Bill is a 13 year old, male neutered Golden Retriever. His owner had noticed a new mass on his chest and brought it to the doctor’s attention. This mass was actually a lymph node. The doctor recommended that we perform an FNA and cytology. An FNA is a fine needle aspirate. This involves inserting a needle into the mass and aspirating cells out of it. These cells are then put onto a slide and analyzed by a pathologist at the lab. Our doctors feel that about 70% of soft tissue aspirates give a diagnosis. This is because only a very small sample of cells is being evaluated. A biopsy, or removal of the entire mass, generally will give a definitive diagnosis.
In Bill’s case his cytology confirmed lymphoma. Lymphoma (or lymphosarcoma) is the most common tumor of white blood cells affecting dogs and cats. It primarily affects lymph nodes or visceral organs such as the liver or spleen.
Chemotherapy drugs are most active against rapidly-dividing cells. Most tumor cells are rapidly-dividing, while most normal cells are not. Normal cells that are rapidly-dividing are mostly in the gastrointestinal (GI) tract, which is why GI signs are the most common side-effect of many chemotherapeutic drugs. Chemo also has a large effect on bone marrow (termed myelosuppressive). Bone marrow is a flexible tissue that is found in the interior of bone. It produces new blood cells, such as platelets, red blood cell and most white blood cells. A CBC (complete cell count) should be run 1 week after administration of chemotherapy to ensure that white blood cells are not too low. Depending on the level of white blood cells, the chemo can be reduced, or postponed completely until the levels are within a safe range.
Bill’s chemotherapy protocol involves 16 treatments over 6 months. The first 8 doses are given weekly (with a break between the 4th and 5th doses) and then treatments are given every other week for 8 additional treatments. This protocol will put >85% of patients in to a complete remission and on average the patients will have a good quality of life for 1 year with 25% of dogs living 2 years or longer (longer and shorter times, though, are possible). Patients living longer than a year may need additional chemotherapy.
Bill’s specific chemotherapy drugs included Vincristine, Asparaginase (Elspar), Cyclophosphamide (Cytoxan) and Adriamycin (Doxorubicin).
Vincristine is a drug derived from a flowering plant called periwinkle. It is frequently use in combination with other drugs. Possible side effects include muscle weakness, constipation, hair loss and jaw pain.
Elspar is an enzyme derived primarily from the bacterial E.coli and is used commonly in cancer treatment of some animal and human cancers. Possible side effects include vomiting and/or diarrhea, hives on the skin or restlessness and difficulty breathing (rare). Because a hypersensitivity reaction is the most common when using Elspar, we premedicated Bill with Benadryl prior to administration to help prevent a reaction.
Cytoxan is a frequently used drug in cancer chemotherapy. It is particularly irritating to the bladder, and can often cause bloody urine. Other side effects also include low white blood cell counts, loss of appetite and nausea/vomiting (rare). Because of its effects on the bladder, we gave Bill an injection of Furosemide (Lasix) as a diuretic to help increase urination and flush his bladder.
Adriamycin is the hardest of these chemotherapy drugs on the body. It is considered cardiotoxic (toxic to the heart), and an echocardiogram is recommended prior to administration. An echocardiogram is an ultrasound of the heart. The day he received Adriamycin, we checked an ECG (rhythm strip of the heart) prior to giving the Adriamycin to ensure that there were no abnormalities prior to giving the medication. It was normal. We also gave Bill an injection of Benadryl to help decrease the chance of reaction.
In addition to these drugs, Bill was also receiving Prednisone as an oral steroid at home throughout his treatments. It acts as an immunosuppressive drug to help slow the progression of cancer cell multiplication. In addition it also increases appetite and thirst.
Bill received his first dose of chemotherapy on December 16th, 2010. He received an injection Benadryl, and then had an IV catheter placed. He received Vincristine IV and Elspar IV, and then was maintained on IV fluids for several hours afterwards. Bill’s owner reported that he was ‘super dog’ two days later! He tolerated the drugs fine and felt great.
