Lymphoma is one of the most common types of cancer in dogs, and affects the cells of the immune system. Canine lymphoma can take many different forms. The most common is generalized lymphoma, which causes swelling of the lymph nodes that can be felt and seen through the skin. Less common forms include cutaneous lymphoma, which creates oozing skin sores, and several forms of “internal” lymphoma which can cause difficulty breathing, vomiting, or diarrhea.
High grade generalized lymphoma occurs in about 80% of cases, but there is also a less aggressive, “indolent” form of lymphoma that has a much longer survival rate… even without chemotherapy. This form is characterized by waxing and waning lymph node enlargement, typically of the head and neck.
While lymphoma can affect any type of dog, large breeds such as Boxers, Retrievers, and Shepherds are most commonly affected.
ARE ALL TYPES OF LYMPHOMA CREATED EQUAL?
There are two basic types of lymphoma, B cell and T cell. About 2/3 of lymphoma cases are of the B cell type, which carries a better prognosis than does T cell lymphoma. The only way to distinguish between B and T cell types is with specialized testing called flow cytometry or immunohistochemistry (IHC).
TREATMENT STRATEGIES FOR LYMPHOMA
There are four current approaches to the treatment of lymphoma:
1) TRADITIONAL CHEMOTHERAPY, where a rotation of four drugs is used to kill any rapidly-dividing cell in the body. Because it is the old standby, it is the most used and studied.
The ‘gold standard’ traditional chemotherapy for dogs with generalized lymphoma consists of a multi-agent protocol incorporating several injectable and oral drugs (L-asparaginase, vincristine, Cytoxan, prednisone, and doxorubicin), given on a more-or-less weekly basis for a period of several months. Each drug works to kill the lymphoma cells in a different way, and the drugs are alternated to prevent or delay the onset of lymphoma cell resistance and reduce the incidence of side effects. This protocol is called the CHOP protocol (an acronym of the ingredients) or the modified Wisconsin protocol, since it was developed at the University of Wisconsin. These protocols can be modified, and single-agent protocols can be used in cases of patients with specific medical conditions or where there are practical or financial limitations.
One downside to the use of such a protocol is the usual need for 12-16 visits to a veterinary cancer specialist, either in Santa Barbara or the Bay area. The other, as mentioned above, is the incidence of side effects due to the broad spectrum of cell kill. The most common side effects are vomiting, diarrhea, lethargy, and bone marrow suppression.
Recheck examinations and blood work are performed regularly during treatment to ensure that dogs are tolerating and responding to their protocol well, and that it is safe to proceed with subsequent treatments.
Most dogs with generalized lymphoma that are treated with a multi-drug (CHOP) protocol typically respond well, with 80-90% of them achieving clinical remission. A remission is NOT a cure, but rather represents the temporary disappearance of clinically detectable cancer. Relatively few dogs are truly cured of their lymphoma with treatment. The majority relapse at some point, at which time they may be treated with a different chemotherapy protocol. In general, the duration of these second and other subsequent remissions tend to be shorter than the first remission.
Each patient is an individual, and survival times vary depending upon a multitude of factors, including the presence of certain prognostic factors at diagnosis (including the specific type of lymphoma (B or T cell) and how a patient is feeling at diagnosis), as well as a patient’s response to therapy. The average survival for canine lymphoma patients with multicentric disease who are treated with chemotherapy is approximately one year.
A recent study (Brodsky, et al) evaluated the combination chemotherapy consisting of L-asparagine, mechlorethamine, vincristine, procarbazine, and prednisone (= L-MOPP) in dogs with T cell lymphoma. This protocol was associated with a complete remission rate of 78%, and overall survival of 270 days post-diagnosis. Interestingly, a subgroup of about 20% were still alive >900 days, which is much longer than commonly observed. This protocol is costly, has a high percentage of side effects, and can only be administered by an oncologist.
2) METRONOMIC THERAPY is a new approach that relies on small doses of one to two chemotherapy drugs given orally by owners at home. The incidence of side effects is generally very low because of the smaller doses used more frequently. This approach has been studied extensively in other forms of cancer, and is actively being researched for lymphoma.
Dogs and cats with resistant lymphoma or with families who cannot afford the routine chemotherapy protocols may receive metronomic chemotherapy, although the benefits are anecdotal and published data for benefit is lacking. It is important to know that using metronomic therapy for lymphoma patients is not intended to induce remissions. It is best to use metronomic therapy following induction protocols (like CHOP, above) when the patient is in clinical remission. Using continuous low dose cytoxan, chlorambucil, melphalan, procarbazine, and/or dexamethasone may be helpful in sustaining longer remissions or partial remissions.
3) NEW THERAPIES FOR LYMPHOMA include targeting JUST the cancer cells (Tanovea, below) or priming the patient’s own immune system to fight the cancer (monoclonal antibodies and Autologous Cancer Vaccine, below)
A) AUTOLOGOUS CANCER VACCINES: A new approach to fighting cancer with solid tumors (like the enlarged lymph nodes of lymphoma patients) is to surgically remove tumor tissue and use it to actually formulate a vaccine against the tumor cells. This is the most natural way to fight cancer, as the resultant vaccine is very specific for the patient’s tumor type. The lead researcher is a very well respected cancer immunologist on the human side, who chose to devote his effort to our dogs after his own dog developed cancer. We can help you with this!!
B) TANOVEA is a new drug in the veterinary field. Unlike traditional chemotherapy, which targets and attacks ANY dividing cells in the body—hence the side effects of hair loss, nausea, etc—Tanovea preferentially targets and attacks only the cells causing lymphoma. It is effective in 60-80% of cases of lymphoma, and works best with B cell types which have not previously undergone chemotherapy. It is given intravenously, every three weeks..
4) INTEGRATIVE THERAPY
Listen, there are no good studies supporting the use of integrative therapy to help dogs fight lymphoma. Never have been, never well be… because the funding just isn’t there. However, that does not mean that such therapy has no benefit for our dogs in their journey through cancer.
Our bias toward integrative therapy for canine lymphoma includes these facts:
- a) barring the occasional miracle, there is no medical cure for lymphoma
- b) there is VERY solid evidence supporting the use of integrative therapy in humans (see below)
- c) and if we can benefit our dogs in their fight against cancer… in any way… without side effects,
then we should.
There are two good resources that will enable you to do your own research on natural therapies:
There are five forms of integrative therapy that have been proven beneficial for humans with Non-Hodgkins Lymphoma, which is the analog for canine lymphoma. Do your own research, starting with the studies below.
If you believe in doing everything you can for your pet with lymphoma, we can help you!!
2) DECAFFEINATED GREEN TEA (which contains the active ingredient EGCG)
4) FISH OIL
5) REISHI MUSHROOMS