best prognosis and quality of life after diagnosis. To achieve this goal, your pet’s cancer is generally staged and graded, granting you more information and allowing you to make the best treatment decisions for your pet.
What are the cancer stages in pets?
Essentially, stage refers to where in the body cancer evidence is found. Cancer stages in pets determine if a particular type of cancer has spread, which helps solidify a prognosis of your pet’s condition. Cancer grading may also determine how aggressive a cancer is and how quickly it will grow and spread. Cancer staging is one of the most helpful indicators for determining the most effective treatment against a cancer type.
Unfortunately, no veterinary governing body has established guidelines for staging disease, as the World Health Organization (WHO) does in human medicine. Instead, veterinary medicine models many of the common cancers in dogs and cats on human staging guidelines.
One of the best examples for staging cancer in pets is the lymphoma model:
* Stage 1 — Single lymph node affected on one side of the diaphragm
* Stage 2 — Multiple lymph nodes affected on one side of the diaphragm
* Stage 3 — Multiple lymph nodes affected on both sides of the diaphragm
* Stage 4 — Liver and/or spleen involvement with lymph node involvement
* Stage 5 — Extra-nodal involvement (e.g., bone marrow, peripheral blood, skin, or eyes)
To determine your pet’s cancer stage, many diagnostic tests are necessary to help plot the best treatment course and most accurate prognosis.
How is my pet’s cancer stage determined?
Diagnostic testing for cancer staging in pets can be extensive, but it helps provide the most accurate prognosis and guides the treatment plan. If your pet has been diagnosed with cancer and your veterinary oncologist recommends staging the disease, they may recommend the following tests:
* Complete blood count — A complete blood count (CBC) quantifies your pet’s red blood cells, white blood cells, and platelets. Blood cell and platelet counts can indicate anemia, infection, cancer, dehydration, and clotting issues.
* Blood chemistry panel — A blood chemistry panel provides information about your pet’s organ function, namely the kidneys and liver. Also, it measures your pet’s glucose level and the level of various electrolytes needed for various bodily functions.
* Fine-needle aspirate — A fine needle aspirate (FNA) is one of the most common first steps for a tissue sample of the suspected cancerous mass. Performing an FNA involves inserting a needle and syringe into the mass and pulling back on the syringe’s plunger to create suction. As the syringe creates negative pressure, a small volume of cells is aspirated into the syringe, which is then placed onto a slide for microscopic evaluation.
* Biopsy — Performing a biopsy is more invasive than an FNA and requires greater pain relief and immobilization. Once your pet is sedated or anesthetized, the veterinarian will use a scalpel blade or biopsy instrument to cut into the mass and remove a small sample, known as an incisional biopsy. Or, they may remove the mass entirely by performing an excisional biopsy. In some cases, performing an excisional biopsy cures the cancer.
* Radiographs — Since many cancers are highly aggressive and can quickly metastasize, survey X-rays are recommended to check for chest or abdomen metastases.
* Ultrasound — An abdominal or thoracic ultrasound can check for lymph node size and potential metastasis and serve as a guide for sampling the liver and spleen.
* Bone marrow aspirate or biopsy — Taking a bone marrow sample can aid in diagnosing and evaluating certain cancers that affect the bone marrow.
If your pet develops cancer, staging is vital to the overall management and treatment plan. Staging can help determine your pet’s prognosis, allowing you to make a more informed decision about hospice care and in-home euthanasia.
Additional blog posts about cancer in pets:
My Pet Was Diagnosed with Cancer: What to Expect
How to Care for Your Pet with Cancer
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