Lymphoma in Dogs: Stages and When to Say Goodbye

If your dog has just been diagnosed with lymphoma, or a vet suspects it, here’s what lymphoma in dogs usually looks like. It often shows up in a dog who seems well, with a firm lump someone notices under the neck or behind a knee, and a needle sample usually confirms it.

Lymphoma is one of the most common cancers in dogs, and it starts in the immune system. It’s rarely cured. Vets stage it from I to V by how far it has spread, and families choose among chemotherapy, prednisone, comfort care, and euthanasia, sometimes more than one along the way.

Families decide when to say goodbye in different ways: at diagnosis, over one change like breathing, or by watching their dog’s days with a vet. Below are the first signs, the stages, each treatment path with its cost, how long dogs tend to live on each, what the end stage can look like, and whether a dog with lymphoma will die naturally. This guide doesn’t replace a vet who can examine your dog. If your dog has already died, we’re so sorry.

Key Takeaways

• Lymphoma is a cancer of lymphocytes, a kind of white blood cell. People often first notice firm, painless swelling of the lymph nodes under the neck, in front of the shoulders, or behind the knees.
• Vets stage lymphoma from I to V by how far it has spread, and add substage a (not sick) or b (sick). T-cell lymphoma, stage V, and substage b are linked with a harder outlook, and a dog can start treatment without every staging test.
• Paths include treatment (multi-drug chemo such as CHOP, a single drug, or prednisone), comfort care, and euthanasia, and comfort care can go alongside treatment. A plan can change over time.
• A dog’s lifespan with lymphoma depends on the type, stage, and treatment, and published figures describe groups of dogs rather than any one dog. Families decide when to say goodbye in different ways, often by looking at eating, breathing, comfort, and how their dog responds to them, with a vet’s help.
• A dog can die of lymphoma without euthanasia. If there’s time, a vet can help you plan a natural death with comfort care, including whether to use sedation, just as they can help you plan euthanasia.

What Is Lymphoma in Dogs?

Lymphoma in dogs starts when lymphocytes, the immune cells that normally fight infection, begin multiplying out of control. Those cells travel through the lymph nodes, spleen, liver, and bone marrow, so lymphoma usually behaves as a whole-body disease rather than a single lump.

When a lymphocyte becomes cancerous, it divides out of control and produces large numbers of identical cells, crowding the lymph nodes and making them swell. That’s why swollen nodes are so often the first sign.

Lymphoma isn’t rare. The AKC Canine Health Foundation estimates that approximately 1 of every 15 dogs born today will get lymphoma at some point in their life, most often between 8 and 11 years old. Boxers, Rottweilers, and Golden Retrievers may be at higher risk, but any breed can be affected. Mixed-breed dogs get lymphoma too.

Merck notes that the causes and origin of the disease are not well understood. Nobody fully knows why it starts.

Types of Lymphoma in Dogs

Vets sort lymphoma by where it shows up in the body, because the location shapes the signs and the outlook:

• Multicentric lymphoma starts in the lymph nodes. It’s by far the most common form, accounting for about 80%-85% of cases, and it’s the form most of this guide describes.
• Alimentary lymphoma, the second-most common type, affects the stomach and intestines. It tends to look like other gut problems, with vomiting, diarrhea, and weight loss.
• Mediastinal lymphoma occurs in the chest, in the lymph nodes or thymus, and can cause coughing or breathing trouble.
• Extranodal lymphoma starts outside the lymph system, most often in the skin, and less often in the eyes, kidneys, lungs, or nervous system.

There’s also a slower kind. Merck notes that a low-grade form occurs up to 30% of the time. Low-grade, or indolent, lymphoma grows slowly, and some dogs with it show no signs for a long while.

B-Cell vs. T-Cell Lymphoma in Dogs

Lymphoma cells come from one of two lymphocyte families, B cells or T cells, and a test identifies which. B-cell lymphoma is more common than T-cell. It also responds better to treatment, and on average, dogs with B-cell lymphoma live longer on treatment. Averages hide a lot, though. Some dogs with T-cell lymphoma achieve durable remissions. Some dogs with B-cell lymphoma don’t.

Breed plays into this too. AKC Canine Health Foundation-supported research found that Siberian Huskies, Alaskan Malamutes, Shar-Peis, Shih Tzus, and Lhasa Apsos are more likely to develop T-cell lymphoma, while Basset Hounds and Cocker Spaniels are more likely to develop B-cell lymphoma. Boxers and Golden Retrievers show an approximately equal number of occurrences of each.

