Dog Lymphoma Stages

If your dog has been diagnosed with lymphoma, it can feel like your whole world tilts. I have been there with families in the clinic who walked in for “just swollen glands” and walked out with a diagnosis that changed everything. The good news is that many forms of canine lymphoma, especially the common multicentric type, respond well to treatment. At the same time, lymphoma is not one single disease, so outcomes can vary by subtype, grade, and where it shows up in the body.

This guide walks you through what the stages mean, how vets determine them, and what you can do next.

What staging means (and what it does not)

Staging describes where the lymphoma is in the body and how far it has spread. Staging helps your veterinarian or veterinary oncologist:

• Choose the most appropriate treatment plan
• Estimate prognosis more accurately
• Create a baseline so you can track response to treatment

Three important clarifiers:

• Stage is not the same as grade. Grade describes how aggressive the cancer cells look under the microscope (how fast they tend to grow). Many cases of multicentric lymphoma in dogs are high-grade, but low-grade forms exist and often behave differently (slower course, different treatment goals).
• Stage does not perfectly predict how your dog will feel day to day. Some dogs with more advanced stage still act very normal at first.
• Lymphoma is not one disease. “Lymphoma” can mean different cell types (B-cell vs T-cell), different grades, and different anatomic forms (like multicentric vs gastrointestinal). Two dogs can share the same stage number and still need different discussions about treatment and expectations.

The 5 stages of canine lymphoma

Most veterinarians use the World Health Organization staging system for canine lymphoma.

Stage I

Cancer is found in one lymph node or one lymphoid tissue in a single location. This is less common because many dogs are diagnosed after multiple nodes enlarge.

Stage II

Multiple lymph nodes are involved, but they are generally in one region of the body (for example, several nodes in the neck).

Stage III

Generalized peripheral lymph node enlargement. In plain terms, lymph nodes in several areas are involved, like under the jaw, in front of the shoulders, and behind the knees.

Stage IV

Lymphoma has spread to the liver and/or spleen, often along with generalized lymph node involvement. Ultrasound and bloodwork can raise suspicion, but your vet may recommend an aspirate (sample) to confirm organ involvement when it will change the plan.

Stage V

Lymphoma has involved the bone marrow, and/or there are lymphoma cells in the blood (sometimes described as a leukemia phase), or it has spread to other organs such as the skin, lungs, eyes, or nervous system.

Substage a vs b

Along with stage, dogs are often categorized as:

• Substage a: your dog feels well, with little to no outward illness
• Substage b: your dog is showing systemic signs of illness

Examples of substage b signs include:

• Decreased appetite or weight loss
• Lethargy, less interest in walks or play
• Vomiting or diarrhea
• Increased thirst and urination
• Fever
• Labored breathing (especially with mediastinal involvement)

In many cases, substage b is associated with a more guarded prognosis, but it also gives your care team clear targets to improve comfort quickly.

Common lymphoma forms

Hearing “lymphoma” can make it sound like one straightforward diagnosis, but the presentation matters. A few common forms include:

• Multicentric: the classic “swollen lymph nodes” form (often under the jaw, in front of shoulders, behind knees). This is the most common and often responds well to chemotherapy.
• Gastrointestinal (alimentary): involves the intestines and can look like vomiting, diarrhea, weight loss, or poor appetite. Staging and treatment decisions can differ from multicentric cases.
• Mediastinal: involves lymph nodes in the chest and can cause coughing, breathing effort, or fluid buildup.
• Cutaneous: involves the skin and can appear as lumps, plaques, redness, or ulcers. Behavior can vary widely depending on the specific type.

Your veterinarian or oncologist can tell you which form they suspect based on exam findings, cytology or biopsy, and imaging.

How vets stage lymphoma

Not every dog needs every test on day one, and staging plans often change based on your dog’s symptoms, the suspected lymphoma type, and your budget. Here is the usual roadmap. Think of this as a “choose the right depth” menu you can discuss with your vet.

1) Confirming lymphoma

• Fine needle aspirate (FNA): a small needle sample from an enlarged lymph node. This is quick, minimally invasive, and often diagnostic.
• Biopsy: sometimes needed if results are unclear, if a specific lymphoma type is suspected, or if grade is important to confirm.

2) Baseline bloodwork

• CBC (complete blood count): checks red cells, white cells, platelets, and may suggest bone marrow involvement.
• Chemistry panel: evaluates organ function (liver, kidneys), electrolytes, and proteins.
• Urinalysis: helps interpret kidney values and overall health.

3) Imaging to look for spread

• Chest x-rays: checks for chest lymph node enlargement or fluid and evaluates the lungs.
• Abdominal ultrasound: evaluates spleen, liver, abdominal lymph nodes, and intestinal tract.

Imaging can strongly suggest organ involvement, but a sample (aspirate or biopsy) is sometimes needed for confirmation, especially if it will change the treatment plan.

4) Testing for type and behavior (optional but helpful)

• Immunophenotyping (B-cell vs T-cell): B-cell lymphoma often responds better to treatment than T-cell, on average.
• PARR testing: a DNA-based test that can help confirm lymphoma and determine clonality in tricky cases.

