What You Need to Know About Lymphoma in Dogs

Just like humans, dogs can be vulnerable to cancer, particularly as they age. Luckily, modern veterinary science has many ways of treating dog cancers. It’s still wise to be informed so you can know what to expect if your dog is diagnosed with dog lymphoma, which accounts for roughly seven to 14 percent of all dog cancers and is one of the five most common for dogs.

Lymphoma in dogs is similar to non-Hodgkin’s lymphoma in humans, but there are more than 30 described variations and they can vary significantly in their behavior. Read on for signs, symptoms, breed vulnerability, and treatments of the most common types of dog lymphoma.

What is Lymphoma in dogs?

A lymphoma arises from white blood cells called lymphocytes, which normally help the immune system fight off infections. Most lymphomas are found in organs that are part of the immune system.

Alhough it can be found in any organs, it’s most often seen in the lymph nodes under the jaw, in front of the shoulders, or behind the knee (sometimes called the stifle). From there, it can spread to another organ, such as the spleen, liver, or into the dog’s bone marrow. Some lymphomas progress rapidly and require aggressive treatment, while others move very slowly and can be managed as a chronic disease. Like most dog cancers, lymphoma has no known cause, but it is likely the result of a mix of genetic and environmental influences.

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Are certain breeds predisposed?

Lymphoma can develop in any breed at any age, though Golden Retrievers seem to be the most commonly affected, followed by Boxers, Bullmastiffs, Basset Hounds, Saint Bernards, Scottish Terriers, Airedales, and Bulldogs.

The four most common types of lymphomas are multicentric (80 to 85 percent of lymphomas), affecting the lymph nodes; alimentary (seven percent of lymphomas), affecting the intestines; mediastinal, affecting the thymus and nodes in the chest; and extranodal, affecting a specific organ, such as the skin, eyes, kidneys, lungs or central nervous system. If the bone marrow is involved, the diagnosis is lymphocytic leukemia.

Symptoms of lymphoma in dogs.

In lymphoma’s early stages, the dog might not be showing any signs of illness, but their owner could notice a lump under the jaw or in the dog’s neck. The symptoms of lymphoma in dogs that could present themselves are: mild tiredness or a reduced appetite ranging up to more serious symptoms, such as weight loss, weakness, GI problems, excessive thirst, or difficulty breathing. Swollen, non-painful lymph nodes are a consistent sign that the dog needs to be seen by a vet.

Lymphomas that appear on the skin (cutaneous lymphomas) are sometimes first diagnosed as an infection or an allergy; they start with red, flaky, itchy patches that eventually become red, moist, open sores. Gastrointestinal lymphomas present with vomiting; dark, watery diarrhea; and weight loss. Lymphomas that appear in the chest can cause a dog to have difficulty breathing and/or to develop a swollen face and front legs.

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How is it diagnosed?

To diagnose lymphoma, the vet will biopsy the affected tissue and follow up with a series of tests to determine how far it has developed. Blood and urine are evaluated, the chest and abdomen are X-rayed, and a sonogram of the abdomen and a bone marrow aspirate may be recommended.

If a sonogram reveals abnormalities, the next step is often taking a sample of the affected area via fine needle aspirate, which is a relatively easy way to obtain a specimen for the patient.

What is the treatment for dog lymphoma?

Depending on the type, lymphoma is generally considered to be treatable, and chemotherapy is the preferred method.

According to experts at Colorado State University’s Flint Animal Cancer Center, “Canine lymphoma is initially very sensitive to chemotherapy. Up to 95 percent of dogs treated will go into remission when the most effective treatment protocols are used.”

Your dog would be given a mix of drugs to treat the lymphoma over several weeks to several months, depending on the case, which is pretty much how lymphomas are treated in people.

A recent therapy, Tanovea-CA1, which has received conditional approval from the Federal Drug Administration (FDA), is very promising. It can be used alone or in combination with other drugs and involves five intravenous infusions of the drug at 21-day intervals. The drug is expensive but can result in a lower overall cost because it can shorten the course of treatment.

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The FDA has also announced conditional approval of a new oral drug to treat canine lymphoma. Laverdia-CA1 (verdinexor tablets), which can be administered at home, works by preventing cancerous cells from spreading. According to the FDA, “Conditional approval allows veterinarians to access needed treatments while the drug company collects additional effectiveness data, such as through trials with client-owned dogs. The company then has up to five years to complete effectiveness studies to support a full approval.”

Dogs treated for lymphoma tend to have a very good quality of life and often remain in remission for a year or more. Roughly 20 percent of dogs survive more than two years with appropriate treatment.