What Are the First Signs of Lymphoma in Dogs?

The most common first sign of lymphoma in dogs is a firm, painless swelling of one or more lymph nodes. Often, the only noticeable sign is enlarged lymph nodes under the neck, behind the knees, or in front of the shoulders. Many affected dogs feel well when they are diagnosed with the common lymph node form.

A lymphoma node feels like a hard, rubbery lump under the skin. In the multicentric form, lymph nodes swell rapidly and without pain and may become 3 to 10 times their normal size. The node usually doesn’t hurt to the touch.

Not every swollen node is lymphoma. Because infections and immune-mediated diseases can also enlarge lymph nodes, further testing is needed to determine the cause. A needle sample helps a vet tell them apart.

Other Signs of Lymphoma in Dogs

Beyond the nodes, Purdue’s oncology team lists loss of appetite, lethargy, weight loss, swelling of the face or legs (edema), and occasionally increased thirst and urination. Some signs depend on the form:

• Drinking and peeing more. Lymphoma can raise blood calcium, which Merck describes as a syndrome seen in 10% to 40% of dogs with lymphoma, and a blood test can check for it.
• Vomiting, diarrhea, and weight loss are common in the alimentary form, which can look a lot like other stomach and intestinal illnesses.
• The mediastinal form can cause coughing, fast breathing, or working hard to breathe.
• The skin form can cause red, flaky, itchy, or sore patches of skin, sometimes with lumps in the skin or mouth.

These signs describe what vets see across many dogs. If a dog in your life has a new lump, a needle sample at a vet visit can answer the question. Our guide to a dog cancer diagnosis covers what that first appointment looks like and what to ask.

How Vets Diagnose Lymphoma in Dogs

Vets usually diagnose lymphoma in dogs by drawing a few cells from a swollen lymph node with a thin needle and examining them under a microscope. The most common test to diagnose lymphoma is fine-needle aspiration (FNA). It’s a quick test, done in the exam room at many clinics.

Sometimes the cells don’t give a clear answer. If the FNA results are inconclusive or the affected area is difficult to sample, your veterinarian may recommend a biopsy, which removes a small piece of tissue, usually under sedation or anesthesia.

Once lymphoma is confirmed, a few more tests can fill in the picture:

• Immunophenotyping, a test that identifies whether it’s B-cell or T-cell lymphoma, done by flow cytometry on a cell sample or by special stains on a tissue sample.
• Bloodwork and a urine test, which check your dog’s overall health and how well their body can handle treatment.
• Chest X-rays and an abdominal ultrasound, which look for lymphoma inside the body, in the chest, liver, or spleen.
• A bone marrow sample, which checks whether lymphoma cells have reached the marrow.

Not every dog needs every test. At Colorado State’s cancer center, completing all staging tests is not a requirement for treatment of dogs with lymphoma, and NC State asks for a diagnosis, recent bloodwork, and a urinalysis before treatment begins. If cost or your dog’s stress is part of the picture, ask what each test would tell you about your dog. Many families also see a veterinary oncologist, and a vet can refer you.

Stages of Lymphoma in Dogs

Lymphoma in dogs is staged from I to V based on how far it has spread, and each stage has a substage: a if the dog isn’t sick, b if they are. Stage and substage help a vet predict how a dog may respond to treatment. Vets use the World Health Organization system, which is routinely used to stage lymphoma in dogs, and in plain terms the stages look like this:

• Stage I is a single lymph node.
• Several lymph nodes on the same side of the body make it stage II.
• In stage III, lymph nodes on both sides of the body are involved, for example, under the neck and behind the knees on both sides.
• Once the liver, the spleen, or both are involved, it’s stage IV.
• Lymphoma outside the lymph nodes, in the blood, nervous system, or other sites, is stage V.

The substage can matter as much as the number. Substage a means not sick. Substage b means sick, with signs NC State lists as fever, eye inflammation (uveitis), or high calcium. Staging is not required for treatment. Beyond a diagnosis, recent bloodwork, and a urinalysis, testing can be tailored to your dog.

What Stage 4 and Stage 5 Lymphoma in Dogs Mean

Stage IV means the lymphoma has reached the liver or spleen. Stage V means it’s in the bone marrow, the blood, or another organ. The stage describes where the cells are, not a timeline.

Lymphoma that has reached the bone marrow or the gut is linked with a harder outlook, and AAHA’s 2026 oncology guidelines list it alongside T-cell type and substage b: Stage V (extra nodal, bone marrow, GI). If you’re weighing treatment, a vet can tell you what it might look like at your dog’s stage.

