Client Information on Canine Lymphoma

Please understand the following information is offered as a courtesy and is not intended to provide a diagnosis or medical recommendation for your pet.

Lymphoma is a tumor of lymphocytes. Lymphocytes are cells of the immune system that are located within lymph nodes, bone marrow, liver, spleen, and other organs. Because lymphocytes normally are throughout the body, lymphoma is also considered to be throughout the body, even if we only identify it in one location. Also because lymphoma is considered throughout the body, we must treat the entire body with medication. Surgery and radiation are generally not advised as the only treatments because they can only treat part of the body and the lymphoma will return sooner than if medications are also used.

This disease is generally quite responsive to therapy. As a general rule, lymphoma is similar to non‑Hodgkin's lymphoma in humans. As in humans, lymphoma in dogs is generally not painful. Most dogs are not aware that they have enlarged lymph nodes. Most owners are pleased with their pet's quality of life while receiving therapy. Without therapy, the average dog with lymphoma only does well for approximately 30 days after the original diagnosis. Lymphoma is, however, usually quite responsive to chemotherapy and we are generally able to establish remission of the cancer.

Remission is not the same as a cure. Remission is attained when all evidence of the lymphoma has disappeared to a point where your dog's clinician, your dog and you will not be able to detect any evidence of tumor. For our pets, we have not been able to convert our success in providing remissions into achieving life-saving cures. Please understand that because of our inability to cure lymphoma, the quality of your pet’s life is even more precious.

Treatment Options For Lymphoma

When considering options, think about cost, time required to have your pet treated, the potential for adverse effects, and the opportunities to improve quality of life and length of life. The cheaper, less time-intensive protocols are usually less toxic and less effective (e.g. prednisone). More effective protocols are more time intensive with more chance for effectiveness (e.g. Wisconsin protocol).\Some treatment options (Lomustine or Adriamycin) are mid‑range in potential time, cost, efficacy, and possibility of toxicity.

Prednisone Protocol:

Prednisone is inexpensive and mild to moderately effective for the treatment of lymphoma. Its effect is short, increasing survival time only by 30 days. The single largest concern with prednisone treatment is that it can cause “multi-drug resistance” when used alone, such that, if in the future you decide you would like to try other medications, those medications are not going to be as effective.

Prednisone and Lomustine (CCNU) Protocol:

We can generally extend the effectiveness of prednisone by combining it with another medication. By combining prednisone with either Lomustine, we may be able to extend the remission time over the effect of prednisone alone. Because the studies have not yet been performed we do not truly know, but hope that we could extend survival to between 4-6 months. These medications are given by mouth every 3 weeks and require a complete blood count before each treatment and 1 week after treatment.

Adriamycin L‑Asparaginase Protocol:

Adriamycin chemotherapy is one of the most effective treatments for lymphoma. Adriamycin therapy is combined with one dosage of L-asparaginase. L‑asparaginase is an enzyme that lowers the level of asparagines that is needed by tumor cells. When used appropriately, the drug is unlikely to cause significant adverse effects.

In a recent study completed at Colorado State University, two‑thirds of the owners and the attending veterinarians advised us that the dogs treated with Adriamycin did not have any significant adverse effects other than being lethargic a day or two after treatment. Of the one third that did have adverse effects, the majority of these effects were mild and self‑limiting. They include, but are not necessarily limited to, loose stool, upset stomach, low white blood cell count and a fever, as well as lethargy and loss of appetite. If treated appropriately by your veterinarian or by our hospital, these adverse effects can be prevented in subsequent treatments with specific therapy. Approximately 5% of dogs that receive Adriamycin chemotherapy can have serious potentially life-threatening adverse effects. These serious adverse effects can result in hospitalization and the need for specific therapy.

Approximately 75% to 85% of dogs with lymphoma will respond to Adriamycin therapy. They will attain a complete remission (reduction of all tumor to a point where it is not observable by you or the attending clinician). The average duration of remission for dogs that are treated with Adriamycin that attain a complete remission is approximately 6-7 months. This treatment is given every 3 weeks with a complete blood count (CBC) before each treatment and one week after treatment. When dogs come out of remission, they can be retreated with other chemotherapeutic agents.

COAP Protocol:

This protocol is a combination of medications given by mouth at home and injections of vincristine in the hospital. The first portion of this protocol is a series of 8 visits once a week visits to the hospital for a complete blood count and an injection. Following these first 8 weeks, your pet begins a maintenance protocol which only requires a hospital visit once every 4 weeks while you continue medications at home. These weekly visits continue until the lymphoma returns and then other medications are used. The average first remission with this protocol is 8-10 months. Generally, we expect few side effects, but the most common are low white blood cell counts (which is why we monitor the complete blood counts) and gastrointestinal upset (which is generally mild).

Wisconsin protocol:

The Wisconsin protocol is an example of a combination chemotherapy protocol that incorporates the use of five drugs. Remission rates are a little higher than Adriamycin (doxorubicin) and the average duration of first remission is longer at 9-11 months. This protocol requires the most time and is the most costly but does have the highest chance for efficacy and, unfortunately, side effects (though we still expect them to be mild). The protocol involves weekly visits for nine weeks, and then every other week until week twenty-five when all chemotherapy stops until your pet comes out remission. When your dog comes out of remission, we will restart the Wisconsin protocol or may choose a different combination of medications.

General comments:

As a general rule, the duration of the first remission is the longest. The probability of attaining a subsequent remission is a little more difficult than attaining the previous remission. In addition, the duration of the subsequent remission is approximately one‑half of the duration of the previous remission. That is, if your dog was treated with chemotherapy protocol and was in remission for nine months, it is a little more difficult to induce a second remission with another protocol and the duration of that second remission is likely to be approximately one‑half of the duration of the previous one (4.5months). A third remission can be attained with other drugs. However, the probability of attaining a third remission is more difficult than attaining the second remission. In addition, if your dog was in remission for 4.5 months during the second remission, it is reasonable to presume that your dog will be in remission for 2.25 months on the third remission. A variety of other drugs can be utilized to attempt to induce subsequent remissions.

Please know that we are here to assist you in whichever treatment plan you select. Also, please know that if your pet does not feel well during treatment or you have a change of heart for whatever reason, we can change or stop the treatment. Our commitment is to you and your pet’s quality of life.