When your pet is diagnosed with cancer, you might feel as if you’re having to learn a whole new language. This post provides definitions of some of the most common terms you’ll hear during diagnosis and treatment. Please remember, your veterinary oncology team will be happy to answer your questions, but this article serves as a useful reference and reminder.

Common Types of Cancer in Companion Animals 

Hemangiosarcoma – A cancerous tumor made up of blood vessels that typically occurs in the spleen or right atrium of the heart

– A cancerous tumor of lymphoid tissue

Mast Cell Tumors (MCT)
– A cancerous tumor of mast cells (a type of inflammatory cell). Mast cell tumors can involve the skin, subcutaneous tissue, muscle tissue, as well as lymph nodes and other organs

– A cancerous tumor that begins in melanocytes (cells that make the pigment melanin)

– A cancerous tumor of the bone that usually affects the long bones of the arm or leg

Soft Tissue Sarcoma (STS)
– A form of cancer that develops in mesenchymal tissue: the muscle, connective tissues, and bones of the body.

TCC (Transitional Cell Carcinoma)
– A cancerous tumor of transitional epithelial origin usually associated with the bladder

Diagnostic Testing

Biopsy – The removal of a tissue sample to see if cancer cells are present.

CBC (Complete Blood Count)
– A measure of the number of red blood cells, white blood cells, and platelets in the blood. Used to diagnose and monitor.

CT (Scan)
– A procedure that uses a computer linked to an x-ray machine to make a series of detailed pictures of areas inside the body. The pictures are taken from different angles and are used to create 3-dimensional (3-D) views of tissues and organs.

– Test to diagnose cancer by looking at a small number of cells under a microscope.

Diagnostic Profile
– Bloodwork to look at organ function (ex: looking at liver and kidney values).

Fine Needle Aspirate (FNA)
– The removal of small amounts of tissue or fluid with a thin needle for examination under a microscope for

Flow Cytometry
– A method of measuring the number of cells in a sample, the percentage of live cells in a sample, and certain characteristics of cells, such as size, shape, and the presence of tumor markers on the cell surface.

– In cancer, a description of a tumor based on how abnormal the cancer cells and tissue look under a microscope and how quickly the cancer cells are likely to grow and spread. Low-grade cancer cells look more like normal cells and tend to grow and spread more slowly than high-grade cancer cells. Grade of a tumor can often be used to predict how the tumor will behave.

– The study of diseased tissues using a microscope.

Metastatic Disease
– Cancer that has spread from the primary location to other parts of the body.

– The spread of cancer cells from the place where they first formed to another part of the body.

MRI (Magnetic Resonance Imaging)
– A procedure in which radio waves and a powerful magnet linked to a computer are used to create detailed pictures of areas inside the body. These pictures can show the difference between normal and diseased tissue. MRI makes better images of organs and soft tissue than other scanning techniques

– A positron emission tomography (PET) scan and a computed tomography (CT) scanning machine. A PET scan involves small doses of radio-labelled substances to determine how active the tumor is. The PET and CT scans are done at the same time with the same machine. The combined scans give more detailed pictures of areas inside the body than either scan gives by itself. A PET-CT scan may be used to help diagnose disease, plan treatment, or find out how well treatment is working.

PK (Pharmacokinetics) – Interactions of a drug and the body in terms of its absorption, distribution, metabolism, and excretion.

– An image produced on a sensitive plate or film by X-rays, gamma rays, or similar radiation, and typically used in medical examination.

Special Staining –
In some situations a definitive diagnosis may require using special techniques to identify the cause of the cancer.  These stains are applied to biopsy specimens after a pathologist has reviewed the general staining pattern of the tissue (see histopathology) to provide more detailed information.

– The extent of a cancer in the body. Staging is usually based on the size of the tumor, whether lymph nodes contain cancer, and whether the cancer has spread from the original site to other parts of the body.

– The process of finding out whether cancer has spread and if so, how far.

– A procedure that uses high-energy sound waves to look at tissues and organs inside the body. Ultrasound may be used to help diagnose cancer. Also called ultrasonography.


Chemotherapy – Chemotherapy is drug therapy designed to kill or slow the growth of cancers. Many of the drugs used are derived from natural substances such as plants, trees or even bacteria. Chemotherapy is frequently used to treat cancer that has spread to other parts of the body, to treat cancer that cannot be treated with surgery or radiation therapy alone or when it may enhance the effectiveness of these treatments.

