Lymphoma is one of the most common cancers of dogs. It is cancer that derives from the cells in the lymph system, which is comprised of the lymph nodes and circulating lymphocytes in the vascular system. Although lymphoma can affect virtually any organ in the body, it most commonly arises in organs that function as part of the immune system such as the lymph nodes, spleen, and bone marrow. By far the most common type of lymphoma in the dog is multicentric lymphoma, in which the cancer is usually first noticed in lymph nodes. Lymphoma is also one of the most well-understood cancers in dogs, with regard to diagnosis, treatment options, and prognosis. It is one of the few cancers in dogs that can have remission times of years, and although it is not frequent, a cure is sometimes a possibility.



The cause of lymphoma is not well understood. Certain breeds of dogs, such as Golden Retrievers, are at higher risk of getting lymphoma. Therefore, it is believed that there is a significant genetic component to lymphoma. However, any breed of dog, at any age, including juvenile dogs, can get lymphoma. It is also believed that there are environmental contributors to lymphoma. Environmental factors such as chemicals, airborne pollutants, and other variables may damage cells. As dogs age, the cellular repair is slower, and cancer becomes more prevalent. Other than protecting our dogs from known predispositions or causes of cancer such as secondhand smoke, or certain chemicals, we really cannot prevent our dogs from getting lymphoma.


SYMPTOMS OF CANINE LYMPHOMAThe symptoms of lymphoma are variable and tend to mimic the symptoms of many other diseases or disorders, but will also depend on the cancer’s location and how advanced it is. Commonly observed findings are pronounced enlargement of the lymph nodes on the underside of the dog’s neck, slightly behind the chin. Dogs may also show signs of one or more of the following:

  • Weight loss
  • Lethargy
  • Loss of appetite
  • Constipation
  • Vomiting
  • Diarrhea
  • Shortness of breath
  • Fever
  • Increased thirst
  • Increased urination
  • Difficulty swallowing
  • Skin nodules or masses



Lymphoma can be detected via several pathways. Sometimes, a dog is just not feeling well. Sometimes an owner or a veterinarian detects enlarged lymph nodes. Sometimes a veterinarian will detect an abnormal finding on a routine physical exam, such as an enlarged spleen or liver.

When a dog is diagnosed with lymphoma and is feeling ill (the dog is showing signs of loss of appetite, weight loss, lethargy, or the like) this means that the lymphoma is classified as “b”. This does not refer to the type of lymphoma, but merely to the fact that the dog feels ill. If lymphoma is diagnosed and the dog feels well (no noticeable symptoms of illness), then the lymphoma is classified as “a”. Dogs that are diagnosed with lymphoma generally tend to respond more favorably to treatment if they are feeling well (a). However, depending on the stage and type of lymphoma, dogs that are ill (b) may respond very favorably to treatment as well.

There are five stages of lymphoma in dogs. They are classified as stages I through V. These stages are identified based on diagnostic tests such as a physical exam, blood work, radiographs, ultrasound, and bone marrow biopsy. Additional blood or bone marrow testing may further identify lymphoma as B or T cell lymphoma. The stages of lymphoma in dogs are essential as follows:

  • Stage I – only one lymph node (or lymphoid tissue in one organ) is involved
  • Stage II – multiple lymph nodes or a chain of lymph nodes in a localized area are involved
  • Stage III – Widespread, generalized lymph node involvement; most or all peripheral lymph nodes are affected
  • Stage IV – any or none of the above, plus liver and/or spleen involvement
  • Stage V – any or none of the above, with bone marrow involvement, blood involvement or involvement of any non-lymphoid organ

All of this information is distilled onto a classification of the general disease. For example, a dog may be diagnosed with Stage IV b, B cell lymphoma. This means that the liver and spleen have cancerous cells in them (indicating systemic metastasis), that this dog is feeling ill from the lymphoma, and that the B cell lymphocytes are the cell of origin. Another example would be stage V b T-cell lymphoma. The higher the stage number, the more disseminated the cancer cells are throughout the body. The cell type can be important, as B and T cell lymphomas behave differently, and respond differently to chemotherapeutic treatment.


Canine Treatment

Depending on the age of diagnosis, and the stage and type of lymphoma, the diagnosis of lymphoma is not a death sentence. In fact, lymphoma is amongst the most highly treatable cancers that occur in dogs.

The mainstay of treatment for dogs with lymphoma is the administration of chemotherapy. Chemotherapy is the use of chemicals (medication) to treat disease – more specifically; it usually refers to the destruction of cancer cells. The best responses in terms of length of tumor control and survival are generally seen with protocols that entail administration of more than one chemotherapy drug, although there are approaches that involve the administration of a single drug.

In the treatment of dogs with cancer, it is usually to put the disease into remission to prolong life and to assist in a better quality of life. Chemotherapy protocols are complicated and rapidly evolving. A veterinarian oncologist is the best person to discuss your options and advice on treatment for canine lymphoma.

Another form of treatment less commonly used is radiation. The exploration of radiation therapy, used in conjunction with chemotherapy is finding new avenues in the treatment of canine lymphoma. Early research suggests that the combination of the two improve remission rates and can extend the disease-free interval in dogs with multicentric malignant lymphoma.

