Canine lymphomas are unfortunately among the most common cancers diagnosed in dogs, comprising 7% to 14% of all canine cancers.

Canine lymphomas are similar to non-Hodgkin’s lymphomas which occur in humans, according to the Purdue University College of Veterinary Medicine. Both are identical in appearance (under the microscope) and have a similar response to chemotherapy.

Scientists have identified over 30 types of canine lymphoma, which can vary in behavior. Some develop more quickly and are life-threatening without treatment, while others develop more slowly and can be managed as a chronic disease.

With lymphoma estimated to affect 1 in 15 dogs, it’s important to be informed about what causes it, the symptoms to look out for, and how to treat it.

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What Is Lymphoma in Dogs?

Lymphoma is a cancer of the lymphocytes, a type of white blood cell that is part of a dog’s immune system.

Lymphocytes can be found in nearly every organ of the body, but the most common locations are the lymph nodes, spleen and bone marrow.

The role of the lymphocytes is to help fight infection in the body, but if they mutate, they can multiply and cause the lymph nodes, spleen, and other organs to become enlarged.

“It is one of the most common cancers in dogs with the most common form being multicentric lymphoma (affecting multiple lymph nodes),” says Dr. Daniela Korec D.V.M., oncological advisor to Dr. Cuddles, a pet care company. “Lymphoma can also impact other organs like the spleen, liver, intestines, central nervous system, and bone marrow.”

While multicentric lymphoma comprises around 80% of diagnosed canine lymphoma cases, the following types of lymphoma represent about 5% of canine lymphomas:

  • Mediastinal (enlarged lymph node in the chest)
  • Cutaneous (skin)
  • Extranodal (bone, eyes, liver)
  • Gastrointestinal (also called alimentary lymphoma)

At this point, doctors don’t know what causes lymphoma in dogs, but have investigated several possible causes:

  • Viruses
  • Bacteria
  • Chemical exposure
  • Physical factors, including strong magnetic fields

While scientists have been able to directly connect the development of lymphoma with the suppression of the immune system in humans, this connection hasn’t been proven in dogs.

Symptoms and Behaviors of Dogs With Lymphoma

There are a range of symptoms dogs can experience with lymphomas.

“Symptoms of lymphoma depend largely on the type of lymphoma, the organ system involved, and how advanced the stage,” says Dr. Rebecca Greenstein, D.V.M. veterinary medical advisor for Rover.

Dogs with lymphoma can show normal behavior and minimal clinical signs, notes Dr. Casey Robinson, D.V.M., area medical director at IndeVets, a veterinary staffing service that partners with animal hospitals.

“Perhaps the most noted sign that leads to a veterinary visit is specific areas of swelling,” he adds. “These areas represent lymph nodes that become enlarged secondary to the cancerous process.”

Multicentric Lymphoma Symptoms

The most common sign of multicentric lymphoma in dogs is firm, enlarged, non-painful lymph nodes.

An affected lymph node will feel hard, rubbery and like a lump under the dog’s skin. The most easily accessible lymph nodes on your dog will be the ones located under the jaw and behind the knee.

Other common symptoms of multicentric lymphoma include:

  • Loss of appetite
  • Lethargy
  • Weight loss
  • Swelling of the face or legs
  • Increased thirst and urination

Cutaneous Lymphoma Symptoms

The most common signs of cutaneous lymphoma in dogs include dry, flaky, red and itchy patches of skin that can appear anywhere on the body.

As the cancer further develops, the skin then becomes moist, very red, thickened and ulcerated. Dogs may also experience masses with this type of lymphoma.

Oftentimes, cutaneous lymphoma progresses slowly and is treated for several months as an infection or allergies before doctors determine the cause as lymphoma.

Cutaneous lymphoma can also affect the dog’s gums, lips and the roof of their mouth, which is commonly mistaken for periodontal disease or gingivitis during the early stages of the disease.

Gastrointestinal Lymphoma Symptoms

The most common signs of gastrointestinal lymphoma in dogs include:

  • Loss of appetite
  • Vomiting
  • Diarrhea
  • Weight loss
  • Lethargy

Mediastinal Lymphoma Symptoms

The most common sign of mediastinal lymphoma in dogs is difficulty breathing. This is typically due to a mass in the chest or the accumulation of fluid in their chest.

Other common symptoms of mediastinal lymphoma include:

  • Swelling in the face or front legs
  • Increased thirst
  • Increased urination

How To Test for Lymphoma in Dogs

Lymphoma is diagnosed with a biopsy, which is a minor surgical procedure that removes a piece of a lymph node or other organ that is suspected to be affected by the cancer.

The most common methods for lymph node biopsy are:

  • Tru-cut needle biopsy: This type of biopsy is minimally invasive and is done under a local anesthetic.
  • Incision wedge biopsy: This type of biopsy uses a sharp blade to remove a sample of tissue via a wedge. This tends to cut deep into the skin and even sample subcutaneous fat. It is done under local anesthetic.
  • Removal of an entire lymph node (excisional biopsy): This type of biopsy involves general anesthesia and is an outpatient procedure.

With a biopsy, dogs are usually under heavy sedation or general anesthesia. After the biopsy, pain and discomfort is typically minor, but veterinarians often prescribe oral pain medication to ensure the dog is comfortable.

Because lymphomas involve the lymph nodes, which are located throughout the body, it can spread to nearly any tissue in the dog’s body. This is why most veterinarians will require a thorough diagnostic examination to determine the stage of the cancer.

Unfortunately, the prognosis is less positive if the cancer has spread to more places in the dog’s body. However, treatment is still possible and dogs can experience remission.

