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What is lymphoma?

Lymphoma is the abnormal proliferation of lymphocytes which are one of the main types of white blood cells involved in immunity. Lymphoma usually arises in lymphoid tissues such as lymph nodes, spleen, and bone marrow. However, lymphoma may arise in any tissue in the body.

Will my dog be sick?

Often owners will notice enlarged lymph nodes in dogs with no apparent signs of illness. Some dogs will show signs of illness, which will vary depending on the extent and location of lymphoma. 

My dog has enlarged lymph nodes but appears normal. What does this mean?

Most dogs with enlarged lymph nodes have lymphoma. Unfortunately, an inflammatory or infectious cause is rare, even in dogs with extremely irritated skin. The majority of lymphomas are high-grade and rapidly progressive. If left untreated, most dogs reach terminal stages one to two months from presentation. However, with chemotherapy, the majority of dogs will achieve complete remission (i.e. the disappearance of all signs of cancer) and have an excellent quality of life. Around 10% of dogs are permanently cured by combination chemotherapy.

How do I check if my dog has lymphoma?

Diagnosis is usually confirmed with sampling the affected organ and lymph nodes by either cytology (fine needle aspirate samples) or biopsy (tissue sample). Further testing with B & T cell immunophenotyping is often recommended to determine if your dog has B or T cell lymphoma.  

Staging refers to how far cancer has grown and spread in the body. Staging is important to provide prognostic information on which to base decisions and identify unrelated problems that could affect treatment choices. Dogs are usually staged with blood and urine tests, chest x-rays and abdominal ultrasound. 

The results of these tests will allow veterinarians to develop individualised treatment recommendations for your dog.

What are the treatment options available for dogs with lymphoma?

There are many levels of treatment options available for dogs with lymphoma.

If your dog has high-grade or large-cell lymphoma (which is the most common form of lymphoma in dogs), the prognosis for untreated dogs is guarded, with an average survival time of one to two months. Combination chemotherapy with a 4-drug combination, alongside with prednisolone is the standard of care treatment modality. It is usually administered over four to six months. With this treatment, most dogs can achieve complete remission (i.e. the disappearance of all signs of cancer) and live on average of about one year. However, this will depend on the presentation of each individual case. Moreover, occasionally dogs can potentially be cured, living up to 2 years or longer. Dogs with T cell lymphoma respond better to the addition of certain chemotherapy drugs. Therefore, The Pet Oncologist will recommend a different combination chemotherapy protocol than for dogs with B cell lymphoma. Other less costly options are available (including single-agent chemotherapy) and prednisolone alone.

If your dog has low-grade, small-cell or indolent lymphoma (which is uncommon), the gold standard treatment is different. It usually involves administration of oral chlorambucil chemotherapy and prednisolone indefinitely, which owners can administer from home. Although a cure is unlikely with this form of lymphoma, with treatment, dogs can live on average between one to three years.

The word ‘chemotherapy’ sounds scary, and I do not think I want to go down this path. What now?

That is a common initial response from pet owners when they hear the word 'chemotherapy'. However, chemotherapy in pets is much different to people. It is essential to understand the difference between chemotherapy treatment in human and veterinary medicine. In human medicine, the main objective of chemotherapy is to eliminate all cancer cells to try to obtain a cure. Usually, it is administered aggressively and has more chances of developing side effects. Curing cancer in veterinary medicine is desirable (and feasible for some cancers). However, due to the less aggressive approach (for example, lower dosages), pets usually tolerate chemotherapy far better than humans. The primary goals of chemotherapy are to minimise discomfort associated with cancer growth or slow the progression of cancer while striving to maintain or improve the pet's quality of life.

Pets experience fewer and less severe side effects than humans. Approximately 80% to 90% of dogs that receive chemotherapy experience no side effects. About 10% to 20% of dogs experience a chemotherapy side effect (such as lower energy levels, nausea, loss of appetite, vomiting or diarrhoea), which can often be managed with supportive home medications. Approximately 5% of pets experience a chemotherapy side effect that requires hospitalisation. For example, when the neutrophil count drop to a critically low value and dogs experience sepsis or infection. Less than 1% of chemotherapy side effects unexpectedly results in death. Occasionally dogs will require dose reductions or treatment breaks in order to tolerate chemotherapy.

If you decide to proceed with chemotherapy in your dog, any side effect he or she experiences is unacceptable. Please notify your veterinarian to make changes in future treatments to try to avoid these side effects from recurring and impacting your dog’s quality of life.

What if I have financial limitations?

If you have limited funds, it is still important to discuss all the available treatment options and associated costs with your veterinarian or a pet cancer specialist. At The Pet Oncologist, I work directly with your veterinarian to provide individualised treatment recommendations for each pet. I will review all the medical information submitted via the online submission form, and provide your veterinarian with a comprehensive written report within 1 to 3 business days. I will provide an interpretation of results, specific details about the cancer's biologic behaviour, prognosis, and multiple treatment options to cater to the individual needs of each pet and pet owner. I will also comment on whether further testing is required and address any specific questions or concerns. I can also provide chemotherapy protocols and client handouts to pet owners about the specific cancer and chemotherapy medications, to help pet owners make an informed decision. Unfortunately, due to legal reasons, I cannot provide online pet cancer advice directly to pet owners. However, your veterinarian will be able to discuss all these options with you before you consider treatment and can contact The Pet Oncologist with any questions or concerns. 

Can I start prednisolone while I consider my options?

Prednisolone is a steroid anti-inflammatory medication that can be used alone or with chemotherapy to treat lymphoma. It can make a sick dog with lymphoma feel much better within one to two days of administration. Occasionally dogs will go into complete remission with prednisolone alone. However, remission duration is often short-lived and lasts on average of around one to two months. Also, starting prednisolone (usually for more than one week) before chemotherapy may lead to multiple chemotherapy drug resistance, making chemotherapy less likely to work if owners change their mind and wish to pursue chemotherapy later. Although prednisolone is usually not recommended before starting chemotherapy, if all diagnostic tests are complete and results are pending, or chemotherapy drugs are not yet available, it may be necessary to start prednisolone before or in dogs that are clinically unwell (i.e. substage b) and aim to begin chemotherapy within one week.

What if I change my mind about starting chemotherapy and my dog has been on prednisolone for more than one week?

Your dog can still receive treatment, and it may still be effective.

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