Skip to main content
MD
MedicalDictionary.comThe Free Veterinary Medical Dictionary
Medical Condition🐕 Dogs🐈 Catshematologic immune

Lymphoma (Lymphosarcoma)

🗣️ Pronounced:lim-FOH-muh / lim-foh-sar-KOH-muh
In One Sentence (Plain English)

A malignant cancer arising from lymphocytes, a type of white blood cell vital to the immune system.

Editorial Status: Verified from peer-reviewed veterinary sources (v1.0)
Updated: 2026-01-15

💬 In Plain English

Lymphocytes circulate throughout the bloodstream, lymph nodes, spleen, and bone marrow. When these cells undergo malignant changes, they divide uncontrollably. In dogs, the most common form is multicentric lymphoma, where owners discover firm, painless, rubbery swellings under the jaw, in front of the shoulders, or behind the knees. In cats, lymphoma most often attacks the gastrointestinal tract, causing weight loss, vomiting, and diarrhea.

🔬 Clinical & Technical Depth

For Vets & Technicians

Formal Clinical Definition

Clonal neoplastic proliferation of lymphoid cells classified anatomically (multicentric, alimentary, mediastinal, cutaneous) and immunophenotypically (B-cell vs. T-cell) according to the WHO classification system.

Why Veterinarians Use It

Veterinarians diagnose lymphoma through cytology or biopsy to differentiate neoplastic lymphadenopathy from infectious or reactive lymph node inflammation.

Clinical Context Encountered

Encountered during wellness exams when swollen lymph nodes are palpated, or during investigations into feline chronic vomiting, weight loss, or canine hypercalcemia.

Clinical Reference Guide (Medical Condition)

Severity
Emergency StatusNon-Emergency Care
🚨 Red Flag Warnings (When to Contact an Emergency Vet)
  • •Hypercalcemia of malignancy (elevated blood calcium produced by some lymphomas) causes severe polydipsia, lethargy, and kidney failure requiring prompt intervention.

❓ Questions to Ask Your Veterinarian

Take these actionable questions with you to your next clinic visit or appointment:

  • 1What anatomical form of lymphoma does my pet have (multicentric, gastrointestinal, mediastinal)?
  • 2What is the immunophenotype (B-cell or T-cell) based on flow cytometry or PARR testing?
  • 3What are the differences between multi-agent chemotherapy (CHOP protocol) versus single-agent protocols or palliative prednisone alone?
  • 4What is the expected remission rate and survival timeline for my pet’s specific subtype?

Academic & Clinical References