Lymphoma Treatment Options for Dogs

Chemotherapy is the main treatment for lymphoma in dogs because the disease runs through the whole body, and families also choose prednisone, comfort care, or euthanasia. VCA notes that surgery or radiation may suit lymphoma confined to one area, though most cases can’t be treated that way. Each path is below.

Multi-Drug Chemotherapy (CHOP)

CHOP is named for its drugs: cyclophosphamide, doxorubicin, vincristine, and prednisone. Purdue describes a 25-week protocol called CHOP, and Colorado State describes weekly visits for about four months, with treatment stopping if a dog stays in remission after 4 to 6 months and monthly rechecks after that. For high-grade multicentric lymphoma treated with a combination of drugs, Merck reports more than 90% of all dogs achieving complete remission. Complete means the cancer can’t be found with the usual tests for a time, and some dogs don’t respond.

At NC State, chemo visits are drop-off appointments: drop off between 7:30 and 8:30 a.m., and pick up by 6 p.m. IV drugs go in through a catheter. A small patch of hair will be shaved from your pet’s leg where the catheter is placed, so you may see a small bare spot afterward. Some treatments are given over a few minutes, some over 20-30 minutes, and some over several hours. Some doses are pills given at home.

Purdue reports that fewer than 5% of dogs treated for lymphoma using chemotherapy will experience side effects that need to be managed in a hospital setting. Some dogs have a harder time, with low appetite, tiredness, vomiting, or diarrhea for a day or two. A vet can send home anti-nausea medicine, adjust doses, or slow or stop treatment. Our guide to chemotherapy care at home covers feeding, rest, and day-to-day side effects.

Doxorubicin can cause hair loss, and breeds with consistently growing hair, like Poodles, Shih Tzus, Havanese, and Golden Retrievers, can develop what Purdue calls “chemo coat.” Hair grows back once chemo stops. Chemo can also lower white blood cell counts for a while, raising infection risk, and NC State says it will let families know if their dog is at risk.

Is Chemo Safe for People and Other Pets at Home?

Most chemo drugs leave the body in stool or urine at levels that pose little risk to people or other pets. If precautions are needed, your oncologist will let you know what precautions to take and if you are at risk. The usual precaution is to pick up stool right away, and a few take-home medications should be given with gloves. Purdue says oral chemo should be given whole with the use of medical grade gloves to avoid chemotherapy exposure. If a pill has been split, dissolved, or handled without gloves, the oncologist can tell you whether anything needs checking. If anyone in the house is pregnant or nursing, tell the oncologist, who can say what fits.

Single-Drug Chemotherapy

A single drug can mean fewer visits or a lower cost. NC State’s schedules give a sense of each:

• Doxorubicin, by IV every 2 to 3 weeks for 6 treatments.
• Rabacfosadine (Tanovea), by IV every three weeks.
• Lomustine (CCNU), a pill every three weeks.
• Verdinexor (Laverdia), a pill twice a week.

Doxorubicin alone can bring remission, with lower response rates than CHOP. Other common chemotherapeutic agents with activity against naive and relapsing lymphoma include lomustine, mitoxantrone, and rabacfosadine. Naive here means a dog who hasn’t had chemo yet, so these drugs can be part of a first plan or a later one.

What Can Prednisone Alone Do?

Prednisone is a steroid pill given at home, and it costs the least of the treatment paths. VCA notes that it can provide temporary relief and improve quality of life, and families choose it for reasons that include a dog’s overall health, cost, and practical considerations.

It also has side effects. VCA lists increased drinking, increased urination, and increased appetite, and at higher doses and with long-term use, vomiting, diarrhea, mild behavior changes, and panting. If prednisone is ever going to be stopped, a vet can explain how to taper it slowly to avoid complications, with a schedule for your dog.

If chemo is still being weighed, one detail matters: the AKC Canine Health Foundation notes that prednisone alone can make the disease resistant to other treatments. If your dog is already taking prednisone, tell the oncologist, who can say what it means for the plan.

What Comfort Care Means for a Dog With Lymphoma

Comfort care, also called palliative care, focuses on how your dog feels rather than on the cancer, with medicine for pain, nausea, and appetite. It can stand alone or run alongside any treatment, and our guide to palliative care vs. hospice for pets explains how the two differ. Our dog end-of-life guides cover hospice and euthanasia in more depth. On any path, treatment plans can be changed or stopped at any point, including moving from treatment to comfort care alone.

Keeping a Dog With Lymphoma Comfortable

Day to day, comfort care is practical work. Food comes first for many dogs. The primary dietary goal is to ensure that the food is highly palatable and consumed, according to AAHA’s oncology guidelines, so the aim is food your dog will eat. For poor appetite, the same guidelines list two appetite medicines, capromorelin and mirtazapine, and note that nausea is treated when it’s behind the problem.

VCA suggests hand-feeding as one option when a dog isn’t eating well. Blended or liquid diets may offer another alternative. For more ideas, our guide to appetite help for a terminally ill pet covers eating late in an illness.

Merck’s list of pain signs includes wanting to stay still or having trouble getting comfortable. Others include eating less, restlessness or anxiety, and hiding or withdrawing. If you notice any of these, tell a vet, because pain medicine is part of comfort care on every path.

Clinical Trials for Dogs With Lymphoma

Veterinary schools run trials of new lymphoma treatments, and some help with costs. Clinical trials offer another treatment option. The AVMA’s registry lets families and vets find veterinary clinical studies in the U.S. and Canada, and eligibility starts with a conversation with your dog’s vet.

How Much Does Lymphoma Treatment Cost for a Dog?

You can ask about cost at any point. NC State’s veterinary hospital publishes its own estimates for multicentric lymphoma:

• CHOP: $600 to $800 per treatment, or $6,000 to $8,000 over the whole protocol.
• Doxorubicin alone: $600 to $800 per treatment.
• Rabacfosadine alternating with doxorubicin: about $4,200 to $6,400 over the protocol.
• Lomustine (CCNU): $700 to $900 per treatment.
• Verdinexor: $300 to $500 a month, depending on body weight.
• Prednisone: $20 to $30 a month.

These are one hospital’s numbers, with one caveat: costs are estimates. Overall cost depends on patient response. They don’t include supportive care or hospital stays. For a national view, 2025 research done for CareCredit found the national average cost of therapy specifically for dogs diagnosed with lymphoma is $5,254, with state averages above and below that. Ask for an itemized estimate for the first month and for the full plan.

How Long Can a Dog Live With Lymphoma?

Every figure in this section describes groups of dogs on specific treatments, not your dog or the path you take. The type of lymphoma, its stage, and the treatment shape how long a dog lives with it, and with multi-drug chemo the median is about a year for B-cell lymphoma and shorter for T-cell.

A median is the middle point. Median survival means 50% of pets live less than that time point and 50% live longer. The published figures, path by path, from the veterinary sources cited in this guide:

• B-cell lymphoma on multi-drug chemo: about 12 months. On a standard protocol at NC State, dogs with B-cell lymphoma have a median survival time of 12 months, and Merck’s figure is about the same.
• T-cell lymphoma on multi-drug chemo: about 6 to 9 months.
• Multicentric lymphoma overall on CHOP: about 9 to 13 months.
• Prednisone alone or no treatment: about 1 to 2 months with prednisone at NC State and in AAHA’s guidelines, and about 4 to 6 weeks without treatment in Merck’s figures. VCA’s figure for both together is four to six weeks.
• Single drugs: about 6 to 8 months with doxorubicin alone, about 6 months with rabacfosadine, about 2 to 4 months with lomustine, and under 2 months with verdinexor.
• The most common type on the most intensive protocol: approximately 20% of dogs may live longer than two years at Colorado State.
• Low-grade lymphoma: Dogs with low-grade lymphoma tend to do well and with chemotherapy can survive longer than two years. These are the slow-growing forms.

Your dog’s type, stage, and substage decide which of these apply, and how a dog responds in the first weeks often tells more than any list.

What Happens When Lymphoma Comes Back

Remission means that the signs of lymphoma disappear; it does not mean that the cancer has been cured. In remission, swollen nodes shrink, and energy returns. Except in some slow-growing forms, Merck notes that eventual disease relapse is expected in most dogs, and over time the disease responds less to treatment.

Relapse isn’t always the end of treatment. Colorado State notes that the same drugs are often effective again, although the duration of remission is often shorter. Purdue adds that many dogs can achieve a second remission. At a relapse, one family tries more chemo, sometimes with the single drugs above, another moves to comfort care, and another chooses euthanasia.

Will a Dog With Lymphoma Die Naturally?

A dog with lymphoma can die naturally, and how it unfolds depends on the type of lymphoma, where it is in the body, and whether it’s treated. For other dogs, families choose euthanasia. Either way, if there’s time, a vet can help plan the end around comfort.

For dogs on chemo, the turning point is usually when treatment stops working. Purdue explains that most lymphomas eventually become resistant to chemotherapy, and that dogs with lymphoma die or are euthanized when the cancer can no longer be controlled with chemotherapy. Low-grade forms are different. They develop slowly, and dogs may not show any signs of the disease for a long time.

