Lymphoma in Dogs: Signs, Diagnosis, Treatment Options and What to Expect

Call your vet and arrange an exam. Do not try to work out the cause by feeling the lump, because the Merck Veterinary Manual notes that lymphoma is not confirmed by how a lump looks or where it sits. Infection, inflammation, immune disease, dental disease and other cancers can all enlarge lymph nodes, and only a sample can sort them out.

See a vet soon for any new firm or lasting swollen node, several enlarged nodes, unexplained weight loss, a smaller appetite, tiredness, fever, vomiting, diarrhea, more thirst or urination than usual, skin sores, or any unexplained mass.

Go the same day, or call an emergency vet, for any of these:

• Trouble breathing.
• Collapse.
• Severe weakness.
• A dog who has stopped eating.
• Repeated vomiting with weakness or dehydration.
• Severe belly pain, or fast-worsening swelling at the throat or neck.
• Pale gums or severe distress.

AAHA's 2026 oncology guidelines give one example of how urgent this can get: enlarged lymph nodes under the jaw that block the upper airway call for an immediate referral to an oncologist. If you need a clinic fast, the DogServ directory lists vets and emergency vets.

Lymph nodes are small immune-system structures that filter lymph fluid and help immune cells respond to anything foreign. They swell with infection, inflammation, cancer cells or other medical causes. You can usually feel the ones under the jaw, in front of the shoulders and behind the knees.

In the common multicentric form, Merck's owner material describes firm, enlarged, usually painless nodes, often in several of those spots at once. Some dogs also get tired, lose weight, eat less, run a fever, or become weak or dehydrated. Dogs with slow-growing, low-grade lymphoma may show few outward signs, so a dog who looks fine can still have a node worth testing.

Other signs depend on where the cancer sits. Disease in the belly can bring vomiting, diarrhea and belly pain. Disease in the chest can cause breathing trouble, and some dogs drink and urinate more because of high blood calcium. Skin lymphoma can look like sores, scaling or hair loss, but skin changes alone can't confirm it. Lymphoma is a cancer of the dog's own immune cells, not a contagious infection. If you want a baseline for what normal looks like, start with signs of a healthy dog.

Vets sort lymphoma by where it starts, and the form shapes both the signs and the plan. Merck and AAHA describe these:

• Multicentric lymphoma affects several lymph-node groups and is the most common form, roughly 80% to 85% of canine cases in Merck's owner material.
• Alimentary lymphoma affects the digestive tract, under 10% of cases in Merck's owner material. If your dog has vomiting or diarrhea, see dog vomiting and dog diarrhea for when to call the vet.
• Mediastinal lymphoma affects lymph nodes or the thymus in the chest. It can cause breathing difficulty or fluid around the lungs.
• Cutaneous lymphoma affects the skin, and other extranodal forms can involve organs such as the kidneys, eyes or bones.

Your vet may also talk about cell type and grade. B-cell and T-cell describe the immune-cell lineage and can affect how a dog responds to treatment. High-grade lymphoma generally progresses faster; low-grade forms can move slowly.

Diagnosis usually starts with a physical exam, then often a fine-needle aspirate. The vet collects cells from an enlarged node or affected organ with a thin needle, and a pathologist examines them. VCA Animal Hospitals and AAHA both describe this as a common first test, and it often identifies lymphoma.

Some dogs need more. A biopsy gives a closer look at tissue when the needle sample is inconclusive, the spot is hard to sample, or the vet needs more on grade. Flow cytometry analyzes cell markers and can help tell B-cell from T-cell. Immunohistochemistry uses tissue stains to identify cell type. PARR is a molecular test that can support a lymphoma diagnosis in selected cases. Bloodwork, including a blood count, chemistry panel, urinalysis and calcium, shows how the rest of the body is doing.

Staging means working out how far the disease has spread. It can include chest X-rays, belly ultrasound, CT, or sampling of a node or organ. AAHA says staging should be purposeful, because some tests will not change the treatment or the outlook, while cell typing can be useful. It is fair to ask your vet which tests will change the plan. Prices vary by practice and region, so ask the clinic for an itemized estimate that covers the exam, sampling, lab reading, cell typing, bloodwork, imaging, sedation and follow-ups.

The right plan depends on the form, grade, stage, cell type, how your dog feels, your goals, your time and cost. I do not give doses here; your vet or oncologist sets the drugs, amounts and schedule. Veterinary sources describe these options by class:

• Multi-agent chemotherapy. CHOP-based protocols combine drug classes represented by cyclophosphamide, doxorubicin, vincristine and prednisone or prednisolone. This is the usual approach for multicentric lymphoma, which is generally systemic.
• Single-agent and rescue chemotherapy. Doxorubicin alone, lomustine, mitoxantrone, rabacfosadine, verdinexor or rescue protocols may be used in selected cases.
• Prednisone alone. It may improve signs and comfort for a while, but it is palliative, not a cure, and it can affect later chemotherapy options. Ask your vet about timing before starting it.
• Radiation and surgery. Either may be used for selected localized disease, chest complications or comfort, but surgery is not the usual treatment.
• No active cancer treatment. Comfort-focused care is a real choice when treatment is not possible, not wanted, or unlikely to give acceptable quality of life.

Many owners expect chemotherapy to make a dog as sick as it makes a person. VCA says dogs rarely lose their hair or seem ill during treatment, and AAHA says veterinary chemotherapy is built around quality of life and is generally well tolerated. AAHA reports that about 15% to 30% of dogs on chemotherapy have side effects, usually mild and manageable, with a small minority having serious complications. Possible effects include vomiting, diarrhea, less appetite, tiredness, a drop in infection-fighting white blood cells, and occasionally a hospital stay. Ask your oncology team which signs mean you should call right away.