There are quite a few options for the treatment of lymphoma. They range from very inexpensive medications that will often create a state of remission for a short time, to more impactful, costly therapies that can drastically increase median survival time. More aggressive chemotherapy is associated with an increased risk of adverse effects such as nausea, malaise, or infections secondary to immune suppression. The more aggressive protocols are also more costly, and more intensive. However, overall, the more aggressively lymphoma is treated, the longer your dog will survive. In spite of the possibility of adverse side effects, many dogs have a very good quality of life for the majority of treatment. “Bumps in the road” such as infections, or nausea, can be dealt with medically most of the time. Finances are a fair consideration, and it is very important that dog owners make these choices with finances in mind. Many dog owners feel guilty if they cannot afford the most ideal treatment option. However, veterinarians understand this consideration and support any decision that an owner makes that is well informed and honest. It is important to make the best decision that is feasible and to place positive energy toward that path.


If your dog is diagnosed with lymphoma, obtain all the information that you can. Speak with your veterinarian about treatment options. Inquire as to whether a veterinary oncologist might be helpful. Consider your personal finances with the respect that they are due, and realize that your choice is multi- factorial, and does not directly reflect the degree of love that you have for your dog. Each patient is an individual, as is the owner of each dog that is ill.


You and your veterinarian are partners in keeping a watchful eye on your pet’s health. Paying close attention to your pet’s habits will key you in when there may be a problem. Pay attention to those impressions that your pet seems “off”. Make a routine of checking your pet’s gum color, eyes, ears and mouth. Run your hands over their body periodically to make sure there are no new growths or tender areas. Weight loss may be evident over the spine and ribs. Bring your concerns to your veterinarian, especially if it they have not had a checkup within the past 6 months to a year. Remember that a year in a dog’s life is equivalent to 7 or so years in our life. This is why a good physical exam should be conducted yearly on a dog in their early years of age and twice when over 7(when they hit their fifties!).

Before visiting your veterinarian, write down all of your concerns and questions. As our pet’s advocate, this is so important as we are their voice and we tend to forget when the consultation begins. After a medical history is taken, the physical exam begins. A good physical examination by your veterinarian will include palpation of lymph nodes, oral exam, chest auscultation and palpation of the abdomen for abnormalities and evidence of bone or joint pain. Blood work and urinalysis may be recommended to screen for internal organ dysfunction. Fine-needle aspiration may be conducted of lumps to determine their nature. Many soft tissue tumors turn out to be benign lipomas (a benign tumor made up of fatty tissue). These are usually not a problem unless they are in an area that causes a problem with mobility (the armpit or near a joint). It is good to check these and document that they are not problematic and it gives one peace of mind. Don’t just assume a mass is a lipoma. Have it checked out.


It is important to take a holistic approach to cancer treatment. You may choose to consult with a veterinary oncologist, a specialist in cancer medicine for dogs and cats. They can present the latest research and treatments offered in Western veterinary medicine. Isn’t it interesting to note that many chemotherapy and anti-infective agents are derived from natural origins? Herbal medicine has a multitude of compounds that are helpful in treating and preventing cancer such as turmeric, green tea/polyphenols, mushroom polysaccharides, and a multitude of others. It is overwhelming looking into supplements for treating cancer and they can easily take over your pet’s food bowl. There are so many that are potentially helpful and how do you know their quality and efficacy?

A holistic veterinarian trained in herbal medicine, acupuncture, homeopathic medicines, and other complementary modalities can help look at your pet’s unique situation and help prioritize which therapies would be most helpful. They should coordinate alternative therapies with your conventional veterinarian or oncologist. They can also guide you in the selection of a diet that is suitable for cancer patients. Cancer tends to take over the metabolism and cause weight loss. It is important to feed a diet that has fewer carbohydrates and more quality protein as well as antioxidants and omega fatty acids. There are many resources available such as acupuncture for pain, nausea caused by chemotherapeutic agents and to improve overall well being. To find a holistic veterinarian certified in these modalities you can go to:


One of the most difficult tasks a veterinarian faces is to inform a pet owner that their beloved friend has cancer. Pet owners are faced with this diagnosis more often than you would think. It is estimated that 50% of dogs will be diagnosed with cancer at some point in their lifetime.

Today’s pets are living longer due to an increased focus on preventive medicine. In addition advances in medicine have also added to pets living longer than ever, thus opening the door to age-related conditions. Environmental influences such as toxins (pesticides, herbicides, and air pollutants), processed foods, and food additives, vaccinations, and genetic influences have all been blamed as causative factors.

There are many factors that can help decrease the likelihood of cancer: (annual wellness examinations), judicious vaccination, diet, exercise, avoidance of potential toxins in the environment, and of course, good genes. Just like anything else in life, there is no guarantee of health despite our best efforts to maintain it. What we do know is that pets have demonstrated an overall positive effect on our health. They help increase our physical and mental health by their mere presence. We gladly do our best to promote theirs.