Home » Pet Health » Cancer 101 » How is Cancer Diagnosed and Treated?


The key to detecting cancer at an early stage is to monitor your pet regularly, especially as they age. The detection and diagnosis of cancer at an initial stage can significantly improve cancer outcomes. In every kind of animal in which cancer grows, growth starts with one genetic change in a normal cell, converting the cell to a cancerous type, giving it the power to grow abnormally and spread inside the body. If we can detect cancer when it is just starting to grow as a tiny nodule, we can apply treatment much earlier, control cancer growth, and prolong the life of our beloved companions.

To ensure early detection:

    1. Schedule annual appointments with your vet.
    1. Try to be conscious of every lump or rash on your furry friend’s body when you pet them. If you notice anything irregular (physically, emotionally, or behaviorally), take them to your vet.
    1. Early detection is more than the key to a better outcome and greater life expectancy; it is the key to cancer prevention and a pathway to your overall peace of mind.

If your vet does suspect that your pet has cancer, they begin the diagnosis by investigating physical signs including the presence of a lump, loss of appetite, lack of energy, and weight loss. The next step is a clinical examination. Your vet may use various lab tests, including blood and urine tests and tissue biopsy (taking a tissue sample using a fine needle). They may also perform imaging tests such as X-ray, ultrasound, magnetic resonance imaging (MRI), computerized tomography (CT), and positron emission tomography (PET).


Treatment of cancer varies greatly depending on the type, location, and grade of cancer, as well as your pet’s general health. Chemotherapy, radiation, or surgical removal are the commonly used treatment options. The response to the treatment depends on the type and extent of the cancer. Benign tumors are usually easier to treat, no matter when detected. They may even be left alone, whereas treatment of malignant tumors is more likely to be successful if caught early. While some types of aggressive cancers are challenging to cure, treatment can still profoundly affect your pet’s quality of life.

Many cancer treatment options are available, as listed below:

    • Surgery – removes as much cancer as possible.
    • Chemotherapy – uses drugs to kill cancer cells.
    • Radiation therapy – uses high-powered energy beams, such as X-rays or protons, to kill cancer cells.
    • Bone marrow transplant –  bone marrow is the material inside your pet’s bones that makes blood cells from blood stem cells; a bone marrow transplant, also known as a stem cell transplant, can use your pet’s bone marrow stem cells or those from a donor pet to replace cancer cells with new, normal cells (used in canine lymphoma)
    • Immunotherapy – also known as biological therapy; uses the body’s immune system to recognize cancer as foreign and fight it.
    • Targeted drug therapy – focuses on specific abnormalities within cancer cells that allow them to survive and uses drugs to disable those features.
    • Cryoablation – a treatment that kills cancer cells with cold temperatures using a thin, wand-like needle through your pet’s skin to enter the cancerous tumor directly; a gas is pumped into the cryoprobe to freeze the tissue, then thaw, repeating the procedure several times during the same treatment session to kill the cancer cells

A cancer diagnosis can be scary, and learning to ensure early detection and appreciating what treatment options are available for your pet might ease some of that fear. Understanding how to manage the disease allows you to talk to your vet with confidence about the benefits and risks of each cancer treatment. With the help of your vet team, you can find a treatment that best suits your pet’s diagnosis so you can look forward to many happy years with your pet.

The Pet Cancer Foundation’s Website Editorial team is comprised of veterinarians, veterinary oncologists, and veterinary technicians, as well as scientific writers and editors who have attained their PhD’s in the life sciences, along with general editors and research assistants. All content found in this section goes through an extensive process with multiple review stages, to ensure this extended resource provides pet families with the most up-to-date information publicly available.

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Keep Your Pets Healthy Editorial Team

Last Updated: October 14, 2022

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The following sources were referenced to write the content on this page: 

Beltrán Hernández, I, Kromhout, JZ, Teske, E, Hennink, WE, van Nimwegen, SA & Oliveira S 2021, ‘Molecular targets for anticancer therapies in companion animals and humans: what can we learn from each other?’, Theranostics, vol. 11, no. 8, pp. 3882-3897.

Biller, B, Berg, J, Garrett, L, Ruslander, D, Wearing, R, Abbott, B, Patel, M, Smith, D & Bryan C 2016, ‘AAHA Oncology guidelines for dogs and cats’, J Am Anim Hosp Assoc vol. 52, no. 4, pp. 181-204.

Londhe, P, Gutwillig, M & London C 2019, ‘Targeted therapies in veterinary oncology’, Vet Clin North Am Small Anim Pract, vol. 49. no. 5, pp. 917-931.

Schleis, SE 2014, ‘Cancer screening tests for small animals’, Vet Clin North Am Small Anim Pract, vol. 44, no. 5, pp. 871-881.

Thamm, DH 2019, ‘Canine cancer: strategies in experimental therapeutics’, Front Oncol, vol. 9, no. 1257, pp. 1-9.

National Cancer Institute, How Cancer Is Diagnosed (Updated, July 17, 2019), viewed Oct. 3, 2022, https://www.cancer.gov/about-cancer/diagnosis-staging/diagnosis

Mayo Clinic, Cancer treatment, viewed October 3, 2022, https://www.mayoclinic.org/tests-procedures/cancer-treatment/about/pac-20393344

The Pet Cancer Foundation’s medical resource for pet owners is protected by copyright.

For reprint requests, please see our Content Usage Policy.