Lymphoma in Dogs and Cats: Signs, Diagnosis, and Treatment

Hearing that your dog or cat may have cancer is difficult. With lymphoma, however, many pets respond well to treatment, and your veterinary team can help you understand the diagnosis and available options.

Lymphoma signs can include enlarged lymph nodes, changes in appetite or weight, digestive problems, low energy, or breathing changes. The signs vary because lymphoma can develop in several areas of the body.

What Is Lymphoma in Dogs and Cats?

Lymphoma is a cancer of lymphocytes, a type of white blood cell that helps the immune system. Lymphocytes are found throughout the body, including in the lymph nodes, spleen, gastrointestinal tract, and other tissues.

In dogs, lymphoma commonly affects the lymph nodes. In cats, lymphoma often involves the gastrointestinal tract. It may also develop in the spleen, liver, kidneys, skin, or chest.

The type of lymphoma, how quickly it is growing, how extensive the disease is, and how it responds to treatment guide the outlook and treatment plan.

Signs of Lymphoma in Dogs

The most common form of lymphoma in dogs affects the lymph nodes. Enlarged lymph nodes may feel like firm, non-painful lumps beneath the skin, especially under the jaw, in front of the shoulders, or behind the knees.

Some dogs with enlarged lymph nodes still feel well, which can make lymphoma difficult to recognize early.

Other signs of lymphoma in dogs may include decreased appetite, weight loss, low energy, increased thirst or urination, vomiting, diarrhea, or changes in breathing.

An enlarged lymph node does not always mean a dog has lymphoma. Infections, inflammation, and other conditions can also cause lymph nodes to enlarge. Your veterinarian can recommend testing to determine the cause.

Signs of Lymphoma in Cats

Signs of lymphoma in cats often look like digestive problems, especially when the gastrointestinal tract is involved. Cats may eat less, lose weight, vomit, have diarrhea, or seem less active.

Some cats have slower-growing gastrointestinal lymphoma that causes signs to come and go, so the condition may not be suspected right away.

Lymphoma in cats can also cause breathing changes, increased thirst or urination, unusual lumps or skin changes, or shifts in normal behavior.

Because cats often hide pain and illness, persistent vomiting or diarrhea, reduced appetite, or unexplained weight loss should be checked by a veterinarian.

How Is Lymphoma Diagnosed?

If your veterinarian suspects lymphoma, testing helps confirm whether cancer is present and, when possible, identify the specific type.

When enlarged lymph nodes or another accessible mass is present, a fine-needle aspirate is often one of the first tests performed. During this procedure, a small sample of cells is collected with a needle and examined by a veterinary clinical pathologist. Additional testing, such as flow cytometry or Polymerase Chain Reaction for Antigen Receptor (PARR), may be recommended based on these results.

In some cases, a biopsy is needed to confirm the diagnosis or provide more information about the type of lymphoma. This information can be important because different types of lymphoma may respond differently to treatment.

Bloodwork and imaging, such as chest X-rays or an abdominal ultrasound, may also be recommended. These tests help evaluate your pet’s overall health and look for other areas of involvement. Together, they help your veterinary team stage the lymphoma.

How Is Lymphoma Treated?

Chemotherapy is the primary treatment for many types of lymphoma in dogs and cats because cancer cells may be present in more than one area. Surgery is generally not enough to control lymphoma because removing an enlarged lymph node or affected organ does not eliminate cancer cells that may be present elsewhere in the body.

The chemotherapy protocol depends on the type of lymphoma and stage, your pet’s overall health, and other individual factors. Your veterinary oncologist can explain the recommended treatment, schedule, monitoring, and what to expect at home.

Veterinary chemotherapy is designed to treat the cancer while helping pets maintain a good quality of life.

Most dogs and cats tolerate chemotherapy well. Possible side effects include decreased appetite, vomiting, diarrhea, or temporary tiredness. Significant hair loss is uncommon in most dogs and cats, although some breeds can experience hair loss or coat changes. Your veterinary oncology team will monitor your pet and can adjust medications or the treatment protocol if needed.

For most pets with lymphoma, the goal is remission rather than cure. Remission means the lymphoma is no longer detectable with the tests being used. If it returns, additional therapy may still be an option based on the initial response.

What Is the Prognosis for Dogs and Cats with Lymphoma?

The prognosis for lymphoma in dogs and cats varies depending on several factors. Lymphoma type, disease stage, overall health, and response to treatment all influence the outlook.

Many pets respond to chemotherapy and achieve remission, though the length of remission varies. Your veterinary oncologist can provide a more specific prognosis after reviewing diagnostic and staging results.

Quality of life remains an important consideration throughout treatment. The care plan can be adjusted based on your pet’s response and comfort.

If your pet has signs that may be related to lymphoma, start with your family veterinarian. If lymphoma is diagnosed or suspected, MedVet’s board-certified medical oncologists and radiation oncologists can work with you and your family veterinarian to explain the diagnosis, review treatment options, and guide the next steps in your pet’s cancer care.

Learn more ways to keep your pets healthy and safe.

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