If your dog has just been diagnosed with lymphoma, take a deep breath; you’re not alone. Lymphoma is one of the most common cancers in dogs, making up about 15–20% of all canine cancer cases (Vail & Thamm, 2020).
While that statistic can sound overwhelming, here’s something hopeful: lymphoma is also one of the most treatable cancers in dogs, and many dogs respond beautifully to chemotherapy, reaching remission and enjoying months, sometimes years, of excellent quality of life (Vail & Thamm, 2020; Vail, 2013).
What Exactly Is Lymphoma?
Lymphoma (also called lymphosarcoma or LSA) is a cancer of lymphocytes, the white blood cells that act like your dog’s personal security guards identifying threats, sounding the alarm, coordinating defenses, and remembering past invaders. In lymphoma, those cells go rogue and multiply uncontrollably, crowding out healthy cells (Vail & Thamm, 2020).
Because lymphocytes are found throughout the body, lymphoma can appear in lymph nodes, spleen, liver, bone marrow, the digestive tract, skin, and other tissues (Withrow et al., 2020).
Different Types of Lymphoma in Dogs
The most common form, multicentric lymphoma, accounts for around 80–85% of cases and typically shows up as swollen but painless lymph nodes, often under the jaw, in front of the shoulders, or behind the knees (Withrow et al., 2020).
Other forms include alimentary (gastrointestinal) lymphoma with vomiting or diarrhea and weight loss, mediastinal lymphoma in the chest causing coughing or breathing issues, extranodal lymphoma in organs like the kidneys or skin, and cutaneous (skin) lymphoma with red, scaly, or nodular lesions (Rassnick, 2015; Zandvliet, 2016).
B-Cell vs. T-Cell: Why It Matters
Veterinary oncologists often describe lymphoma by which type of lymphocyte is affected. B-cell lymphoma tends to respond better to chemotherapy, with typical survival times around 12–24 months with multi-drug protocols (Vail & Thamm, 2020; Garrett et al., 2002).
T-cell lymphoma is often more aggressive, with shorter average survivals of about 7–8 months and may be associated with high calcium levels (Zandvliet, 2016). Certain breeds, like Boxers and Golden Retrievers, are more likely to develop T-cell lymphoma (Modiano et al., 2005).
Your oncologist may recommend flow cytometry or biopsy testing to determine whether the lymphoma is B-cell or T-cell, as these details guide both prognosis and treatment (Vail & Thamm, 2020).
“Why Did This Happen?”
Most cases of lymphoma result from a combination of genetics, environment, and immune factors, not anything you did wrong.
Certain breeds (Boxers, Golden Retrievers, Bernese Mountain Dogs, Saint Bernards, and Basset Hounds) carry higher inherited risk (Modiano et al., 2005; Pastor et al., 2009).
Environmental exposures, including some lawn chemicals and household cleaning products, have been linked to higher lymphoma risk (Gavazza et al., 2001; Takashima-Uebelhoer et al., 2012).
Unlike cats, where a virus (FeLV) can directly cause lymphoma, no single infectious cause has been confirmed in dogs, though viral activity has been detected in some samples (Tomley et al., 1983).
Common Signs to Watch For
The hallmark sign of lymphoma is painless, enlarged lymph nodes that feel firm but movable. Many dogs otherwise act completely normal at first (Vail & Thamm, 2020).
As the disease progresses, you may notice decreased appetite, weight loss, lethargy, increased thirst or urination, vomiting, diarrhea, coughing, or changes in the skin (Zandvliet, 2016; Withrow et al., 2020).
How Lymphoma Is Diagnosed
Diagnosis usually starts with a fine needle aspirate (FNA) of a lymph node — quick, minimally invasive, and often diagnostic. To refine prognosis and plan therapy, vets may add flow cytometry (to determine B- or T-cell origin) or a biopsy with histopathology for detailed tissue evaluation (Vail & Thamm, 2020).
Additional tests such as bloodwork, X-rays, ultrasound, or bone marrow aspirate may be used to stage the disease (Withrow et al., 2020).
Treatment Options and What to Expect
For most dogs, chemotherapy is the gold standard. Unlike humans, dogs tolerate chemotherapy extremely well. Most experience mild or no side effects, and their quality of life is prioritized throughout (Vail, 2013).
