Lymphoma in dogs — stages, treatment choices, and the decision points

The short answer

Most owners arrive at lymphoma after finding firm, painless, symmetric lymph-node enlargement under the jaw, in front of the shoulders, or behind the knees. The dog often looks well at the time of diagnosis. That apparent wellness is part of why the decision is hard: the data on the page argues for treatment that the dog in front of you doesn’t obviously need.

How it presents

Multicentric lymphoma — about 80% of canine lymphomas — typically shows up as multiple enlarged lymph nodes, painless and rubbery to palpate. Owners notice them while petting or grooming. The dog usually feels well; appetite and energy can be normal.

Other patterns include alimentary (gastrointestinal — chronic vomiting, diarrhoea, weight loss), mediastinal (chest mass causing breathing changes, fluid build-up), cutaneous (skin nodules, often confused with infection), and extranodal forms in the eye, central nervous system, or specific organs. Each behaves differently and is treated differently.

B-cell vs T-cell vs others

The distinction matters because outcomes differ substantially. Roughly 70% of canine lymphoma is B-cell; 30% is T-cell. B-cell is more responsive to standard chemotherapy and produces longer remissions. T-cell — particularly the high-grade variants — runs faster, shorter, and harder. Immunophenotyping (a flow-cytometry or PARR test) tells you which you are dealing with, and is worth doing before committing to a treatment path.

A small subset is indolent or low-grade lymphoma — small lymphocytic lymphoma, T-zone lymphoma, marginal-zone — which can be managed for years on chlorambucil and prednisolone, similar to early-stage chronic lymphocytic leukaemia in humans. These dogs sometimes live close to normal lifespans.

Staging — what your vet checks

The WHO clinical stages for canine lymphoma run I to V. Stage I is a single node; stage V is bone marrow or extranodal organ involvement. Stage III (multiple nodes both sides) is the most common presentation. Substage "a" means the dog feels well; substage "b" means there are clinical signs (lethargy, anorexia, fever).

A standard work-up before treatment includes:

• Fine-needle aspirate or excisional biopsy to confirm diagnosis.
• Immunophenotyping (flow cytometry or PARR) to determine B-cell vs T-cell.
• CBC, biochemistry, urinalysis — baseline for treatment safety.
• Chest radiographs and abdominal ultrasound to look for organ involvement.
• Bone marrow aspirate — only sometimes, depending on suspicion of stage V.

Treatment options

Three realistic paths. Each is defensible.

1. CHOP-based chemotherapy. The standard combination protocol — cyclophosphamide, doxorubicin, vincristine, prednisone — given as weekly visits over 16–25 weeks. Median survival 8–12 months for B-cell, with around 70% achieving remission. Cost in India: ₹1.5–3 lakh; in the UK/US: £4–10k / $4–10k. Side effects: typically mild GI upset; 5–10% have serious complications.
2. Prednisolone-only palliation. Steroid alone produces a 4–6 week median remission. Cheap, oral, no clinic visits beyond bloodwork. The catch: once prednisolone is given, the dog can no longer enter most chemotherapy trials and CHOP outcomes are reduced if started later. Choose this only if you are sure you do not want to attempt cure-orientation.
3. Single-agent chemotherapy (doxorubicin solo, or COP). Middle path. Median survival 4–7 months. Less commitment than CHOP, more efficacy than prednisolone alone. Useful when CHOP is unaffordable or the dog cannot tolerate weekly visits.

Newer options — monoclonal antibodies (rabacfosadine), tyrosine-kinase inhibitors, immunotherapy combinations — have a place in specific contexts and are worth asking about if you are at a referral hospital.

How to decide

Five questions that help most owners reach a defensible decision:

1. How old is my dog, and what is normal life expectancy from here? A 12-year-old large-breed dog has perhaps 1–2 years of normal life ahead; chemotherapy buys months at the cost of those months being clinic-heavy. A 6-year-old has a different calculation.
2. How much of the time on treatment will be good time? The Lap of Love QoL scale or HHHHHMM, applied weekly, will tell you whether the chemotherapy is buying time the dog enjoys.
3. What is the cost — financial and attentional — and can I sustain it without resentment? Resentment of treatment toward the end is a reliable amplifier of grief.
4. Will my dog tolerate the protocol? Some dogs find weekly clinic visits intolerable; others adapt. The first 1–2 visits tell you which kind you have.
5. What would my vet do for their own dog? Ask. A vet who has done this work for 10+ years has a defensible intuition; the answer is informative.

When to consider stopping

Sometimes treatment is working in the data and not working for the dog. Watch for these signs that the off-ramp may be the right call:

• Two or more treatment-related hospital admissions in a month.
• Persistent appetite loss between cycles, despite appetite stimulants.
• The dog hides on clinic-visit mornings — repeatedly, not once.
• HHHHHMM score below 35, sustained for two weeks.
• Owner financial or emotional sustainability is tipping into harm.

Stopping treatment is not giving up. It is the recognition that the work has changed from extending life to making the remaining life as comfortable as possible. The transition is itself a treatment decision, and a defensible one.

Editorial reference, not veterinary advice. — Dr. NRS, last reviewed 28 April 2026.