Cancer staging diagnoses usually involve the following tests:

  • Blood tests
  • Urinalysis
  • X-rays of the chest and abdomen
  • Abdominal sonogram
  • Bone marrow aspirate

What Are the Stages of Lymphoma in Dogs?

Canine lymphoma is categorized into five stages, which is determined by how far the cancer has progressed in the dog’s body.

“The stage at the time of diagnosis has a bearing of prognosis for the patient,” Robinson says. “The time it takes to progress from one stage to the next will vary for every patient.”

Stage Description
I
Involves a single lymph node, or lymphoid tissue in a single organ.
II
Involves multiple lymph nodes in either the front half or back half of the dog’s body.
III
Involves multiple lymph nodes on both the front half and back half of the dog’s body.
IV
Involves the liver and/or the spleen.
V
Involves bone marrow, or other organs, including gastrointestinal, skin, nervous system.

Each of the stages is further broken down into two subcategories:

  • Substage A: the patient feels well
  • Substage B: the patient does not feel well

Treatment for Canine Lymphoma

There are several treatment protocols for dogs with lymphoma, including the CHOP protocol, which is the most common and most effective for canine lymphoma, Korec says.

The CHOP protocol includes:

  • Cyclophosphamide: An alkylating agent taken orally.
  • Doxorubicin (Hydroxydaunorubicin): An anthracycline antibiotic with anti-tumor activity. This is given through IV.
  • Vincristine (Oncovin): A vinca alkaloid taken orally.
  • Prednisone: A corticosteroid taken daily, orally.

The estimated cost of the CHOP protocol is $400 to $500 per treatment, with a total cost of $4,500 to $5,500 over the course of the 15 week treatment.

Other types of treatment are usually determined by the owners, what the pet needs and the type of lymphoma.

“If your dog is diagnosed with lymphoma, your veterinarian or veterinary oncologist will outline the various treatment options that are available to your pet,” Robinson notes.

Treatment for cancer can occur on a weekly or bi-weekly basis, and some can be as far apart as every three weeks.

Factors that will determine the type of treatment chosen for canine lymphoma include the following:

  • The type of lymphoma
  • The dog’s overall health
  • Stage of cancer at diagnosis
  • Owner’s circumstances

Treatment Costs for Dogs With Lymphoma

The total cost for treating lymphoma in dogs will vary depending on a variety of factors, including the following:

  • How early the cancer was diagnosed
  • What stage the cancer is
  • The dog’s overall health
  • Where you live
  • The level of care/intervention required

Korec notes the average total cost of treating lymphoma in dogs can be anywhere from $3,700 to upwards of $10,000.

The costs associated with treating lymphoma in dogs include the following:

  • Diagnostic tests, including blood tests, biopsies, and imaging: $500 to $1,500 and up
  • Follow-up care and medications: $200 to $500 and up
  • Veterinary oncologist initial consultation: $125 to $250
  • Chemotherapy: $150 per dose to $600 per dose
  • Radiation (palliative): $1,000 to $1,800
  • Radiation (curative): $4,500 to $6,000

Dogs often handle chemotherapy treatment better than humans, Korec says, largely due to the differences in dosing and the goals of treatment.

“Veterinarians typically aim to preserve quality of life while treating cancer, so the doses of chemotherapy drugs used in dogs are usually lower than those used in humans and most protocols administer one drug at a time rather than multiple,” she notes.

As a result, 95% of dogs undergoing chemotherapy have mild or no side effects at all.

Some of the most common side effects of chemotherapy include the following:

  • Mild nausea
  • Decreased appetite
  • Vomiting
  • Diarrhea
  • Low blood cell counts

Side effects are often managed using medications like anti-nausea drugs and appetite stimulants, as well as regular monitoring, including blood tests and check-ups.

“As quality of life, not length of life, is typically the most important factor for dogs we are treating,” Korec says. “If an animal is experiencing adverse side effects, therapy can be stopped or the protocol changed to ensure that they are maintaining the best quality of life for as long as possible.”

Is Lymphoma Covered by Pet Insurance?

Whether your pet insurance covers treatment for lymphoma will depend entirely on your individual coverage plan and if  your dog was diagnosed before or after the coverage started.

“It is important to read the fine print of the policy to be sure it does cover cancer and other illnesses,” says Dr. Wendy Hauser, D.V.M., founder of Peak Veterinary Consulting and special advisor to ASPCA Pet Health Insurance.

“With illness coverage, most pet insurance providers consider cancer like lymphoma as an eligible expense if the dog develops the condition after the policy is in place,” she adds.

There are also some pet insurance companies that cover pre-existing conditions with limitations.

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What Is the Life Expectancy of Dogs With Lymphoma?

The life expectancy of dogs with lymphoma varies depending on the type of lymphoma they have, the stage at diagnosis and the treatment provided.

“Dogs that receive minimal to no treatment unfortunately have a median survival time of 6 weeks or less—however, some may live longer,” Robinson says.

With chemotherapy, dogs can go into remission, with a median survival time of 6 to 12 months. Roughly 20% of dogs that receive chemotherapy might live for two years or longer, Korec says.

“Advanced treatments can potentially extend this further, although many of these approaches are still in their early experimental stages,” Korec adds.

Is Lymphoma Common in Senior Dogs?

While lymphoma is a common cancer among middle-aged to older dogs, younger dogs can also get lymphoma.

In addition, certain breeds are at an increased risk for lymphomas, including the boxer, Rottweiler, and golden retriever. But lymphoma can affect any breed of dog.

Other Common Health Conditions in Dogs: