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Lymphoma in Dogs

Reviewed by Vanessa Farner, DVM on April 28, 2022

Canine lymphoma is the name for a common group of cancers in dogs. It starts in white blood cells called lymphocytes, which normally help the body’s defenses (immune system) fight off infections.

Lymphoma in dogs is similar to a type of cancer that people get called non-Hodgkin’s lymphoma. Chemotherapy is the main treatment for both.

Canine lymphoma usually can’t be cured. But chemotherapy could buy you and your pet more quality time together.

What Causes Lymphoma in Dogs?

Experts aren’t sure why dogs get lymphoma. They’ve looked into possible reasons like viruses, bacteria, chemicals, and even magnetic fields, but the cause still isn’t clear.

Some researchers think that genetic studies will eventually reveal clues.

What Are the Symptoms of Lymphoma in Dogs?

The most common sign you might notice is one or more firm, enlarged lymph nodes on your pet’s body. Lymph nodes are small glands that are part of your dog's immune system. When they're enlarged, they feel like hard, rubbery lumps under the skin. They’re not painful. They could show up in places like:

  • Under the neck or jaw
  • Behind the knees
  • In front of the shoulders
  • In the armpits

If you notice lumps like these on your dog, ask your vet to check them, even if your pet seems fine otherwise.

Lymphoma can also bring on symptoms like:

  • Reduced appetite
  • Tiredness
  • Weight loss
  • Swelling in the face or legs
  • Increased thirst
  • More frequent peeing
  • Diarrhea
  • Vomiting
  • Trouble breathing

If your dog has lymphoma, they may not seem sick. Or they may have only mild symptoms, like tiredness and loss of appetite. Your dog's symptoms, and how serious they are, are will depend on:

  • How advanced their cancer is
  • Whether it affects any of their organs
  • The type of lymphoma they have

What Are the Types of Lymphoma in Dogs?

Dogs can get over 30 types of lymphoma. They vary in how fast they spread, the symptoms they can bring on, and how long dogs tend to live with them.

Your vet might diagnose your dog with one of these four:

Multicentric lymphoma. This is the most common kind of canine lymphoma. Up to 85% of cases are this type, which first affects the lymph nodes. The main symptom you or your vet might notice is fast-growing enlarged lymph nodes.

Alimentary lymphoma (also called gastrointestinal lymphoma). The second most common type, it makes up less than 10% of cases of lymphoma in dogs. This type of lymphoma tends to affect dogs' intestines. It can cause symptoms like vomiting, belly pain, anorexia, diarrhea, and weight loss.

Mediastinal lymphoma. This rare type enlarges certain parts of the lymph system (tissues and organs that make, store, and carry white blood cells) in or around the chest. It can cause a lump or fluid buildup that makes it harder for your dog to breathe. They might also have a swollen face or front legs, be thirstier, and pee more.

Extranodal lymphoma (including cutaneous lymphoma). This type affects a specific organ or set of organs, like the skin, eyes, kidneys, lungs, or central nervous system. Most commonly, it affects the skin (called cutaneous lymphoma). It could bring on symptoms like growths or lumps called nodules, or scaly areas of skin. It may also affect the gums, lips, and roof of the mouth.

How Is Lymphoma in Dogs Diagnosed?

To find out if your dog has lymphoma, your vet may do a biopsy. They may start with a fine-needle aspiration, in which they use a thin needle to remove a sample from your dog’s lymph nodes or organs

They can also do another type of biopsy that involves minor surgery. They'll remove a piece of a lymph node or other organ that might have cancer in it, then send the sample to a lab for tests.

What Are the Stages of Lymphoma in Dogs?

If the results show your dog has lymphoma, your vet may recommend that your pet get staging tests. These show how far the cancer has spread. In general, the more body parts it involves, the worse the outlook for your dog’s health.

Staging tests include blood tests, pee tests, X-rays, ultrasounds, and more.

The five stages of canine lymphoma reflect the extent of the cancer in your dog’s body:

  • Stage I: A single lymph node is enlarged.
  • Stage II: More than one node is enlarged on either the front half or back half of your dog’s body.
  • Stage III: More than one node is enlarged on both the front and back of your dog’s body.
  • Stage IV: The lymphoma has reached the liver, spleen, or both.
  • Stage V: The lymphoma affects the bone marrow or other organs (like the gut, skin, or nervous system).

Each stage can also be divided further. Your vet may use the term “substage A” to mean your dog feels well, and the term “substage B” to mean they’re sick.

How Is Lymphoma in Dogs Treated?

Learning that your dog has cancer can be heartbreaking. But treatment could extend their life.

The most effective treatment for lymphoma in dogs is chemotherapy. There are many chemo drugs. The ones your vet recommends for your pet will depend on the type of lymphoma they have.

Some chemo drugs are given to dogs through an IV and some are given by mouth. Dogs often get a combination of these meds.

Your dog may need weekly chemo treatments for several months.

Dogs don't usually get very sick from chemo or lose their hair the way some humans do. Some common side effects are:

  • Loss of appetite
  • Being less active
  • Vomiting or diarrhea that lasts for a day or two

Always call your dog’s vet or cancer doctor if they have severe side effects. They may be able to prescribe medicines that will help.

Along with chemo, vets sometimes recommend treatments like radiation therapy or surgery.

Ask your vet to walk you through your dog’s treatment options. Have them explain the pros and cons of each. Together, you can decide what treatment (if any) is right for your dog.

What’s a Dog’s Life Expectancy After Lymphoma Treatment?

Your dog's life expectancy depends on things like the stage of their cancer and what treatment they get.

Most dogs who get chemotherapy for lymphoma go into remission. “Partial remission” means that some, but not all, of your dog’s signs of cancer have gone away. “Total remission” means all symptoms of the disease have disappeared, although cancer could still be in their body.

Neither type of remission is a cure. But often, dogs who get lymphoma treatment go into total remission for many months. According to one estimate, most dogs with lymphoma that affects their lymph nodes have an initial remission that can last 6-9 months.

Lymphoma in dogs usually comes back, though. Your vet may call this a “relapse.” Treatment helps some dogs get back into remission. But when the cancer returns, it’s harder to treat. In the end, the disease is fatal.

Keep in touch with your vet while your dog gets lymphoma treatment or recovers from it. They can let you know what to expect if the disease gets worse, and how to keep your pet as happy and comfortable as possible. You can also ask the vet about hospice care and euthanasia (putting your dog to sleep) to help them pass away peacefully when the time comes.

Show Sources

SOURCES:

American Kennel Club: “Lymphoma in Dogs: Symptoms, Diagnosis, and Treatment.”

Purdue University: “Canine Lymphomas.”

Washington State University: “Lymphoma in Dogs.”

Colorado State University: “Lymphoma in Dogs.”

University of Florida: “Lymphoma in Dogs.”

American Cancer Society: “Chemotherapy for Non-Hodgkin Lymphoma.”

National Cancer Institute: “Lymph System.”

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