His second dose was administered on December 23rd. We ran a CBC prior to the chemotherapy and his white blood cells were normal, but his red blood cells low (also known as anemia). Dr. Miele did not feel that this contraindicated receiving his chemo this week, but if it continued to drop, we may want to postpone his treatments. He received Cytoxan IV and Lasix also IV. He was similarly kept on IV fluids for a few hours after the treatment. The following day Bill returned to the hospital because he was vomiting and lethargic. Dr. Nieh felt as though it could have been a reaction to the Cytoxan. Other causes could be that he ate something that he didn’t agree with and it was not related to the chemotherapy at all, another disease process, or even the lymphoma spreading. Bill was sent home with oral medications; an appetite stimulant (Mirtazapine), a stomach protectant (Sucralfate), a gastrointestinal antibiotic (Metronidazole) and an acid reducer (Pepcid). We rechecked a CBC on December 28 and his white blood cells were normal and his anemia was stable. He was OK to receive his next dose of chemotherapy on schedule.
Bill received his third dose on December 30th. He received Vincristine again alone. Again he was maintained IV fluids for a few hours afterwards. Because of his stomach upset after the second dose of chemotherapy, we sent Bill home with medications to have on hand in the event that he had a similar reaction. He was sent home with Metronidazole for potential diarrhea and Cerenia for vomiting. When we called the following day to check in, he was doing great. No vomiting or diarrhea was seen, and he seemed to be acting normally.
Bill’s fourth dose of chemotherapy was administered on January 7th. Prior to treatment we checked a CBC and . We checked an ECG as well, and he had a normal rhythm. We gave an injection of Benadryl and then gave the Adriamycin IV slowly over 1 hour. We listened to his heart and lungs closely every few minutes during this administration to ensure that there was no change in his heart rate or rhythm. He received IV fluids for a few hours after the treatment. The following day Bill was lethargic, his appetite was down and he had intermittent tremors/trembling. We had decreased Bill’s dose of Prednisone after the Adriamycin, so Dr. Nieh recommended that we increase it back to the previous dose. She also recommended he receive Cerenia for vomiting/nausea, Pepcid as an acid reducer, and Mirtazapine as an appetite stimulant. If his thirst and appetite did not improve, we may need to admit him to the hospital for IV fluids. Bill seemed to have waxing and waning symptoms at home from the 7th until the 11th. He did seem to slowly improve over time.
Bill’s fifth chemotherapy treatment was administered on January 20th. We checked a CBC prior to giving the chemo and his white blood cells were normal and anemia stable. On examination, Dr. Miele was concerned that Bill’s abdomen was large. He was worried that his abdomen was fluid-filled. His abdomen could have also been bloated secondary to the Prednisone use, or because his organs were enlarged. Fluid can build in the abdomen for several reasons when a pet has cancer;
- The lymphatic system can become backed up or obstructed due to the cancer, and the abdomen can fill with lymph fluid.
- The cancer could have spread to the gastrointestinal tract, and perforated the intestines, causing bacteria to infiltrate the abdomen, causing sepsis.
- The cancer could have spread to the heart, causing heart failure, and heart failure can cause fluid build-up in the abdomen as well.
Dr. Miele recommended that we take abdominal x-rays to evaluate what could be the cause of the bloated abdomen. There was no fluid seen in his abdomen, but his liver was very large. This could be due to the Prednisone use (because it can effect the liver), or also due to spread of the lymphoma. We continued as planned with his treatment. He received Vincristine IV and fluids afterwards. The following day we called to check in, and Bill seemed to be doing well. He was eating a new food, Hills n/d (the ‘n’ stands for neoplasia, meaning cancer). This food is specially formulated for patients with cancer. Overall he seemed to be doing well.
Bill is currently doing well. We are not anticipating that this will be a cure of his cancer, but that it may give him more quality time at home with his family.