Today's Veterinary Nurse

SEP-OCT 2017

Practical, peer reviewed, state-of-the-art companion animal nursing and technical educational articles with CE. Promotes better health for animals and career growth and development for veterinary technicians and veterinary assistants.

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CONTINUING EDUCATION TODAY'S VETERINARY TECHNICIAN | September/October 2017 | 51 challenge—administration of chemotherapy may cause the white cell count to drop further, leaving the patient susceptible to infection. Conversely, the patient may have leukocytosis secondary to circulating cancer cells (leukemia) or a stress leukogram. Æ Thrombocytopenia may be secondary to bone marrow involvement or immune mediated. Æ Hypercalcemia of malignancy is a paraneoplastic syndrome that is commonly associated with T-cell lymphoma. It is due to the tumor producing parathyroid hormone–related protein, which mimics parathyroid hormone in the body, although the reason for the protein production is unknown. Hypercalcemia is a medical emergency because, if persistent, it can lead to renal failure (BOX 2) . Confirmation of hypercalcemia of malignancy requires a specific panel of tests. Æ Azotemia may be present because of many factors, including dehydration, persistent hypercalcemia leading to calcification of the renal cortex, or renal involvement of the lymphoma. Æ Elevated liver enzymes may be present if the liver is involved. Depending on severity, liver involvement may warrant alteration of the chemotherapy protocol because many of the drugs used are metabolized by the liver. Impaired clearance of chemotherapeutics can lead to increased side effects or a relative overdose. Treating the lymphoma with drugs that do not require hepatic clearance may allow the enzyme levels to normalize, and then the protocol may be adjusted. Substage Lymphoma is further classified by substage, either a or b, which simply refers to how the patient is doing clinically. A patient that presents with a normal appetite and energy level would be classified as substage a, whereas a patient that is feeling poorly on presentation would be substage b. Patients that do not feel well on presentation have an overall poorer response rate and prognosis. It is better to initiate therapy while the patient is feeling well than to wait until the patient is compromised. Immunophenotype Another diagnostic tool that adds prognostic information is phenotyping. This can be determined via several tests, including flow cytometry, clonality, immunohistochemistry, and immunocytochemistry. B-cell lymphoma is associated with longer survival and better quality of life. 1,2 CHEMOTHERAPY Treatment Goals The goal of lymphoma treatment is to induce clinical remission, indicated by lack of measurable disease, while retaining a high quality of life. Because lymphoma is a systemic disease, chemotherapy is the foundation of treatment. Using calculated lower doses that are used by human oncologists usually keeps side effects minimal and short term; however, some patients may require hospitalization, and death from tumor lysis syndrome can occur. A common client misconception is that administering chemotherapy to animals is in some way inhumane. This stems from assumptions about the goals of cancer therapy in companion animals and the incidence of side effects from therapy. It can be helpful to the client to present cancer therapy as treatment of a chronic condition, similar to treatment of renal or heart disease. Many clients are willing and able to administer daily medication or SC fluids, and a weekly chemotherapy visit is much less daunting when framed in those terms. Treatment Options Many options are available for lymphoma treatment, varying in cost and survival time. As stated before, median survival time for untreated high-grade lymphoma is 6 to 8 weeks. Treating with prednisone can improve quality of life and result in 2 to 3 months of survival time. Treatment with a combination chemotherapy protocol that includes doxorubicin results in an average first remission time of 8 to 10 months and a median survival of 1 year. Adding in half-body radiation therapy appears to increase overall survival times for canine lymphoma patients. 1,3 Peer Reviewed The most important and effective way to lower calcium levels in lymphoma patients is to treat the underlying cause (ie, the lymphoma). Initiation of l -asparaginase and steroid therapy to reduce the population of cancer cells leads to the reduction of calcium levels. Often, however, lymphoma patients present with dehydration and require aggressive fluid therapy. After adequate hydration is achieved, a diuretic, such as furosemide, may be considered. Corticosteroids should not be administered before confirmation of the lymphoma diagnosis because rapid reduction of the tumor burden can make definitive diagnosis difficult or impossible. A bisphosphonate (pamidronate, zoledronate) may be administered to lower the calcium levels; however, treating the lymphoma is still the goal, and care must be taken to protect the kidneys during administration. BOX 2 Treating Hypercalcemia in Lymphoma Patients

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