I wish I could give you one number for your dog, but outcomes vary a lot with the form, stage, cell type and response. In groups of dogs, studies report these outcomes.

A 2017 study from Hofheim and Giessen followed 408 dogs on a CHOP-L-asparaginase-based protocol. In dogs who stopped after the first phase, median overall survival was 304 days. In dogs who continued with maintenance, it was 375 days. One-year survival was 39% and 50%, and the study found no statistically significant difference in overall survival between the two approaches.

A 2022 study by Bettini and colleagues treated 144 dogs with a 12-week CHOP-based protocol followed by lomustine. Complete remission happened in 104 dogs, or 72.2%. Median overall survival was 291 days across all dogs, 357 days for B-cell lymphoma and 210 days for T-cell lymphoma.

For dogs who get no treatment or prednisone only, VCA and Merck describe survival of roughly four to six weeks, while treated multicentric lymphoma commonly has a median survival around a year.

Remission means the signs or detectable disease have shrunk back. It does not mean cure. Relapse is expected in most aggressive cases, although some low-grade forms stay controlled for longer. These are group medians, so some dogs did better and some worse. Your vet can tell you what to expect for your dog.

North Carolina State University's veterinary hospital publishes dated estimates for multicentric lymphoma, accessed September 2026. Its table lists:

• CHOP protocol: $600 to $800 per treatment, about $6,000 to $8,000 for the whole protocol.
• Doxorubicin alone: $600 to $800 per treatment.
• Rabacfosadine alternating with doxorubicin: about $4,200 to $6,400 for the protocol.
• Verdinexor: about $300 to $500 per month, depending on body weight.
• Prednisone alone: about $20 to $30 per month.

Those are one hospital's estimates, and they leave out supportive care and hospitalization. They are not a national price. Ask every clinic what its estimate includes: anti-nausea medication, bloodwork, rechecks, emergency visits, and treatment if the lymphoma comes back. Travel and time off work add up too. If you have a policy, read pet insurance for dogs for coverage questions, exclusions and waiting periods before you count on it.

AAHA says the goal of symptom care is to keep or improve your dog's quality of life by easing discomfort and relieving signs, and that the choices should reflect your goals, your limits and your dog's condition. Keep a simple daily record of:

• Appetite, and whether food stays down.
• Hydration and breathing comfort.
• Pain or restlessness.
• Mobility and sleep.
• Interest in you and normal activities.
• Good days versus bad days.
• Side effects, and how your dog recovers between treatments.
• Whether the care load is manageable for your household.

Your vet can treat nausea, vomiting, diarrhea, appetite loss, pain and dehydration as part of comfort care, and the medicines and feeding plan have to come from the veterinary team. Do not start a special cancer diet on your own, since no food is shown to treat lymphoma.

AAHA recommends reassessing regularly and says goals can change as the disease, the response to treatment, or your priorities change. The AVMA says euthanasia may need to be considered when treatment is unlikely to succeed, when its demands or cost are more than a family can provide, or when quality of life stays poor despite treatment. This is a hard conversation, and starting it does not mean you are giving up. A question that can open it: what does my dog enjoy now, what signs can be relieved, what burden will treatment add, and what change would tell us the plan no longer serves my dog? For older dogs, senior dog care covers comfort and daily monitoring.

Bring a written list. The AVMA encourages owners to ask questions, consider a referral to a veterinary oncologist, and ask about clinical trials. Good questions include:

• What exact type, grade, cell type and stage does my dog have?
• What is the goal: remission, control or comfort?
• How many visits will there be, and what happens at each?
• What does the estimate include, and what does it leave out?
• Are hospitalization, anti-nausea medication, emergency care and relapse treatment covered in it?
• Which side effects mean I should call right away?
• What is the plan if the first protocol does not work?
• What is the comfort-care alternative?
• Are clinical trials available?

These are the questions that come up most.

It depends on the type, stage, cell type and response. In the 2022 study of 144 dogs, median overall survival was 291 days, with 357 days for B-cell and 210 days for T-cell lymphoma. Those are group results, and your vet can speak to your own dog.

Firm, painless lumps under the jaw, in front of the shoulders or behind the knees are the most common. Tiredness, weight loss, less appetite and fever can come with them.

There is no single checklist, and it differs from dog to dog. Watch appetite, breathing, pain, mobility, sleep and the balance of good days and bad days, and talk with your vet about comfort care as those slip. Trouble breathing, collapse or refusing food calls for same-day care, and your vet can also talk with you about when euthanasia should be considered.

Yes. Lymphoma in the chest can cause breathing difficulty or fluid around the lungs, and swollen nodes at the throat can block the upper airway. Hard, labored breathing is a same-day emergency, so go to an emergency vet.

Call your vet today if you have felt a lump, and go straight in if your dog's breathing, strength or appetite has changed. If lymphoma is confirmed, ask for an itemized estimate, a clear statement of the treatment goal, and a referral to a veterinary oncologist if you want a specialist's view. The DogServ directory can help you find vets and emergency vets near you. However you decide, choose the plan that fits your dog's comfort and what your family can carry.

• American Animal Hospital Association: AAHA's 2026 oncology guidelines
• American Animal Hospital Association: AAHA
• American Animal Hospital Association: AAHA
• American Veterinary Medical Association: AVMA
• hospital.cvm.ncsu.edu: Its table
• Merck Veterinary Manual: Merck's owner material
• Merck Veterinary Manual: the Merck Veterinary Manual
• PubMed: 2017 study from Hofheim and Giessen
• PubMed Central: 2022 study by Bettini and colleagues
• VCA Animal Hospitals: VCA Animal Hospitals