What End-Stage Lymphoma in Dogs Can Look Like

Where the lymphoma is located shapes the final stretch. In multicentric lymphoma, when there are several large tumors late in the disease, dogs may show general signs of illness, including lack of energy, weakness, fever, loss of appetite, and dehydration. When lymphoma in the chest advances, signs may include trouble breathing as fluid builds up in the chest. The breathing signs to know are further down this section.

Lymphoma outside the lymph nodes brings problems that follow the organ, which Merck lists as difficulty breathing (lungs), kidney failure (kidneys), blindness (eyes), seizures (central nervous system), and bone fractures and pain (bone). A dog may show some of these changes and not others.

Breathing trouble needs help right away. Cornell’s Canine Health Center lists signs of respiratory distress, including rapid breathing (often with an open mouth), a bluish tinge to the gums, the belly working hard with each breath, and the head and neck stretched out. If you see these, Cornell recommends that you take them to the nearest emergency animal hospital and call ahead if you can. If an emergency hospital is far away, call the nearest vet who can see your dog right away. These signs are about getting help now, not about how much time your dog has.

If your dog has already died, we’re so sorry. If a vet saw your dog, they may be able to talk it through with you. Our grief resources are here after a dog dies, whenever they’d help.

Planning for a Natural Death With Comfort Care

With hospice care, a vet plans with you for a crisis and for how your dog’s life ends, whether it be euthanasia or palliated death. A palliated death is a natural death in which a vet treats pain and other symptoms along the way. AAHA’s guidelines name palliative sedation as part of that conversation, so if you’re planning a natural death, you can ask what it would involve for your dog.

A few questions to bring to that conversation:

• Which changes would mean calling right away, and who answers after hours?
• What comfort medication should I keep on hand, and how do I give it?
• If breathing gets hard, what can be done, and where?
• Can someone come to me at home if I need help, whether that’s comfort care or euthanasia?

Some families choose euthanasia, and some hope for a natural death with comfort care. For comfort care, a vet can help you make a plan that can be adjusted as your dog changes. Our guide to in-home vs. clinic euthanasia compares the two settings. Our directory lists pet hospice care, in-home euthanasia, and veterinary clinics that offer end-of-life care, and you can contact a provider directly.

When to Say Goodbye to a Dog With Lymphoma

Families decide when to say goodbye to a dog with lymphoma in different ways. Some decide at diagnosis, some after one change like breathing, and some by watching the pattern of their dog’s days with a vet: eating, breathing, comfort, movement, and how their dog responds to them.

Merck’s guidance on pets with cancer says: Short-term issues, like pain, can often be managed, but there may come a time when the pet’s suffering outweighs the benefits of treatment. A quality-of-life scale can help you put words to what you’re seeing.

VCA describes one, created by veterinary oncologist Dr. Alice Villalobos, that scores seven areas: Hurt, Hunger, Hydration, Hygiene, Happiness, Mobility, and More good days than bad. Our guide to the HHHHHMM quality of life scale walks through each one, and the good days and bad days tracker keeps a simple daily record you can bring to appointments.

With lymphoma, a few things tend to come up in those conversations:

• Breathing, which VCA’s scale counts as part of pain control.
• Eating, and what might help.
• Energy, and how your dog responds to you and to the things they enjoy.
• Comfort, and whether medication is keeping your dog comfortable, including through the night.

Families say goodbye at diagnosis, at a relapse, on a calm day, or in a crisis. Our directory lists quality-of-life consultations if you’d like an outside view. Our guide to deciding when to say goodbye to your dog goes deeper into the decision itself.

Planning for a Dog With Lymphoma

If there’s time, some families write a comfort plan alongside the treatment plan for lymphoma in dogs. Lymphoma can bring many decisions in a short time, and writing down the comfort side, even on a single page, can make those decisions easier to hold.

It can help to ask a vet to lay out every path side by side: what chemo would look like for your dog, what prednisone or comfort care alone would look like, and what a natural death and euthanasia would each involve.

Then put what you learn on one page somewhere you’ll see it. Include the medicine schedule, the signs that mean call now, the after-hours number, the nearest emergency hospital, and what you’d want if things changed quickly.

Caring for a sick dog can be tiring, and many people start grieving while their dog is still with them. Our resources on anticipatory grief are there for that part. If you’d like someone to talk to, our directory lists pet loss grief counseling, and you can reach out to a counselor directly.

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