– An abbreviation for a chemotherapy combination that is used to treat lymphoma. The CHOP protocol involves the use of several different drugs, cyclophosphamide, doxorubicin, vincristine and prednisone, given sequentially over 15 weeks.

– Debulking is a type of surgery, otherwise known as marginal resection, and involves incomplete removal of a tumor to enhance the efficacy of other treatment modalities such as chemotherapy, or radiation therapy.

– Intensity-modulated radiation therapy (IMRT) is a state-of-the-art cancer treatment method that delivers high doses of radiation directly to cancer cells in a very targeted way, much more precisely than is possible with conventional radiotherapy. IMRT involves varying (or modulating) the intensity of the radiation beam, so that the shape of the resulting dose distribution is tightly matched to the shape of the tumor.

Limb Spare
– A surgical alternative to treating patients with bone cancer. The aim of limb sparing is to save the leg instead of performing an amputation. The goal is to provide a functional, pain free leg.

Marginal Resection
– Otherwise known as debulking surgery, marginal resection is incomplete removal of a tumor to increase the effectiveness of other treatments such as chemotherapy, or radiation therapy.

– The edge or border of the tissue removed in cancer surgery. The margin is described as negative or clean when the pathologist finds no cancer cells at the edge of the tissue, suggesting that all of the cancer has been removed. The margin is described as positive or involved when the pathologist finds cancer cells at the edge of the tissue, suggesting that all of the cancer has not been removed.

– Low white blood count. In cancer treatment, chemotherapy may suppress the bone marrow and cause a drop in the white blood cell count, leading to increased risk of infection.

Palliative Care
– Care given to improve the quality of life and/or reduce pain, but not necessarily focused on long-term outcomes such as a cure or to lengthen the patient’s life.

– Stereotactic Radiation Therapy (SRT) is a type of external radiation therapy that uses special equipment to position the patient and precisely deliver high doses of radiation to a tumor.  It is also called stereotactic radiosurgery, gamma knife therapy and cyberknife therapy. SRT protocols are generally delivered in 1-5 fractions (doses) on consecutive or alternating days.

Patient Caregivers

Board Certified Veterinary Oncologist – A board-certified veterinary oncologist has completed extensive training after veterinary school that focuses in oncology (the way cancer develops and how to treat it). Most oncologists have completed three to five years of this focused training including an internship and a specialized residency on the subject of cancer. Throughout this training, an oncologist is required to pass comprehensive examinations and complete publication requirements to become board-certified.

  • Medical Oncologist – A veterinary oncologist who has special training in diagnosing and treating cancer using chemotherapy and other drug protocols. At the Flint Animal Cancer Center, our medical oncologists work with surgical and radiation oncologists to coordinate patient care.
  • Radiation Oncologist – A veterinary oncologist who has received advanced training in radiation oncology. The radiation oncologist specializes in the treatment of cancer patients using radiotherapy as the main modality of treatment.
  • Surgical Oncologist – A trained surgeon who has pursued advanced instruction in cancer surgery as well how to combine surgery with other cancer therapies such as chemotherapy and radiation therapy.

Faculty – Teaching staff of a college or university. At the Flint Animal Cancer Center, our clinical faculty supervise every patient case. All are doctors of veterinary medicine and are board-certified in their specialty (medical, surgical, and radiation oncology).

Fellow – An advanced trainee who has completed a D.V.M. program, internship, and residency, and seeks further specialized training. The Flint Animal Cancer Center supports the training of two surgical oncology fellows each year.

Intern (General and Specialty) General internships are one year clinical-intense programs that provide multidisciplinary training following completion of a D.V.M. program. Internship programs emphasize mentorship, direct supervision, and educational experiences including rounds, and formal presentations. Specialty internships, are also one-year, non-degree programs designed to prepare veterinarians for advanced specialty training such as an oncology residency.

Resident – An advanced trainee who has completed a D.V.M program as well as an internship and is pursuing highly specialized training in one of the cancer specialties.

Veterinary Technician – Veterinary technicians have been educated in the care and handling of animals, the basic principles of normal and abnormal life processes, and in many laboratory and clinical procedures. In general, veterinary technicians obtain 2-4 years of post-high school education and have an Associate’s or Bachelor’s degree in veterinary technology. They must pass a credentialing examination and keep up-to-date with continuing education to be considered licensed/registered/certified (the term used varies by state).