5) Bone marrow testing (sometimes)

A bone marrow aspirate is more likely if your dog has unexplained low blood cell counts, suspicious CBC results, or if your oncologist needs clarity for planning.

If you are overwhelmed by the list, you are not alone. A very reasonable question to ask your vet is: “Which tests will change what we do next?”

What staging can mean for treatment

Staging guides the plan, but it does not automatically dictate it. Many dogs with stage III to V still do very well with the right approach, especially if they feel well at diagnosis (substage a) and have a lymphoma type that tends to be chemo-responsive.

Common treatment paths

• Multi-agent chemotherapy (often CHOP-based protocols): the most common treatment with the best remission rates for many dogs.
• Single-agent chemo: sometimes chosen for cost, scheduling, or gentler intensity.
• Prednisone (steroid) alone: can temporarily shrink nodes and improve comfort, but it is usually not the best long-term control option.
• Radiation: sometimes used for localized disease or specific sites.
• Palliative care: focuses on comfort and quality of life when aggressive treatment is not the right fit for your family.

One important tip: If you are considering chemotherapy, talk to your vet before starting prednisone. Steroids can sometimes make lymphoma harder to treat later or shorten remission with certain chemotherapy plans. That said, vets also prescribe prednisone on purpose for urgent symptom relief, so the right answer depends on your dog’s situation.

Prognosis and remission

It is completely normal to want a number. Prognosis depends on the lymphoma form, stage and substage, grade, and whether it is B-cell or T-cell. Your oncologist is the best source for what applies to your dog.

• With CHOP-type chemotherapy: many dogs with multicentric lymphoma achieve remission. Typical first-remission times are often discussed in months, and some dogs do well longer.
• B-cell vs T-cell: B-cell lymphoma often has better average response and longer remission than T-cell, though individual dogs can surprise us in either direction.
• Substage b: if a dog is sick at diagnosis, the outlook is often more guarded, but symptom control can improve quality of life quickly.

If your vet gives you ranges, remember they are population averages, not a prediction for your dog as an individual.

At-home lymph node checks

Many lymphoma cases involve lymph nodes you can feel. Doing gentle checks at home helps you notice trends between appointments.

Where to feel

• Under the jaw (submandibular)
• In front of the shoulders (prescapular)
• In the armpits (axillary, sometimes harder to feel)
• Behind the knees (popliteal, often easiest)
• In the groin (inguinal)

How to do it

• Pick a calm moment, like after a walk or meal.
• Use the flats of your fingers, not poking.
• Feel both sides and compare symmetry.
• Do not worry about exact measurements. Focus on “same, smaller, bigger.”
• Do not palpate excessively. Repeated firm checking can make some dogs sore or stressed.
• Confirm what you are feeling. Not every lump is a lymph node, so ask your vet to show you which nodes to monitor on your dog.

If a node suddenly grows, becomes painful, or your dog seems unwell, call your vet. A fast change is meaningful information.

Questions to ask

Bringing a short list can help you feel more in control during emotional appointments.

• What stage and substage is my dog, and what findings led to that?
• What anatomic form of lymphoma do you suspect (multicentric, GI, mediastinal, cutaneous)?
• Do we know if this is B-cell or T-cell lymphoma?
• Do we know the grade (high-grade vs low-grade), and does it change our plan?
• Which treatment options fit my dog’s stage and overall health?
• What is a realistic goal: remission, time, comfort, or a mix?
• What side effects should I watch for at home, and when is it urgent?
• What is the monitoring plan (rechecks, bloodwork schedule, imaging)?
• What is the estimated cost range for each option?

Supportive care at home

Treatment is not just about medication. Daily support makes a big difference in how your dog feels.

Nutrition basics

• Keep food consistent during chemo weeks to avoid stomach upset from sudden changes.
• Prioritize highly palatable, digestible protein and adequate calories if appetite is reduced.
• Ask before adding supplements. Some supplements can interact with medications or affect the liver.

Hydration and gut support

• Encourage water intake with multiple bowls and fresh water changes.
• Discuss anti-nausea meds early if appetite dips. It is easier to prevent nausea than to chase it.
• Ask your vet if a probiotic is appropriate for your dog’s specific plan.

Chemo safety at home

If your dog is receiving chemotherapy, your team will give handling instructions. Common precautions include careful handling of urine and stool for a short window after treatment (often 48 to 72 hours, depending on the drug), wearing gloves if instructed, and washing hands after cleanup.

When to call your vet

Trust your instincts. Call the clinic or emergency vet if you see:

• Repeated vomiting or diarrhea, especially if your dog cannot keep water down
• Extreme lethargy or collapse
• Labored breathing or persistent coughing
• Bleeding, bruising, or very pale gums
• Fever (your vet can guide you on how to check safely)
• No interest in food for more than 24 hours (or sooner if your dog is fragile)

A gentle closing note

Lymphoma staging can sound clinical, but what it really offers is a plan. A plan means you can take the next step without guessing.

If you want, write down your dog’s stage, substage, current appetite, and energy level before your next appointment. Those details help your vet tailor care to your dog as a whole living being, not just a diagnosis.