The most common treatment plan, called CHOP, uses four drugs over several months. It achieves remission in 80–90% of dogs with B-cell lymphoma, with median survival of 12–14 months (Garrett et al., 2002).
Other treatment paths include single-agent chemotherapy (less expensive but lower remission rates), prednisone alone for short-term comfort, and palliative care focusing solely on quality of life (Zandvliet, 2016).
Prognosis: What Affects Outcomes
Better prognostic signs include B-cell type, lower disease stage, no clinical symptoms at diagnosis, normal calcium, and strong early response to chemotherapy (Vail & Thamm, 2020; Zandvliet, 2016).
T-cell type, high stage, hypercalcemia, and failure to achieve remission are associated with shorter survival (Zandvliet, 2016). Without treatment, median survival is typically four to six weeks, though prednisone alone may provide one to three months of comfort (Vail & Thamm, 2020).
Research and Hope Ahead
Ongoing research continues to bring new hope for dogs with lymphoma. The Golden Retriever Lifetime Study, funded by the Morris Animal Foundation, is helping scientists uncover genetic and environmental factors that influence lymphoma development (Marconato et al., 2011).
New diagnostic tools, such as early detection and minimal residual disease monitoring, aim to help veterinarians tailor treatments to each dog’s unique case (Vail & Thamm, 2020).
You’re Not Alone
A lymphoma diagnosis can feel overwhelming, but thousands of families face this journey every year — and many dogs live long, happy lives during and after treatment. Whether you choose full chemotherapy, a modified approach, or palliative care, your love and commitment mean the world to your dog.
The bottom line: lymphoma is serious but often very treatable, and many dogs maintain excellent quality of life during therapy and remission (Vail, 2013; Garrett et al., 2002).
References
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Gavazza, A., Presciuttini, S., Barale, R., Lubas, G., & Gugliucci, B. (2001). Association between canine malignant lymphoma, living in industrial areas, and use of chemicals by dog owners. Journal of Veterinary Internal Medicine, 15(3), 190–195. https://doi.org/10.1111/j.1939-1676.2001.tb02310.x
Marconato, L., Gelain, M. E., & Comazzi, S. (2011). The dog as a possible animal model for human non-Hodgkin lymphoma: A review. Hematological Oncology, 31(1), 1–9. https://doi.org/10.1002/hon.2017
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Pastor, M., Chalvet-Monfray, K., Marchal, T., Keck, G., Magnol, J. P., Fournel-Fleury, C., & Ponce, F. (2009). Genetic and environmental risk indicators in canine non-Hodgkin's lymphomas: Breed associations and geographic distribution of 608 cases diagnosed throughout France over one year. Journal of Veterinary Internal Medicine, 23(2), 301–310. https://doi.org/10.1111/j.1939-1676.2008.0255.x
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Takashima-Uebelhoer, B. B., Barber, L. G., Zagarins, S. E., Procter-Gray, E., Gollenberg, A. L., Moore, A. S., & Bertone-Johnson, E. R. (2012). Household chemical exposures and the risk of canine malignant lymphoma, a model for human non-Hodgkin’s lymphoma. Environmental Research, 112, 171–176. https://doi.org/10.1016/j.envres.2011.12.003
Tomley, F. M., Armstrong, S. J., Mahy, B. W., & Owen, L. N. (1983). Reverse transcriptase activity and particles of retroviral density in cultured canine lymphosarcoma supernatants. British Journal of Cancer, 47(2), 277–284. https://doi.org/10.1038/bjc.1983.39
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Vail, D. M., & Thamm, D. H. (2020). Hematopoietic tumors. In S. J. Withrow, D. M. Vail, R. L. Page, & E. G. MacEwen (Eds.), Withrow and MacEwen's small animal clinical oncology (6th ed., pp. 688–772). Elsevier.
Withrow, S. J., Vail, D. M., Page, R. L., & MacEwen, E. G. (Eds.). (2020). Withrow and MacEwen’s small animal clinical oncology (6th ed.). Elsevier.
Zandvliet, M. (2016). Canine lymphoma: A review. Veterinary Quarterly, 36(2), 76–104. https://doi.org/10.1080/01652176.2016.1152633